Collagen Peptides Unflavored by Ancient Nutrition

EFFECTIVE

• Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
• Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
• Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
• Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

• Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
• Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
• Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
• Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

POSSIBLY EFFECTIVE

• Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
• Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
• Hypertension. Oral calcium seems to reduce blood pressure by a small amount. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies show that intake of calcium supplements or dietary calcium modestly reduces blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as salt-sensitive people and patients with low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221). Also, a meta-analysis of clinical research shows that calcium intake during pregnancy reduces systolic blood pressure in offspring by 1-2 mmHg (38852). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplement sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367).
• Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
• Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia in high risk pregnancies, especially if calcium intakes are low. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces pregnancy-related hypertension and pre-eclampsia (973,1833,8828,39043,39319,39426,96480). Calcium appears to reduce the risk of pre-eclampsia by about 50% when compared with placebo. One meta-analysis of 19 controlled trials involving over 29,000 pregnancies found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (96480). Calcium appears to have the greatest effect in individuals at high-risk of pre-eclampsia or with low calcium levels, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,96480,99714). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely. Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium supplementation 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low, in order to prevent pre-eclampsia (97347).
• Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
• Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

POSSIBLY INEFFECTIVE

• Breast cancer. Oral calcium does not seem to be beneficial for breast cancer prevention. Details: Although some population research disagrees (15631,39041,95811,107237), most research shows that increased calcium intake is not associated with a reduced risk of breast cancer (15631,16715,98895,107236,107237). Subgroup analyses of population research suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237). Another subgroup analysis in a large meta-analysis of population research also suggests that dietary intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most other research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
• Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: The most recent and robust meta-analysis of clinical research shows that calcium supplementation with or without vitamin D is NOT associated with reduced fractures in older adults without osteoporosis (95822). A large-scale study in postmenopausal females aged 50-79 years suggests calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the Women's Health Initiative study found that, in older females with the lowest genetic susceptibility to low bone mineral density (BMD), taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
• Obesity. Oral calcium does not seem to improve weight loss. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). The most recent meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
• Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308).

INEFFECTIVE

• Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
• Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
• Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
• Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
• Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
• Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
• Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
• Diabetes. It is unclear if oral calcium is beneficial for type 2 diabetes prevention. Details: Some population research has found that a higher intake of calcium from diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473). However, population research is often limited by confounding variables. For example, one analysis found that any beneficial effect might be influenced by concomitant magnesium intake (96473). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis. This study is limited because it was not determined whether increased serum calcium was due to increased calcium intake or another factor such as parathyroid function (95815).
• Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
• Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
• Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
• Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
• Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
• Hypercholesterolemia. It is unclear if oral calcium is beneficial for hypercholesterolemia. Details: Some evidence shows that taking calcium carbonate 400 mg three times daily reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% after 6 weeks of treatment when used in combination with a low-fat diet (American Heart Association Step 1) (2557). In contrast, a study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years might INCREASE total cholesterol levels by about 12 mg/dL when compared with placebo. This same study showed an association between calcium supplementation and an increase in total cholesterol levels and carotid intimal thickness in postmenopausal females, but not premenopausal females (97350). A recent meta-analysis of randomized controlled trials which included both healthy patients and patients with dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is more effective in patients with dyslipidemia at baseline. It is unclear if this effect is due to calcium, vitamin D, or the combination (107227). However, other research shows that taking a specific supplement containing calcium 600 mg plus vitamin D 200 IU (Caltrate 600 D, Wyeth Consumer Healthcare Inc.) twice daily in combination with calorie restriction does not reduce total or LDL cholesterol levels when compared with placebo (15601).
• Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
• Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
• Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
• Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
• Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
• Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
• Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
• Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
• Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
• Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
• Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
• Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

(Read more about CALCIUM)

POSSIBLY EFFECTIVE

• Aging skin. Oral collagen peptides seem to improve skin hydration and elasticity in older adults. However, it is unclear if any improvements related to wrinkles are cosmetically important. Details: Meta-analyses of the available research, as well as multiple individual clinical studies, show that collagen peptide products, taken in doses of 372 mg to 12 grams daily for 4-12 weeks, improve skin hydration and elasticity in older adults. Studied products include Peptan-F or Peptan-P (Rousselot), Wellnex (Nitta Gelatin), Gold Collagen Active (Minerva Research Labs), VERISOL (Gelita AG), and Nippi peptide FCP-EX (Nippi/Shizuoka) (97632,100703,101597,104647,107460,112457). Pooled study results also suggest that hydrolyzed collagen sourced from fish improves skin hydration and elasticity, while collagen peptides originating from chickens seems to modestly improve skin elasticity but not hydration. Collagen peptides derived from bovine do not seem to improve skin hydration or elasticity (112457). Despite research showing improvement in skin hydration and elasticity, it is unclear if collagen peptides reduce skin wrinkles to a cosmetically significant degree, as most studies have not evaluated this outcome. In one clinical study, taking a freshwater fish-derived collagen peptide (Vinh Wellness Collagen, Vinh Hoan Corporation) 10 grams every morning reduced wrinkle count in the nasolabial region of the right side, but not the left side, of the face by 24% when compared with placebo. Collagen peptides did not improve participant-reported measures of wrinkles, elasticity, hydration, and others, when compared with placebo (104639). Another clinical study shows that taking a specific fish scale-derived collagen peptide (Wellnex, Nitta Gelatin) with either a high or low ratio of prolyl-hydroxyproline and hydroxylpropyl-glycine as 5 grams orally daily for 8 weeks modestly improves wrinkle depth and roughness, but not wrinkle volume, when compared with placebo. The product with a high ratio of dipeptides had a larger effect (97632). Also, one clinical study shows that taking a specific product containing porcine collagen type I peptides (VERISOL, Gelita AG) 2.5 grams daily for 8 weeks reduces eye wrinkle volume by 20% when compared with placebo (101648). Two similar moderate-size clinical studies in middle-aged adults with crow's feet wrinkles and dry skin show that taking specific low-molecular-weight fish-derived collagen peptide products (Geltech Co.; CPNS) at doses of 2000 mg or 1650 mg, respectively, daily for 12 weeks improves eye wrinkles, skin hydration, and elasticity when compared with placebo (110729,110730). While investigator satisfaction scores regarding wrinkle reduction were modestly improved, participant satisfaction was not improved (110729). Small clinical studies have shown contradictory findings when collagen peptides are taken in combination with other ingredients. In one clinical trial, a specific drink (Diva Luxe) providing fish collagen peptides 5.5 grams plus Chenopodium formosanum extract 1 gram daily for 8 weeks improved some measures of skin brightness and hydration, but not wrinkles and crow's feet, when compared with placebo (104646). Another small clinical study shows that taking collagen peptides 4 grams daily in combination with coenzyme Q10 50 mg, vitamin C, vitamin A, and biotin for 12 weeks reduces wrinkles and improves skin smoothness by a small amount when compared with placebo. However, there was no difference in skin elasticity or hydration (104638). A clinical study in older females shows that taking collagen peptides 9 grams in combination with zinc and vitamins A, C, and E daily for 90 days increases stratum corneum water content and skin viscoelasticity when compared with placebo. However, it is unclear if the improvement from baseline differed between groups. Small improvements in dermal echogenicity, wrinkles, or skin pores were noted in some facial regions, but the lack of statistical comparison to placebo limits the validity of these findings (107464). Some small clinical studies have shown mixed effects with low doses of collagen peptides from preliminary clinical research using BioCell Collagen (BioCell Technology, LLC) or Celergen (Laboratories-Dom) (28681,97930). It is unclear if any improvements from these studies are due to collagen peptides, other ingredients, or the combinations. Topical application of collagen peptides has been minimally evaluated. A very small observational study in older adults has found that application of a carbopol gel containing collagen peptides 1% to the periorbital area twice daily for 8 weeks is associated with increased skin hydration and elasticity and reduced transepidermal water loss, skin roughness, and wrinkles when compared with baseline (107459). The validity of these findings is limited by poor study methodology, lack of statistical comparison to baseline, and lack of a comparator group.
• Dry skin. Oral collagen peptides seem to improve skin hydration and elasticity in adults with dry skin. However, their effect on other measures of dry skin is unclear. Details: A meta-analysis of 19 clinical studies, along with several small and moderate-sized individual studies, some of which are included in the meta-analysis, show that taking collagen peptides 372 mg to 12 grams daily for 4-12 weeks improves skin hydration and elasticity when compared with placebo in healthy adults (107461,110729,110730,112457,112458). Some studies show that collagen peptides improve skin roughness (107461), decrease peeling (110729,110730), and increase stratum corneum and epidermis water content (107462) but not skin gloss (107461) or elasticity (107462). Some research shows that collagen peptides reduce transepidermal water loss (107462), while another study shows no change (107461). Subgroup analysis of the meta-analysis suggests that hydrolyzed collagen sourced from fish improves skin hydration and elasticity the most, while collagen peptides originating from chicken seem to modestly improve skin elasticity but not hydration. Collagen peptides from bovine do not seem to improve skin hydration or elasticity (112457). Studied products include FCP-Z (Nippi Co., Ltd), Geltech Co., CPNS, and GPVGPS Collagen (Daehan Chemtech) (107462,110729,110730,112458). Collagen peptides have also been evaluated in combination with other ingredients. A small clinical study in healthy adults with low skin moisture shows that drinking 30 mL of a beverage containing fish scale-derived collagen peptides 10 grams and ornithine 400 mg (FUJIFILM) daily for 8 weeks does not improve skin moisture but seems to improve skin elasticity and reduce water loss when compared with placebo (101607). Another very small clinical study in a mixed population of patients with dry skin and mild atopic dermatitis shows that twice daily application of an emollient containing collagen peptides, soluble proteoglycan, and hyaluronic acid for 4 weeks reduces itching severity from moderate at baseline to mild or almost none. Transepidermal water loss and skin hydration also improved when compared to baseline (107465). The validity of these findings is limited by the lack of a comparator group. Both of these studies are limited by their small size, and it is unclear if any improvements are due to collagen peptides, other ingredients, or the combination.

POSSIBLY INEFFECTIVE

• Muscle strength. Most research suggests that oral collagen peptides do not improve leg strength. However, they may improve hand-grip strength and fat-free mass. Details: Small clinical studies in healthy male and female athletes or non-athletes undergoing resistance or other training show that taking collagen peptides 15-30 grams daily or after training sessions for up to 15 weeks, with or without vitamin C, does not improve leg strength (i.e. squat strength, knee extension, or flexor strength) when compared with placebo (101608,104641,107457,110668,110669). Similarly, 2 very small clinical studies in healthy adults show that taking a specific oral collagen peptide product (Bodybalance, Gelita AG) 5-15 grams daily while completing a resistance training program for 14-15 weeks increases patellar tendon cross-sectional area but does not improve most measures of tendinous tissue remodeling including patellar tendon size, vastus lateralis aponeurosis size, patellar tendon mechanical properties, tendon stiffness, maximal knee extension strength, or rectus femoris muscle cross-sectional area when compared with placebo (112452,112454). However, a small clinical study with the same product in untrained females aged 18-50 years shows that taking 15 grams daily in addition to resistance training three times weekly for 12 weeks improves hand-grip strength when compared with resistance training and placebo (101608). In untrained males aged 30-60 years, taking the same dose of this collagen peptide product along with resistance training for 12 weeks improves fat-free mass by 3 kg, compared with 2 kg with resistance training and placebo. A post-hoc exploratory analysis suggests that the effects seen in males are similar to those seen with whey protein (107457).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there has been interest in using oral collagen peptides for acne, there is insufficient reliable information about the clinical effects of collagen peptides for this condition.
• Androgenic alopecia. Oral collagen peptides have only been evaluated in combination with other ingredients, their effect when used alone is unclear. Details: A moderate-sized clinical study in adults with androgenic alopecia or telogen effluvium shows that taking a combination product containing hydrolyzed collagen 300 mg, taurine, cysteine, methionine, iron, and selenium (GFM Oral, Cantabria Labs) daily along with conventional therapy, consisting primarily of finasteride or minoxidil, for 12 weeks improves hair loss when compared with conventional therapy alone (111636). It is unclear if this effect is due to collagen peptides, other ingredients, or the combination.
• Athletic performance. It is unclear if oral collagen peptides improve performance in most athletes. Details: In recreationally active female runners undergoing resistance and endurance training 3 times weekly, clinical research shows that taking collagen peptides 7.5 grams twice daily for 12 weeks increases running distance by approximately 1,034 meters, compared with an increase of 703 meters in those taking placebo, although there was no effect on speed (104641). A clinical study in healthy young male athletes undergoing heavy strength and power training shows that taking collagen peptides 20 grams and vitamin C 50 mg daily for 3 weeks improves squat performance and countermovement jump performance when compared with placebo. However, removal of a single outlier negated the statistical significance of most of these findings (107456). Also, it is unclear if any improvements from this study are due to collagen peptides, vitamin C, or the combination.
• Atopic dermatitis (eczema). It is unclear if oral or topical collagen peptides are beneficial for improving the severity of eczema. Details: A small clinical study in patients with atopic dermatitis shows that taking a porcine skin-derived collagen peptide with a high ratio of tripeptides with glycine-X-Y sequences, 3.9 grams daily for 12 weeks, improves symptoms and severity of eczema when compared to baseline. There was no improvement in the group taking the same dose of porcine skin-derived collagen peptide without the high ratio of tripeptides (101605). Another very small clinical study in a mixed population of patients with atopic dermatitis and dry skin shows that twice daily application of an emollient containing collagen peptides, soluble proteoglycan, and hyaluronic acid for 4 weeks reduces itching severity from moderate at baseline to mild or almost none. Transepidermal water loss and skin hydration also improved when compared to baseline (107465). It is unclear if any improvements are due to collagen peptides, the other ingredients, or the combination. Both of these studies are limited by their small size and lack of comparator groups.
• Burns. Some preliminary clinical research suggests that oral collagen peptides might reduce the time needed for burn healing. Details: In male patients with 20% to 30% body surface area burns, a small clinical trial shows that taking a collagen-based supplement providing collagen peptides (Amutiya, Qom) 36 grams daily for 4 weeks improves wound healing when compared with taking an isocaloric supplement containing the same amount of soy protein. Complete wound healing occurred in 50% and 100% of patients taking collagen for 2 and 4 weeks, respectively, compared with 7% and 40% of those taking the isocaloric product. The duration of hospital stay was not significantly different between the two groups (104642). A small clinical study in hospitalized adults with 20-45% body surface area 2nd or 3rd degree burns shows that consuming a beverage containing collagen peptides 40 grams daily for 4 weeks shortens the time to wound healing, improves scar scores, and reduces the duration of hospital stays but does not limit wound infections when compared with placebo. Adding fish oil 3 grams daily did not further improve outcomes (110667).
• Brittle nails. One small clinical study suggests that oral collagen peptides may improve nail health in people with brittle nails. Details: A small clinical study shows that taking a specific porcine type I collagen peptide product (VERISOL, Gelita AG) 2.5 grams daily for 6 months improves overall symptoms of brittle nail syndrome, increases nail growth rate by 12%, and reduces broken nail frequency by 42% when compared with baseline (101606). This study was limited by its small size and lack of a comparator group.
• Cellulite. One small clinical study suggests that oral collagen peptides may reduce cellulite. Details: In people with cellulite, a small clinical study shows that taking specific collagen peptides (VERISOL by Gelita AG) 2.5 grams daily for 6 months seems to reduce cellulite, skin waviness, and dermal density by a small amount when compared with placebo (101619).
• Cognitive function. It is unclear if oral collagen peptides are beneficial for improving memory. Details: In healthy adults, preliminary clinical research shows that taking collagen peptides 5 grams daily for 4 weeks improves some measures of memory and verbal learning when compared to baseline (104643). This study was limited by its small size and lack of a comparator group.
• Dermatoporosis. One small clinical study suggests that using oral or topical collagen peptides does not improve this condition. Details: A small clinical study in post-menopausal patients aged 70 years on average with mild dermatoporosis shows that taking collagen peptides 5 grams daily, applying a collagen peptides 2.5% serum 3 pumps nightly to each forearm, or using these in combination for 6 months does not improve skin lesions, epidermal thickness, collagen or elastin density, or patient perception of skin improvement when compared with placebo (110731). However, it is unclear if these results apply to patients with more severe dermatoporosis.
• Diabetes. Some preliminary clinical research suggests that oral collagen peptides might have a small effect on glycemic indices. Details: Preliminary clinical research in patients with type 2 diabetes shows that taking fish-derived collagen peptides 6.5 grams orally twice daily for 3 months, in addition to treatment with antidiabetes drugs, may modestly reduce levels of fasting blood glucose, glycated hemoglobin, and fasting blood insulin and may increase levels of insulin sensitivity when compared with antidiabetes drugs and placebo (101626,101627).
• Erythema. It is unclear if oral collagen peptides are beneficial for erythema. Details: A moderate-sized clinical study in adults with dry and wrinkled eye skin shows that taking low-molecular weight collagen peptides (GPVGPS Collagen, Daehan Chemtech) 2000 mg daily for 12 weeks reduces erythema index when compared with placebo (112458).
• Exercise-induced gastrointestinal (GI) symptoms. It is unclear if oral collagen peptides prevent GI symptoms due to exercise. Details: A small crossover study in moderately well-trained young adults shows that taking collagen peptides 10 grams daily for 7 days prior to rigorous treadmill exercise does not limit GI symptoms but may attenuate some markers of GI distress when compared with placebo (110665).
• Exercise-induced muscle soreness. It is unclear if oral collagen peptides prevent muscle soreness after exercise. Details: Preliminary clinical research in a small number of healthy, recreationally active adults shows that taking collagen peptides (Peptan, Rousselot BVBA, Collagen Peptides, Vital Proteins) 10-15 grams twice daily, starting 7 days prior to strenuous exercise and continuing for 2-5 days after, does not reduce muscle soreness when compared with placebo (100700,104648). However, there was a small benefit on the recovery of countermovement jump ability within 24 hours (104648). Furthermore, another small clinical study in adults unaccustomed to exercise shows that taking collagen peptides 10 grams daily for 33 days modestly reduces muscle soreness and fatigue immediately after the exercise load, but not 2 hours after exercise or the next morning, when compared with placebo (111639). Also, a small clinical study in active middle-aged adults shows that taking specific collagen peptides (SOLUGEL Collagen Peptides, PB Leiner) 10 grams daily for 6 months improves pain in those who exercise frequently (>188 minutes weekly) when compared with placebo. However, collagen peptides do not seem to improve pain in low frequency exercisers (<188 minutes weekly) (112455). Collagen peptides have also been evaluated in combination with other ingredients. One preliminary clinical study in healthy, recreationally active adults shows that taking a specific product (BioCell Collagen, BioCell Technology, LLC) containing collagen peptides from chicken collagen type II, hyaluronic acid, and chondroitin sulfate 1.5 grams twice daily for 6 weeks prior to two bouts of intense resistance exercise attenuates increases in biomarkers of muscle damage and decreases delayed onset muscle soreness when compared with placebo (96301). It is unclear if these benefits are due to collagen peptides, other ingredients or the combination.
• Gingivitis. It is unclear if oral collagen peptides are beneficial for patients with gingivitis. Details: A small clinical study in patients with mild-to-moderate chronic gingivitis shows that taking a specific collagen peptide product (Verisol B, Gelita AG) 5 grams daily for 90 days following mechanical plaque removal reduces bleeding and inflammation but does not improve plaque scores when compared with placebo (110666).
• Hypertension. Limited research suggests that oral collagen peptides may lower systolic or diastolic blood pressure. However, results are inconsistent. Details: One preliminary clinical study in patients with hypertension and type 2 diabetes shows that taking fish-derived collagen peptides 6.5 grams twice daily for 3 months modestly reduces diastolic, but not systolic, blood pressure when compared with placebo (101626). Another small clinical study in patients with mildly elevated blood pressure shows that taking a test food containing chicken leg-derived collagen peptides 2.9 grams daily for 12 weeks lowers systolic, but not diastolic, blood pressure when compared with placebo (101610). An additional small clinical study in patients with mild hypertension shows that taking chicken leg-derived collagen peptides 5.2 grams daily 4 weeks reduces systolic blood pressure by 12 mmHg when compared with baseline (101618). This study was limited by its small size and lack of a comparator group. The reasons for conflicting data are unclear.
• Insomnia. It is unclear if oral collagen peptides are beneficial for insomnia. Details: A very small clinical study in physically active males with difficulty sleeping shows that taking collagen peptides 15 grams before bedtime for 7 nights reduces the frequency of nocturnal awakenings and improves cognitive accuracy but does not improve objective measures of total sleep time, latency, efficiency, stage changes, waking after sleep onset, other cognitive function measures, or subjective measures of sleepiness, fatigue, and sleep quality when compared with placebo (112459).
• Joint pain. Most research shows that oral collagen peptides might moderately reduce joint pain in young athletes. However, evidence in elderly patients is conflicting. Details: Preliminary clinical research in student athletes with joint pain shows that taking a specific collagen peptide product (FORTIGEL, Gelita AG) 10 grams in 25 mL of liquid daily for 24 weeks modestly improves pain during movement and at rest when compared with placebo (101601). Other clinical research in young adults exercising or participating in sports at least 3 hours weekly with activity-related knee pain shows that taking this same product 5 grams daily for 12 weeks reduces pain intensity during activity by 38% to 41%, compared with a 26% to 28% reduction in those taking placebo. However, there was no improvement in pain at rest or after the activity when compared with placebo (97623,107454). Furthermore, it is not clear if these effects are clinically significant. Research on the use of collagen peptides in older patients is conflicting. A small clinical study in otherwise healthy patients aged 40-65 years with joint discomfort shows that taking a specific collagen peptides product (AVC-H2, Avicenna) 1.25 grams twice daily for 8 weeks improves overall Western Ontario and McMaster Universities Osteoarthritis (WOMAC) scores by 37% at 4 weeks, compared with 14% in those receiving placebo. However, this difference in improvement was no longer significant at 8 weeks. Collagen peptides also improved the physical activity and stiffness subdomains, but not the pain subdomain, at 4 and 8 weeks when compared with placebo (107455). A larger clinical study in patients 50 years or older with general joint pain shows that taking a specific collagen peptides product (Genacol) 1200 mg daily for 6 months does not reduce pain or improve function when compared with placebo (97657). However, collagen peptides used in combination with other ingredients have shown benefit. Preliminary clinical research in patients 51-70 years of age shows that taking a specific combination product (Gold Collagen Active, Minerva Research Labs) containing fish collagen peptides 4 grams, glucosamine hydrochloride 1000 mg, chondroitin sulfate 500 mg, L-carnitine 200 mg, and other ingredients daily for 90 days reduces joint pain by 43% when compared with baseline, while patients taking placebo saw negligible improvement in pain. A greater percentage of patients taking this product also perceived improvements in joint discomfort, flexibility, mobility, and rigidity when compared with placebo (100703). It is unclear if these effects are due to collagen peptides, other ingredients, or the combination.
• Obesity. It is unclear if oral collagen peptides are beneficial for weight loss. Details: A preliminary clinical study in adults with overweight shows that taking skate skin-derived collagen peptides 2 grams daily for 12 weeks modestly reduces body fat mass by 1.2 kg, compared with an increase of 0.3 kg in the placebo group (101621). It is unclear if collagen peptides improve weight loss or reduce body fat mass in the long-term.
• Osteoarthritis. Most research suggests that oral collagen peptides improve pain in patients with knee osteoarthritis; however, any improvement is modest and may not be considered clinically significant. Details: A meta-analysis of 3 clinical studies, all of which are included below, in adults with knee osteoarthritis shows that taking collagen peptides or hydrolyzed collagen reduces pain when compared with placebo (112456). Clinical research shows that taking specific collagen peptides (Colnatur, Protein SA) 10 grams daily for 5 months increases the number of patients who experience at least a 30% improvement in pain by approximately 42% when compared with placebo. However, there is no difference between groups when the Western Ontario and McMaster Universities (WOMAC) scale is used. Patients with the greatest joint deterioration at baseline, as well as those with the lowest dietary meat intake, seemed most likely to experience benefit from collagen peptides (97635). Another small clinical study shows that taking collagen peptides isolated from pork skin and bovine bone (Nitta Gelatin Inc.) 5 grams dissolved in 250 mL water or milk twice daily after food for 13 weeks modestly improves pain when compared with placebo (101611). Another small clinical study in patients over 40 years old shows that taking collagen peptides (Colatech) 10 grams daily for 90 days reduces pain by about 2 points on a 100-point scale, compared with a 0.9-point reduction with glucosamine sulfate 1.5 grams. Ibuprofen use was not affected (101622). One multicenter clinical study shows that taking collagen peptides 10 grams daily for 6 months does not relieve pain or improve joint function when compared with placebo, although a trend towards reduced pain and improved joint function was observed in patients with severe symptoms at baseline (7704). Collagen peptides have also been evaluated in combination with other ingredients. Clinical research in patients with osteoarthritis of the knee, hip, or hand shows that taking a specific product (BioCell Collagen, BioCell Technology, LLC) containing collagen peptides from chicken collagen type II, hyaluronic acid, and chondroitin sulfate 1 gram twice daily for up to 10 weeks reduces pain and the need for rescue analgesics and increases physical activity when compared with placebo (28678,28680). Similarly, a moderate-size clinical study in patients aged 45-75 years with mild to moderate knee osteoarthritis undergoing resistance exercise twice weekly shows that taking a specific product (Suntory Beverage and Food Asia) containing collagen peptides from chicken collagen type II, hyaluronic acid, and chondroitin sulfate 2 grams daily for 24 weeks does not improve WOMAC scores when compared with glucosamine 1.5 grams daily or placebo, but may modestly improve pain scores when compared with placebo. However, the use of rescue analgesics was not assessed. Adding essence of chicken 5.81 grams daily to collagen peptides did not improve WOMAC or pain scores (110670). Also, preliminary clinical research in patients with knee osteoarthrosis shows that taking a specific product (Ialoral 1500, PharmaSuisse Laboratories Srl) containing collagen peptides, chondroitin sulfate, hyaluronic acid, and keratin peptides for 4 weeks improves pain and function by a moderate amount when compared with baseline (104645). However, the validity of these findings is limited by the lack of statistical comparison to the control group. It is unclear if these effects are due to collagen peptides, other ingredients, or the combination.
• Osteopenia. It is unclear if oral collagen peptides prevent loss of bone mineral density (BMD) in postmenopausal adults. Details: A large clinical study in patients with reduced BMD after menopause shows that taking specific collagen peptides (Fortibone, Gelita AG) 5 grams daily for 12 months increases BMD of the spine and the femoral neck by 3% and 7%, respectively, compared with losses of 1% with placebo (101609). In a very small observational extension of this study, BMD continued to increase over an additional 4 years when compared with baseline. However, the validity of these findings is limited by the lack of a comparator group (107340). Collagen peptides have also been evaluated in combination with calcium and vitamin D. In patients with osteopenia after menopause, a small clinical study shows that taking collagen peptides calcium chelate 5 grams, containing elemental calcium 500 mg and vitamin D3 200 IU, daily for 12 months does not affect total hip, total body, or vertebral BMD when compared with calcium 500 mg and vitamin D 200 IU (101604). The validity of these results is limited by a high dropout rate and insufficient power to detect smaller effects. Conversely, another small study in this population shows that taking specific collagen peptides (Fortibone, Gelita AG) in combination with elemental calcium (as calcium lactate) 500 mg and vitamin D3 400 IU daily for 12 months improves trabecular bone mineral content, trabecular volumetric BMD, and cortical volumetric BMD, but not cortical bone mineral content, when compared with a combination tablet containing equivalent doses of elemental calcium (as calcium carbonate) and vitamin D (107453). It is unclear if these effects are due to collagen peptides, other ingredients, or the combination.
• Osteoporosis. It is unclear if oral collagen peptides improve bone mineral density (BMD) in adults with osteoporosis after menopause. Details: In patients with osteoporosis after menopause, clinical research shows that taking collagen peptides 10 grams daily in addition to twice weekly intramuscular calcitonin for 6 months does not improve BMD in the forearm when compared with calcitonin alone (104649). It is unclear if supplementation with collagen peptides improves BMD in the femoral neck or lumbar spine.
• Pressure ulcers. Oral collagen peptides might help to improve ulcer size and healing. Details: A small clinical study in patients with Stage II, III, or IV pressure ulcers shows that taking collagen peptides 5 grams orally three times daily for 8 weeks in addition to standard care improves ulcer size and exudate when compared with placebo and standard care (101612). This study was limited because it only used one scale to assess healing of the pressure ulcer. Another small clinical study in patients with stage II or III pressure ulcers shows that receiving standard care and collagen peptides with high levels of prolyl-hydroxyproline 5 grams twice daily for 16 weeks improves ulcer exudate, healing, and wound size when compared with standard care plus placebo (101620).
• Sarcopenia. Oral collagen peptides might help to increase fat-free mass. However, it is unclear if collagen peptides are more beneficial than other types of protein. Details: A small clinical study in elderly males with sarcopenia shows that taking collagen peptides from type I collagen 15 grams daily for 12 weeks along with three resistance training sessions weekly modestly increases fat-free mass and power when compared with resistance training and placebo (101624). It is unclear if supplementation with collagen peptides is more beneficial than supplementation with protein.
• Sprains. It is unclear if oral collagen peptides improve ankle instability after a previous sprain. Details: A small clinical study in athletes with chronic ankle instability from an ankle sprain shows that taking collagen peptides 5 grams daily for 6 months improves subjective ankle instability when compared with placebo. However, ankle stiffness, which is a more objective measure of ankle instability, is not improved when compared with placebo (101603).
• Tendinopathy. It is unclear if oral collagen peptides improve tendon pain. Details: A small clinical study in patients with Achilles tendinopathy shows that taking a specific collagen peptides supplement (TENDOFORTE, Gelita AG) 2.5 grams daily for 3 months in addition to a calf-strengthening program improves pain when compared with baseline (101615). The validity of this finding is limited by the lack of a comparator group.
• Wound healing. It is unclear if oral collagen peptides improve wound healing. Details: A small clinical study in healthy volunteers with wounds after photothermolysis shows that taking collagen peptides 3 grams daily for 4 weeks improves erythema, skin hydration, and skin elasticity when compared with placebo (101599). This study was limited by small size, short duration, and no direct measurement of wound healing or scar formation.
• Wrinkled skin. Some small clinical studies suggest that oral collagen peptides might help to reduce lines and wrinkles from sun damage. Details: Preliminary clinical research in females with photodamaged skin shows that taking a specific low molecular weight collagen peptide product (Evercollagen, Newtree Co.) 1000 mg daily for 12 weeks modestly improves most measures of skin wrinkling, hydration, and elasticity when compared with placebo. This specific collagen peptide product is standardized to contain more than 15% glycine-containing tripeptides, including 3% glycyl-prolyl-hydroxyproline (100702). Another moderate-sized clinical study in adults with dry and wrinkled eye skin shows that taking low-molecular weight collagen peptides (GPVGPS Collagen, Daehan Chemtech) 2000 mg daily for 12 weeks reduces skin wrinkling parameters including facial skin roughness, peak-to-valley values, maximum wrinkle height, and eye wrinkle volume and improves skin hydration and skin elasticity when compared with placebo. However, there was no improvement in maximum wrinkle depth (112458). Another preliminary clinical study shows that taking a specific combination product (BioCell Collagen, BioCell Technology, LLC) containing collagen peptides from chicken collagen type II 600 mg, low molecular weight hyaluronic acid 100 mg, and chondroitin sulfate 200 mg daily for 12 weeks reduces lines and wrinkles associated with both natural aging and photoaging by about 13% when compared to baseline (28681). This study was limited by the lack of a comparator group. Additionally, it is unclear if these effects are due to collagen peptides, other ingredients, or the combination. More evidence is needed to rate collagen peptides for these uses.

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LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

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POSSIBLY SAFE ...when used orally and appropriately, short-term. Collagen peptides have been used with apparent safety at doses up to 10 grams daily for up to 6 months and in doses up to 40 grams daily for up to 4 weeks (97632,97635,101615,101621,104638,104643,104644,104647,101622,110667). PREGNANCY &

LACTATION:
Insufficient reliable information available; avoid using.

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ALUMINUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.  Details Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium reduces the absorption of bisphosphonates.  Details Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Taking calcipotriene with calcium might increase the risk for hypercalcemia.  Details Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.  Details Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.  Details Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.  Details Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of diltiazem.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of dolutegravir.  Details Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of elvitegravir.  Details Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption and effectiveness of levothyroxine.  Details Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.  Details Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption of quinolone antibiotics.  Details Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Calcium may reduce levels of raltegravir.  Details Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium seems to reduce the absorption of sotalol.  Details Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium seems to reduce the absorption of tetracycline antibiotics.  Details Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.  Details Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of verapamil.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

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General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

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General ...Orally, collagen peptides seem to be well tolerated.

Dermatologic ...Orally, a case of a mild skin rash has been reported for a patient who used a specific collagen peptide-containing product (BioCell Collagen) (28680).

Gastrointestinal ...Orally, collagen peptides may cause nausea, dyspepsia, diarrhea, and flatulence, but these adverse effects are rare (101622,104639).

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