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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in healthy adults over 40 years of age with mild forgetfulness shows that taking a specific combination supplement (BGG Japan Co.) containing astaxanthin 9 mg and tocotrienols 50 mg daily for 12 weeks might improve composite and verbal memory when compared with placebo (105099). This study was funded by the supplement manufacturer.
• Age-related macular degeneration (AMD). Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with non-advanced AMD shows that a specific combination product (Azyr, Sifi S.p.A.) containing astaxanthin 4 mg, lutein, zeaxanthin, vitamin E, vitamin C, zinc, and copper, taken daily for 12 months, improves selective dysfunction in the central retina, but does not improve dysfunction in the peripheral retinal areas, when compared with baseline (19196). The validity of this finding is limited by the lack of a comparator group.
• Aging skin. Small studies suggest that oral and topical astaxanthin may be beneficial in aging skin; however, there is conflicting evidence regarding its effects on wrinkles. Details: Small studies in middle-aged adults show that taking astaxanthin (Astavita Astaxanthin, Astavita; AstaReal Oil 50F, Fuji Chemical Industry Co., Ltd.) 2-3 mg orally twice daily for 6-8 weeks improves elasticity, fine lines, wrinkles, and skin moisture when compared with placebo (19561,91734). However, a meta-analysis of small clinical studies in healthy adults shows that taking oral astaxanthin 2-12 mg daily for 4-16 weeks modestly improves moisture content and skin elasticity, but has no effect on wrinkle depth, when compared with placebo (107961). The validity of this meta-analysis is limited due to the population heterogeneity and variety of astaxanthin formulations utilized. In addition to oral astaxanthin, one study also used topical astaxanthin 0.094% (AstaTROL-Hp, Fuij Chemical Industry Co., Ltd.) 1 mL applied twice daily (91734). A systematic review of two very small, nonblinded studies in healthy adults suggests that topical application, either in combination with oral astaxanthin or alone, might have anti-aging skin effects when used for 2-3 weeks (107961).
• Alzheimer disease. Although there is interest in using oral astaxanthin for Alzheimer disease, there is insufficient reliable information about the clinical effects of astaxanthin for this condition.
• Athletic performance. Small studies suggest that oral astaxanthin may improve some aspects of athletic performance. Details: Two small studies in trained cyclists show that taking astaxanthin (Fuji Health Science, Inc. or AstaReal) 4-12 mg daily for 1 or 4 weeks decreases the time to complete a 20-40 km cycling trial by about 50-100 seconds when compared with placebo (91735,105096). However, a larger study in trained cyclists shows that taking astaxanthin (BioReal) 20 mg, vitamin C 300 mg, and vitamin E 50 mg daily for 4 weeks does not decrease time needed to complete a predetermined amount of cycling work (a timed trial) when compared with placebo (91738). Reasons for the discrepancies are not clear but may relate to the fitness level of the athletes in the studies or the differences in timed trial protocols used in the studies.
• Carpal tunnel syndrome. Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a combination of astaxanthin 4 mg, lutein, beta-carotene, and vitamin E (BioAstin, Cyanotech) orally 3 times daily for 8 weeks does not reduce the rate or duration of pain due to carpal tunnel syndrome when compared with placebo (19164).
• Diabetes. It is unclear if oral astaxanthin is beneficial for diabetes. Details: A small clinical trial in adults with diabetes shows that taking astaxanthin (Nature Vision) 8 mg daily for 8 weeks does not reduce levels of cholesterol or fasting blood glucose or reduce diastolic blood pressure when compared with placebo. However, there were some modest beneficial effects on visceral fat, triglyceride level, and systolic blood pressure (109778).
• Dry eye. It is unclear if oral astaxanthin is beneficial for dry eye syndrome. Details: A clinical study in adults and elderly patients with mild to moderate dry eye syndrome shows that taking oral astaxanthin 6 mg twice daily for 30 days improves symptom severity, tear break-up time, fluorescein break-up time, and meibomian gland dysfunction, but not visual acuity or intraocular pressure, when compared with baseline (107962). The validity of these findings is limited by the lack of a comparator group.
• Dyspepsia. It is unclear if oral astaxanthin improves symptoms of dyspepsia. Details: One clinical study in adults with functional dyspepsia with or without Helicobacter pylori infection shows that taking astaxanthin (AstaCarox, AstaReal AB) 16 mg or 40 mg daily for 4 weeks does not reduce indigestion, pain, or H. pylori counts when compared with placebo. However, astaxanthin 40 mg daily may reduce reflux in H. pylori-positive patients (19165).
• Exercise-induced muscle damage. Small clinical studies in trained athletes suggest that oral astaxanthin may not improve markers of muscle damage from exercise. Details: A small study in professional male soccer players shows that taking astaxanthin 4 mg daily for 90 days does not seem to reduce exercised-induced biomarkers of muscle damage, such as creatinine kinase, when compared with placebo (91739). Taking a combination of astaxanthin 4 mg and lutein 480 mg (BioAstin, Cyanotech) daily for 3 weeks also did not reduce creatinine kinase levels after exercise in trained athletes when compared with placebo (safflower oil) (19199).
• Exercise-induced muscle soreness. Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in resistance trained athletes shows that taking a combination of astaxanthin 4 mg and lutein 480 mg (BioAstin, Cyanotech) daily for 3 weeks does not reduce muscle soreness or improve muscle performance 96 hours after exercise when compared with placebo (safflower oil) (19199).
• Fatigue. Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in healthy patients shows that taking a specific combination product (ASTOTS, Fujifilm Co.) containing astaxanthin 6 mg and sesamin 10 mg after breakfast daily for 4 weeks does not improve overall fatigue after completion of mental and physical tasks when compared with placebo (98769).
• Heart failure. Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with heart failure with reduced left ventricular ejection fraction (LVEF) shows that taking a specific supplement containing astaxanthin 12 mg, tocotrienol 40 mg, and L-ascorbic acid 2-glucoside 30 mg (AstaReal ACT, AstaReal Co., Ltd.) daily for 3 months may increase LVEF from 34% to 38% and modestly increase exercise tolerance as measured by the six-minute walk test when compared with baseline (105097). The validity of these findings is limited by the lack of a comparator group. Furthermore, this study was funded by the supplement manufacturer.
• Hyperlipidemia. Small clinical studies suggest that oral astaxanthin is not beneficial for reducing cholesterol levels. Details: One small clinical study in adults with mild hyperlipidemia shows that taking astaxanthin (AstaReal Astaxanthin, Fuji Chemical Industry) 12 mg or 18 mg daily for 12 weeks reduces triglyceride levels, while taking 6 mg or 12 mg daily increases high-density lipoprotein (HDL) cholesterol levels, when compared with placebo. However, total cholesterol and low-density lipoprotein (LDL) cholesterol levels were not affected (19167). Meta-analyses of small clinical studies mostly in adults without hyperlipidemia have also been conducted. One shows that taking astaxanthin 4-18 mg daily for up to 12 weeks does not reduce total or LDL cholesterol levels, but may increase HDL cholesterol levels, when compared with control (105100). A more recent analysis shows that taking astaxanthin 4-20 mg daily for up to 6 months has no beneficial effects on blood lipid levels and might actually increase levels of LDL cholesterol (109776).
• Hypertension. It is unclear if oral astaxanthin reduces blood pressure. Details:A meta-analysis of four small clinical trials shows that taking astaxanthin does not have a clinically beneficial effect on systolic or diastolic blood pressure (109776). However, none of the trials were conducted in patients with hypertension.
• Impaired glucose tolerance (prediabetes). It is unclear if oral astaxanthin is beneficial in patients with prediabetes. Details: A small clinical study in healthy adults and adults with prediabetes shows that taking oral astaxanthin 12 mg daily for 12 weeks improves glycated hemoglobin (HbA1c) when compared with baseline, but not when compared with placebo. Insulin sensitivity and postprandial glucose levels were also improved when compared with baseline, but no statistical comparison to the placebo group was conducted (107965). The validity of this study is limited due to unclear reporting.
• Infertility. It is unclear if oral astaxanthin improves reproductive outcomes in patients with infertility due to endometriosis or polycystic ovary syndrome (PCOS). Details: A small clinical study in adults with infertility secondary to moderate or severe endometriosis undergoing assisted reproductive therapy in Iran shows that taking astaxanthin (AstaReal, AstaReal Co.) 6 mg daily for 12 weeks improves the numbers of oocytes retrieved, mature oocytes, and high-quality embryos but not the quantity of immature oocytes, fertilization rate, number of transferred embryos, or clinical pregnancy rate when compared with placebo (112434). Similarly, a small clinical study also conducted in Iran in patients with infertility due to PCOS undergoing assisted reproductive therapy shows that taking astaxanthin (Algalife Pure astaxanthin) 8 mg daily for 40 days prior to egg retrieval modestly improves the high-quality embryo rate, but not the total number of embryos or the clinical pregnancy rate, when compared with placebo (109775).
• Male infertility. It is unclear if oral astaxanthin improves male infertility. Details: A small low-quality clinical study in males with infertility who are participating in intra-uterine insemination shows that taking astaxanthin (AstaCarox, AstaReal AB) 16 mg daily for 3 months does not seem to increase sperm count and quality, but might result in a higher total pregnancy rate of 23% compared with a 3.6% rate in the placebo group (19197). The validity of this finding is limited by poor study methodology and differences between treatment groups. Another small clinical study in males with infertility and oligospermia shows that taking astaxanthin (Astasan, Sensilab) 16 mg daily does not increase sperm concentration or sperm motility when compared with placebo (105098).
• Menopausal symptoms. Although there is interest in using oral astaxanthin for menopausal symptoms, there is insufficient reliable information about the clinical effects of astaxanthin for this purpose.
• Metabolic syndrome. Although there is interest in using oral astaxanthin for metabolic syndrome, there is insufficient reliable information about the clinical effects of astaxanthin for this condition.
• Nonalcoholic fatty liver disease (NAFLD). Although there is interest in using oral astaxanthin for NAFLD, there is insufficient reliable information about the clinical effects of astaxanthin for this condition.
• Osteoarthritis. Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in adults with mild knee or hip osteoarthritis shows that taking a combination product containing astaxanthin 2 mg, krill oil, and hyaluronic acid daily for 12 weeks (FlexPro MD, Valensa) reduces joint pain and stiffness and improves objective and subjective measures of joint function but does not improve overall physical function when compared with placebo (112432). It is unclear if these effects are due to astaxanthin, other ingredients, or the combination.
• Obesity. Although there is interest in using oral astaxanthin for weight loss, there is insufficient reliable information about the clinical effects of astaxanthin for this purpose.
• Parkinson disease. Although there is interest in using oral astaxanthin for Parkinson disease, there is insufficient reliable information about the clinical effects of astaxanthin for this condition.
• Physical performance. It is unclear if oral astaxanthin improves physical performance in older adults. Details: A small clinical trial in healthy nursing home residents shows that taking astaxanthin (AstaReal) 12 mg twice daily for 16 weeks, in combination with vitamin E 40 mg and vitamin C 30 mg daily, increases the 6-minute walking distance by about 38 meters, a significant increase when compared with placebo containing vitamin E and vitamin C. However, there was no effect on muscle strength (109777). Another small clinical trial in healthy, older adults (aged 65-85 years) undergoing exercise endurance testing shows that a specific combination product (AstaReal; Fuji Health Science, Inc) containing astaxanthin 12 mg, tocotrienol 10 mg, and zinc 6 mg, taken as 2 capsules daily for 12 weeks, reduces the respiratory exchange ratio, but does not improve leg muscle endurance or perceived exertion, when compared with placebo. In a subgroup analysis of males, but not females, those taking astaxanthin had a greater total exercise efficiency when compared with placebo (107963).
• Rheumatoid arthritis (RA). Oral astaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with RA shows that taking a supplement containing astaxanthin 4 mg, lutein 40 mcg, vitamin A 65 IU, vitamin E 50 IU, and safflower oil 460 mg (BioAstin, Cyanotech) three times daily for 8 weeks reduces pain and improves satisfaction by approximately 40% when compared with placebo (94125).
• Stroke. Although there is interest in using oral astaxanthin for recovery from stroke, there is insufficient reliable information about the clinical effects of astaxanthin for this purpose.
• Sunburn. It is unclear if oral astaxanthin might help to prevent sunburn. Details: A very small clinical study in Japanese adults shows that taking astaxanthin (Astots, Fujifilm Corporation) 4 mg daily for 9 weeks might increase skin tolerance to ultraviolet (UV) light when compared with placebo (96884). It is unclear if this translates to a lower risk of sunburn. More evidence is needed to rate astaxanthin for these uses.

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POSSIBLY EFFECTIVE

• Age-related macular degeneration (AMD). When used alone or in combination with other ingredients, oral lutein seems to improve some aspects of vision in patient with AMD. However, it does not seem to slow the progression of AMD. Details: Epidemiological research has found that people who consume higher amounts of lutein plus zeaxanthin in the diet have a reduced risk of developing AMD (219,2394,60238,106353). The association between intake of lutein specifically and the development of AMD is not clear; however, dietary lutein levels are much higher than dietary zeaxanthin levels. Although one study found no association between increased dietary lutein consumption and a reduced risk for age-related maculopathy, people in this study already had high lutein intake at baseline (14007). Some research has assessed whether lutein supplements can reduce symptoms and progression of existing AMD. Clinical research, including pooled analyses, in adults with AMD shows that taking supplemental lutein 10-20 mg daily for up to 36 months modestly improves some aspects of vision, such as macular pigment optical density, the ability of the eyes to adapt to varying light conditions (glare recovery), the ability to see details of near objects (near vision acuity), and the ability to see under low-contrast conditions (contrast sensitivity) (11798,48213,60185,60242,60245,60268,60270,60280,90678,91160)(91165,97225,102887,106366). Meta-analyses of these and other studies shows that taking lutein or a related xanthophyll carotenoid (zeaxanthin or meso-zeaxanthin) improves macular optical density when compared with placebo in patients with or without AMD. Treatment duration of at least 3 months, doses greater than 5 mg, and/or combination treatment with all three carotenoids are associated with a greater improvement in macular optical density (97225,106366). However, lutein supplements do not appear to affect the progression of AMD (60281). A meta-analysis of 6 studies shows that taking lutein supplements for 0.5-5 years does not reduce the risk of visual loss or progression to late-stage AMD when compared with placebo (95839). Lutein has also been evaluated in combination with other ingredients, with conflicting findings. Although not all research agrees, lutein-containing combination supplements might improve some symptoms of AMD (19196,60134,60180,60207,60237,60244,97226). A specific supplement (AZYR SIFI) containing lutein 10 mg, vitamin C 180 mg, vitamin E 30 mg, zinc 22.5 mg, copper 1 mg, zeaxanthin 1 mg, and astaxanthin 4 mg has been used daily for 1-2 years in some research with moderate evidence of benefit (19196,60244). Taking lutein 10 mg plus zeaxanthin 2 mg in addition to the original Age-Related Eye Disease Study (AREDS) formulation (vitamins C and E, beta carotene, and zinc) does not seem to prevent the progression to advanced AMD more than the AREDS formulation alone. However, this progression was modestly inhibited in individuals with low dietary intakes of lutein and zeaxanthin. While progression to late AMD was only modestly inhibited at 5 years when these doses of lutein and zeaxanthin were included in a revised formulation devoid of beta-carotene (AREDS2) (60281), results of an additional 5 years of follow up showed that this revised formulation reduces the risk of progression to late AMD by 15% when compared with the formulation containing beta-carotene (108615). In first-generation offspring of parents with neovascular AMD, taking lutein 10 mg, zeaxanthin 2 mg, vitamin C 180 mg, vitamin E 30 mg, zinc 15 mg, and copper 1 mg daily for 6 months does not improve the macular pigment optical density (106347). Reasons for these discrepancies are not clear but may relate to lutein dose, dietary lutein intake, treatment duration, or the other ingredients included in the combination products.
• Cataracts. Increased dietary lutein seems to reduce the odds of developing cataracts. It is unclear if oral lutein supplementation is beneficial in those who already have cataracts. Details: Observational research and a meta-analysis of this evidence suggests that higher blood levels and/or higher dietary intake of lutein are associated with a 25% lower odds of developing age-related cataracts, and more specifically, a 25% to 27% decreased risk of developing nuclear cataracts (90944,91161,91162,112095). Population research has also found that people who consume higher amounts of lutein (6.9-11.7 mg daily) as part of their diet have a reduced risk of developing severe cataracts that require surgical removal (2395,3219,3220). Clinical research shows that taking lutein 10 mg and zeaxanthin 2 mg per day orally for an average of 4.7 years decreases the risk of needing cataract surgery by 32% in patients with low dietary intake of lutein and zeaxanthin; however, it doesn't benefit patients with higher dietary intake of lutein and zeaxanthin (94703). Some evidence shows that supplemental lutein might benefit patients who already have cataracts. Preliminary clinical research in adults with grade 2 or 3 senile cataracts shows that taking lutein 15 mg orally three times weekly for up to 2 years can improve the ability to see clearly when compared to baseline (60133).

POSSIBLY INEFFECTIVE

• Bronchopulmonary dysplasia. Oral lutein does not seem to prevent bronchopulmonary dysplasia in preterm and low birth weight infants. Details: Clinical research shows that giving preterm and low birth weight infants a specific product (LUTEINofta, SOOFT Italia SpA) containing lutein 0.14 mg and zeaxanthin 0.0006 mg orally once daily, starting at birth and continuing until 36 weeks corrected gestational age, does not decrease the incidence of bronchopulmonary dysplasia when compared with placebo (91163).
• Necrotizing enterocolitis (NEC). Oral lutein does not seem to prevent NEC in preterm and low birth weight infants. Details: Clinical research shows that giving preterm and low birth weight infants a specific product (LUTEINofta, SOOFT Italia SpA) containing lutein 0.14 mg and zeaxanthin 0.0006 mg orally once daily, starting at birth and continuing until 36 weeks corrected gestational age, does not decrease the incidence of NEC when compared with placebo (91163).
• Retinitis pigmentosa. Oral lutein does not seem to improve vision or slow down retinal degeneration in patients with this condition. Details: While some preliminary clinical evidence suggests that oral lutein might be helpful in the treatment of retinitis pigmentosa (10279), most clinical research shows that taking lutein does not improve vision or other markers of retinal degeneration in patients with retinitis pigmentosa (60117,60165,60225).
• Retinopathy of prematurity. Oral lutein does not seem to prevent retinopathy of prematurity in preterm and low birth weight infants. Details: Clinical research in preterm and low birth weight infants shows that giving 0.5 mL or 1.8 mL/kg of a specific product (LUTEINofta, SOOFT Italia SpA) providing lutein 0.14 mg, or giving 0.5 mg/kg plus zeaxanthin 0.0006 mg or 0.02 mg/kg orally once daily, starting at birth and continuing until 36-40 weeks corrected gestational age, does not decrease the incidence or severity of retinopathy of prematurity when compared with placebo (60240,60243,91163,102889).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral lutein is beneficial for attenuating cognitive decline in older adults. Details: Clinical research in adults 40-75 years old shows that taking lutein 10 mg with zeaxanthin 2 mg daily for 6 months improves some, but not all, measures of visual memory when compared with placebo. However, other measures of memory and cognitive function were not improved (109763). Preliminary clinical research in older adults shows that taking the same dose of lutein and zeaxanthin for one year modestly improves some measures of cognitive function, such as complex attention and cognitive flexibility, when compared with placebo (106367). Other preliminary clinical research in older females shows that taking lutein 12 mg alone or with docosahexaenoic acid (DHA) 800 mg daily for 4 months can improve verbal fluency and memory scores when compared to baseline (48216). Also, some observational research in patients 50 years and older has found that higher dietary lutein and zeaxanthin intake is associated with greater word recall when compared with lower intake (102891). However, clinical research in patients over 60 years old shows that taking lutein 10 mg with zeaxanthin 2 mg daily for 5 years in addition to vitamins C and E, beta-carotene, and zinc (AREDS) does not improve markers of cognitive function, such as memory and verbal fluency, when compared with AREDS alone (94702). More research is needed to determine whether lutein is beneficial for specific measures of cognitive function in older adults.
• Alzheimer disease. Oral lutein has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with mild to moderate Alzheimer disease shows that taking lutein 10 mg, zeaxanthin 2 mg, meso-zeaxanthin 10 mg, fish oil 1 gram (providing docosahexaenoic acid 500 mg and eicosapentaenoic acid 150 mg), and vitamin E 15 mg (Memory Health) daily for 12 months does not affect disease severity when compared with placebo. However, there were modest increases the number of patients experiencing either an improvement or an attenuated decline in memory and mood (109764). The effect of lutein alone is unclear.
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). It is unclear if oral lutein is beneficial for ALS prevention. Details: Population research has found that higher dietary intake of lutein is associated with a 21% lower risk of developing ALS when compared with lower dietary intake (90412). It is unknown if supplemental lutein has any effect on the risk of developing ALS.
• Asthenopia (eye strain). It is unclear if oral lutein is beneficial for eye strain. Details: Preliminary clinical research shows that some combination lutein supplements might reduce symptoms of eye strain. Results from one clinical trial show that taking a combination product containing lutein, zeaxanthin, and black currant extract daily for 2 weeks improves visual fatigue and eye stress when compared with placebo in patients completing a two-hour visual proof reading task (60214). Other clinical research shows that taking lutein 17.5 mg plus omega-3 fatty acids (standardized to contain docosahexaenoic acid 783 mg and eicosapentaenoic acid 162 mg) and bilberry extract (standardized to contain anthocyanidin 59 mg) daily for 4 weeks reduces symptoms of eye strain when compared with placebo (35470). The effect of lutein alone on eye strain is unclear.
• Asthma. It is unclear if oral lutein is beneficial for asthma prevention. Details: Population research has found that a higher dietary intake of lutein plus zeaxanthin is associated with up to 30% lower odds of having asthma when compared with a lower dietary intake (109765). The effects of lutein intake alone or lutein supplementation are unclear.
• Cardiovascular disease (CVD). Eating more lutein in the diet seems to reduce the risk of CVD. However, taking oral lutein supplements does not seem to prevent CVD events or mortality. Details: One observational study has found that increased intake of dietary lutein is marginally associated with a reduced risk of developing coronary heart disease (14108). A meta-analysis including this and other studies shows that high dietary lutein intake or high lutein serum concentrations are associated with a 12% reduction in the incidence of coronary heart disease, an 18% reduction in stroke, and a 25% reduction in the incidence of metabolic syndrome when compared with low lutein intake or serum concentrations (97227). However, clinical research shows that taking lutein 10 mg plus zeaxanthin 2 mg daily for an average of 4.8 years does not decrease the risk of CVD-related mortality or cardiovascular events such as stroke, myocardial infarction, or angina when compared with no supplementation in patients 50-85 years old (94701). Unlike the analysis above, individual cardiovascular outcomes were not separately evaluated in this study. The effect of lutein on CVD in younger patients or in doses greater than 10 mg is unknown.
• Central serous retinopathy. Oral lutein has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a supplement containing lutein 15 mg, vitamin C 288 mg, vitamin E 150 IU, zinc 9 mg, and copper 1.2 mg (Sante Lutax 15, Santen Pharmaceutical Co. Ltd) three times daily after meals for 6 months has no effect on mean best-corrected visual acuity, serous retinal detachment, or subfoveal fluid remission when compared with placebo in patients with central serous retinopathy (97224).
• Cervical cancer. It is unclear if oral lutein is beneficial for cervical cancer prevention. Details: Epidemiological research has found that low dietary intake of lutein is not associated with an increased risk for developing cervical cancer (60297).
• Child development. It is unclear if oral lutein is beneficial for child development. Details: Epidemiological research has found that a higher dietary intake of lutein in the first and second trimesters of pregnancy is associated with increased verbal intelligence and improved behavior in the child at 6-10 years of age. However, the ability to discriminate between a novel or familiar visual stimulus was reduced at about 6 months of age, and there were no effects on most cognitive outcomes in children aged 3-6 years (107106). Other epidemiological research has found that a higher dietary intake of lutein plus zeaxanthin in children aged 3-6 years may be associated with modestly improved executive function at 6-10 years. However, there were no effects on most cognitive outcomes in children aged 3-6 years or 6-10 years (109761).
• Choroideremia. It is unclear if oral lutein is beneficial for improving vision. Details: Preliminary clinical research shows that taking lutein 20 mg daily for 6 months does not improve vision in patients with choroideremia (60124).
• Cognitive function. It is unclear if oral lutein is beneficial for improving cognitive function. Details: A meta-analysis of clinical research shows that increased dietary lutein does not improve cognitive function measures, such as attention, executive function, or memory, when compared with placebo or an isocaloric meal (107082). However, the dietary source of lutein used in the included studies was heterogeneous and any conclusions remain unclear. Doses of lutein ranged from 8-12 mg daily, alone or in combination with daily zeaxanthin 2-26 mg and/or meso-zeaxanthin 10 mg and docosahexaenoic acid (DHA) 800 mg (107082). However, some preliminary clinical research in younger adults shows that taking lutein 10 mg and zeaxanthin 2 mg for one year modestly improves some measures of cognitive function, such as spatial memory, when compared with placebo (106348). Also, observational research has found that intake of choline and lutein plus zeaxanthin is positively associated with cognitive flexibility task performance speed. However, this association is not present with the intake of lutein plus zeaxanthin in the absence of choline (106354). Reasons for these discrepancies are not clear but may relate to lutein dose, treatment duration, or the addition of other nutrients to the diet or supplements.
• Colorectal cancer. It is unclear if oral lutein is beneficial for colorectal cancer prevention. Details: Some epidemiological research has found that higher dietary intake of lutein is associated with a reduced risk of developing colon cancer (3962). However, most epidemiological research has found that higher dietary intake of lutein is not associated with a reduced risk of colorectal cancer (34481,106372). It is not known if supplemental lutein has any effect on colorectal cancer risk.
• Depression. It is unclear if oral lutein is beneficial for depression. Details: A cross-sectional study in 8655 adults with cardiometabolic disease including diabetes, hypertension, coronary heart disease, heart failure, and stroke suggests that higher dietary lutein and zeaxanthin intake is associated with a 31% reduced risk of depression when compared with lower dietary intake. The study also found that adults with depression had lower dietary lutein and zeaxanthin intake than those without depression. Additionally, the study found a nonlinear U-shaped relationship between total dietary carotenoid intake and the risk of depression among patients with cardiometabolic disease, where the risk of depression decreased with increasing total dietary carotenoid intake up until an inflection point where the risk of depression increased with increasing total dietary carotenoid intake (112098). Further research is needed to establish causality.
• Diabetes. Observational research suggests that oral lutein may not be beneficial for the prevention of diabetes or diabetic complications. Details: Some epidemiological research has found that low serum levels of carotenoids, including lutein, are associated with impaired glucose tolerance. This may indicate that taking carotenoids such as lutein might reduce the risk of diabetes development (60161). However, population research has found that increasing intake of dietary lutein plus zeaxanthin does not decrease the risk of developing type 2 diabetes (14004,97227). Other epidemiological research in patients with type 2 diabetes has found that an increased serum concentration of lutein is not associated with reduced cardiovascular mortality over 14 years (109768).
• Diabetic retinopathy. It is unclear if oral lutein is beneficial in diabetic retinopathy. Details: Preliminary clinical research shows that taking lutein 10 mg daily for 36 weeks has no effect on visual acuity or glare sensitivity in patients with non-proliferative diabetic retinopathy (97223). Observational research in a small group of patients with non-proliferative diabetic retinopathy has also found that taking lutein 4 mg with zeaxanthin 0.5 mg daily for 4 months does not improve visual acuity, contrast sensitivity, or glare sensitivity when compared with zeaxanthin alone (100986).
• Esophageal cancer. It is unclear if oral lutein is beneficial for esophageal cancer prevention. Details: Population research has found that people who consume higher amounts of lutein and zeaxanthin in their diet have a 29% lower risk of developing esophageal squamous cell cancer when compared with those with lower intake (91159). It is unknown if supplemental lutein has any effect on esophageal cancer risk.
• Exercise-induced muscle soreness. It is unclear if oral lutein is beneficial in relieving muscle soreness due to exercise. Details: Some clinical research shows that taking a specific lutein-containing combination product (BioAstin, Cyanotech Corp.) containing haematococcus algae extract with astaxanthin 4 mg and lutein 480 mg daily for 3 weeks prior to exercise does not significantly reduce post-exercise muscle soreness when compared with placebo (19199). The effect of lutein alone is unclear.
• Fractures. It is unclear if oral lutein is beneficial for fracture prevention. Details: A meta-analysis of observational research has found that increased dietary intake of lutein and/or zeaxanthin is not associated with a reduced risk of hip fractures (97228).
• Gastric cancer. It is unclear if oral lutein is beneficial for gastric cancer prevention. Details: A meta-analysis of observational research has found that increased dietary intake of lutein and/or zeaxanthin is not associated with a reduced risk of developing gastric cancer (97231).
• Glaucoma. Oral lutein has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with open-angle glaucoma shows that taking oral lutein 10 mg, zeaxanthin 2 mg, and meso-zeaxanthin 10 mg daily for 18 months increases macular pigment density, but does not affect visual function, when compared with placebo (109756).
• Hyperlipidemia. It is unclear if oral lutein is beneficial for hyperlipidemia. Details: A meta-analysis of clinical research shows that supplementation with lutein does not reduce the levels of total, low-density lipoprotein (LDL), or high-density lipoprotein (HDL) cholesterol when compared with placebo (109757). Most publications included in this analysis evaluated lutein alone in healthy adults or in patients with age-related macular degeneration, two studies combined lutein with another ingredient, and one study evaluated zeaxanthin alone. The effect of lutein in patients with existing hyperlipidemia is unclear.
• Infertility. It is unclear if oral lutein is beneficial for infertility. Details: An observational study suggests that there is no association between dietary lutein intake and in-vitro fertilization (IVF) outcomes including good oocyte quality, embryo transfer success rates, clinical pregnancy rates, and successful term pregnancy rates in subfertile couples who are candidates for IVF (112097).
• Lung cancer. Research is conflicting whether oral lutein is beneficial for lung cancer prevention. Details: Epidemiological research has found that low serum levels of carotenoids, including lutein, are associated with an increased risk of lung cancer (12874). However, other epidemiological research has found that higher serum levels or higher dietary intake of lutein are not associated with a reduced risk of developing or dying from lung cancer (39690,60090,60160). Another large epidemiological cancer screening trial with a mean follow-up of over 12 years suggests that dietary intake of lutein and zeaxanthin is protective against lung cancer as shown by a non-linear dose response curve, where lower doses of lutein and zeaxanthin are associated with a sharp decrease in the incidence of lung cancer, followed by a more gradual decrease in incidence at higher doses (112096).
• Macular telangiectasia type 2. It is unclear if oral lutein is beneficial for macular telangiectasia type 2. Details: In patients with macular telangiectasia type 2, observational research has found that taking a specific combination of lutein 10 mg, meso-zeaxanthin 10 mg, and zeaxanthin 2 mg (MacuShield; Alliance Pharmaceuticals) for at least 6 months, with an average duration of 15.7 months, was associated with a stabilization of visual acuity. Also, the number and size of cavitations in the macula were reduced (106355).
• Metabolic syndrome. Oral lutein has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of observational research shows that high dietary lutein intake or high lutein serum concentrations are associated with a 25% reduction in the incidence of metabolic syndrome when compared with low lutein intake or serum concentrations (97227). Additional population research in females shows that the highest dietary intake of lutein plus zeaxanthin is associated with 54% reduced odds of developing metabolic syndrome when compared with the lowest intake. However, when supplements containing lutein plus zeaxanthin were included in the total intake, there was no association with metabolic syndrome (109760).
• Myopia. It is unclear if oral lutein is beneficial for myopia. Details: A very small clinical study in adults aged 20-50 years with high myopia shows that taking lutein 20 mg daily for 6 months does not improve macular pigment optical density, visual acuity, contrast sensitivity, or electroretinogram measurements when compared with placebo (112099). The validity of these findings is limited by the very small sample size and short study duration.
• Non-Hodgkin lymphoma. It is unclear if oral lutein is beneficial for Non-Hodgkin lymphoma prevention. Details: A meta-analysis of observational population research has found that increased intake of lutein/zeaxanthin in the diet is associated with an 18% lower risk of developing non-Hodgkin lymphoma when compared with low dietary intake. However, no dose-response relationship was reported (97229). It is unknown if supplemental lutein has any effect on non-Hodgkin lymphoma risk.
• Obesity. It is unclear if oral lutein is beneficial for obesity. Details: A small clinical trial in obese middle-aged individuals shows that taking lutein 20 mg daily in addition to following a low-calorie diet for 10 weeks does not affect most anthropometric or cardiometabolic indices when compared with a low-calorie diet alone. However, there was a small beneficial effect on body fat and total cholesterol levels (107107).
• Pancreatic cancer. It is unclear if oral lutein is beneficial for pancreatic cancer prevention. Details: A meta-analysis of population research has found that increased dietary intake of lutein and/or zeaxanthin is not associated with a reduced risk of pancreatic cancer (97230). The effects of supplemental lutein are unclear.
• Parkinson disease. It is unclear if oral lutein is beneficial for Parkinson disease prevention. Details: Population research has found that higher dietary intake of lutein is not associated with the risk of developing Parkinson disease (91164). The effects of supplemental lutein are unclear.
• Pre-eclampsia. It is unclear if oral lutein is beneficial for pre-eclampsia prevention. Details: Some epidemiological research has found that high plasma concentrations of lutein are associated with a decreased risk of pre-eclampsia (60142). Other epidemiological research has found that the highest dietary intake of lutein plus zeaxanthin during pregnancy is associated with 68% reduced odds of having pre-eclampsia when compared with the lowest intake (109762). The effects of lutein supplements are unclear.
• Respiratory tract infections. It is unclear if oral lutein is beneficial in respiratory tract infection prevention or treatment. Details: Epidemiological research has found that high serum levels of lutein are not associated with a decreased incidence or severity of respiratory tract infections in the elderly (60152). The effects of supplemental lutein are unclear.
• Ulcerative colitis. It is unclear if oral lutein is beneficial for ulcerative colitis. Details: In patients in the remission phase of ulcerative colitis, observational research has found that a higher dietary intake of lutein plus zeaxanthin is associated with a reduced incidence of constipation, but not flatulence or feelings of urgency (tenesmus) (106362). The effects of supplemental lutein are unclear.
• Visual development. It is unclear if taking oral lutein during pregnancy can improve the visual acuity of the child. Details: Some observational research has found that higher maternal lutein levels are associated with a 22% to 40% lower risk of poor visual acuity in children at 3 years of age when compared with lower maternal lutein levels (102888). However, other epidemiological research has found that dietary intake of lutein plus zeaxanthin during the first or third trimesters of pregnancy is not associated with contrast vision or visual acuity in the child at 11-12 years of age (109759). The effects of lutein supplements are unclear. More evidence is needed to rate lutein for these uses.

(Read more about LUTEIN)

EFFECTIVE

• Ariboflavinosis. Oral riboflavin can treat and prevent low riboflavin levels.

POSSIBLY EFFECTIVE

• Hyperhomocysteinemia. Oral riboflavin reduces homocysteine levels in individuals with the MTHFR 677 TT genotype. It does not seem to provide benefit in individuals with other genotypes. Details: Population research has found that poor riboflavin status is associated with high homocysteine levels in individuals with the 677 TT genotype for the MTHFR enzyme (71386,71403,71409). Taking riboflavin 1.6 mg daily for 12 weeks reduces homocysteine levels by 22% to 40% in individuals with the 677 TT genotype of MTHFR when compared with pretreatment. However, riboflavin supplementation does not seem to reduce homocysteine levels in individuals with the 677 CC or CT genotypes (71443).
• Migraine headache. Oral riboflavin modestly reduces migraine attack frequency and severity in adults. The benefits of oral riboflavin in children are unclear. Details: A meta-analysis of 5 small clinical trials in adults with migraine shows that taking riboflavin 100-400 mg daily, alone or in combination with other natural ingredients, for three months modestly reduces migraine duration, frequency, and pain scores when compared with control (105480). These findings are limited by significant heterogeneity. Most clinical studies compared riboflavin 400 mg daily with placebo, no treatment, or an active control (1396,1397,1398,12387,105480). Limited evidence also suggests that taking riboflavin 400 mg daily might be no different for migraine prevention than certain conventional treatments such as bisoprolol 10 mg, metoprolol 200 mg, propranolol 80 mg, or valproate 500 mg (1396,105480). These findings are limited due to small study size and a lack of power to detect a difference between groups. Limited research has also evaluated riboflavin in children. A network meta-analysis of 3 small clinical trials in children with migraine shows that taking oral riboflavin 100-200 mg daily for 4-12 months does not significantly reduce incidence of migraine when compared with placebo. However, there was a non-significant trend towards reduced migraine frequency. Furthermore, conventional treatments such as propranolol, pregabalin, valproate, and topiramate were not shown to be significantly better than riboflavin for migraine prevention (105484). These findings are limited by small population sizes and insufficient power to detect differences between groups. Although riboflavin 100-200 mg has been used in prospective clinical studies, small observational studies have found some benefit in children taking riboflavin doses as low as 10-40 mg daily and as high as 400 mg daily for 3-4 months (105481,105485). Riboflavin has also been studied in combination with other ingredients, with research suggesting potential benefit. Specifically, riboflavin 400 mg has been combined with magnesium 600 mg and coenzyme Q10 150 mg daily (Dolovent; Linpharma Inc.) (92101), and also with magnesium 300 mg and feverfew 100 mg daily (12389).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there is interest in using oral riboflavin for acne, there is insufficient reliable information about the clinical effects of riboflavin for this purpose.
• Alzheimer disease. Although there is interest in using oral riboflavin for Alzheimer disease, there is insufficient reliable information about the clinical effects of riboflavin for this condition.
• Cardiovascular disease (CVD). It is unclear if oral riboflavin can prevent mortality due to CVD. Details: Epidemiological research has found that dietary and supplemental riboflavin intake in the highest quartile, around 3.4 mg daily, is associated with a 47% lower risk of CVD mortality when compared with riboflavin intake in the lowest quartile, around 1 mg/day. The reduction in CVD mortality with riboflavin was enhanced by higher folate intake (110727). The validity of this finding is limited by the fact that dietary riboflavin intake was based on 2-day dietary recall.
• Carpal tunnel syndrome. Although there is interest in using oral riboflavin for carpal tunnel syndrome, there is insufficient reliable information about the clinical effects of riboflavin for this purpose.
• Cataracts. It is unclear if oral riboflavin is beneficial in patients with cataracts. Details: Observational research has found that high dietary intake of riboflavin is associated with a reduced risk of nuclear cataracts and age-related lens opacification (6378,14301). Furthermore, a clinical study in Chinese patients with nutrient deficiencies shows that taking a combination of riboflavin 3 mg plus niacin 40 mg daily also seems to reduce the risk of developing nuclear cataracts when compared with no supplementation (4885). It is unclear if the benefit is due to riboflavin, niacin, or the combination.
• Cervical cancer. It is unclear if oral riboflavin helps to prevent cervical cancer. Details: Epidemiological evidence has found that increased riboflavin intake from dietary and supplement sources, along with other B vitamins, is associated with a reduced risk of precancerous cervical lesions (11074).
• Colorectal cancer. It is unclear if oral riboflavin reduces colorectal cancer risk. Details: Epidemiological evidence in a Chinese population has found that increased dietary intake of riboflavin is associated with a reduced risk of developing colorectal cancer (105482).
• Diabetic neuropathy. Intravenous and oral riboflavin have only been evaluated in combination with other ingredients; riboflavin's effect when used alone is unclear. Details: Clinical research in patients with type 2 diabetes shows that intravenous administration of a specific combination product containing succinic acid, inosine, nicotinamide, and riboflavin (Cytoflavin, Polysan) daily for 10 days followed by an oral formulation of the same product, taken daily for 76 days, reduces symptoms of diabetic neuropathy including paresthesia, numbness, and burning when compared with placebo (110503). It is unclear if these findings are due to riboflavin, other ingredients, or the combination.
• Esophageal cancer. It is unclear if oral riboflavin reduces esophageal cancer risk. Details: Population research in Iranian patients has found that low riboflavin status is associated with a two-fold increase in the risk of esophageal cancer (71439). However, not all evidence agrees. Preliminary clinical studies in Chinese individuals with esophageal dysplasia shows that taking riboflavin, alone or in combination with calcium or niacin, for 3-5 years does not seem to reduce the risk of esophageal cancer in patients when compared with baseline or control (4679,63576,71488). Taking riboflavin 200 mg weekly, in combination with retinol 15 mg and zinc 50 mg, also does not seem to be beneficial in this patient population (71501). It is unclear if these findings are generalizable to geographic locations other than China and Iran.
• Gastric cancer. It is unclear if oral riboflavin reduces colorectal cancer risk. Details: Low quality clinical research in a Chinese population shows that taking riboflavin in combination with niacin does not appear to reduce the risk of gastric cancer when compared with control (4679).
• Hypertension. There is limited evidence on the oral use of riboflavin for reducing blood pressure in patients with the MTHFR 677 TT genotype. Details: A 677 C to T polymorphism on the MTHFR gene has been associated with hypertension. In patients with a confirmed MTHFR 677 TT genotype and premature cardiovascular disease, preliminary clinical research suggests that taking riboflavin 1.6 mg daily for 16 weeks reduces systolic blood pressure (SBP) by 9 mmHg and diastolic blood pressure (DBP) by 6 mmHg when compared with placebo . This decrease in blood pressure is larger than that reported in other trials, which may be due to the fact that only patients with the 677 TT genotype were included. These patients seem to respond to riboflavin therapy more so than patients with 677 CC or 677 CT genotype (92102). Additional clinical research in patients with the 677 TT genotype but without cardiovascular disease shows that taking riboflavin 1.6 mg daily for 16 weeks reduces SBP by 5.6 mmHg but does not reduce DBP (92103). There is also interest in using dietary riboflavin for reducing the onset of hypertension. Some epidemiological evidence in a Chinese population has found that increased dietary intake of riboflavin is associated with a reduced risk of developing hypertension (105483).
• Liver cancer. Oral riboflavin has only been evaluated in combination with niacin; its effect when used alone is unclear. Details: Preliminary clinical research in Chinese individuals older than 55 years shows that taking riboflavin in combination with niacin does not seem to prevent liver cancer mortality when compared with control. However, there was a reduced risk of liver cancer mortality in people aged less than 55 years when compared with control (63470).
• Lung cancer. Oral riboflavin has only been evaluated in combination with niacin; its effect when used alone is unclear. Details: Preliminary clinical research in Chinese individuals shows that taking riboflavin in combination with niacin does not appear to reduce the risk of lung cancer when compared with control (34539).
• Malaria. Oral riboflavin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in children ages 5-14 years living in Gambia and at high risk for malaria exposure suggests that taking riboflavin, in combination with iron, thiamine, and vitamin C, for 3 months does not reduce the frequency or severity of malaria infections when compared with placebo (56730).
• Malnutrition. There is limited evidence on the oral use of riboflavin with other ingredients in children at risk for kwashiorkor. Details: A clinical study in Malawian children at risk for kwashiorkor, a severe form of malnutrition, suggests that taking riboflavin, vitamin E, selenium, and N-acetyl cysteine at a dose of three times the recommended dietary allowance does not prevent kwashiorkor, reduce edema, increase physical growth, or reduce infection when compared with placebo (71433).
• Mitochondrial myopathies. Although there is interest in using oral riboflavin for mitochondrial myopathies, there is insufficient reliable information about the clinical effects of riboflavin for this condition.
• Multiple sclerosis (MS). It is unclear if oral riboflavin slows the progression of MS-related disability. Details: A small clinical study in patients with relapsing-remitting MS or secondary progressive MS who are undergoing treatment with disease-modifying therapies suggests that taking oral riboflavin 10 mg daily for six months is no more effective for improving disability than placebo (91752). The validity of this finding is limited by the small study sample size.
• Oral leukoplakia. It is unclear if oral riboflavin prevents or slows progression of oral leukoplakia. Details: Population research in people living in Uzbekistan has found that low blood levels of riboflavin are associated with an increased prevalence of oral leukoplakia (71502). However, clinical evidence in patients with a high occurrence of oral and esophageal cancer who are living in Uzbekistan suggests that taking riboflavin 80 mg weekly for 20 months does not improve the prevalence or progression of oral leukoplakia when compared to baseline (71565). The validity of this finding is limited by the lack of a placebo group and unusual once weekly dosing. Furthermore, it is unclear if these results are generalizable to other geographic locations.
• Pre-eclampsia. Although there is interest in using oral riboflavin for pre-eclampsia, there is insufficient reliable information about the clinical effects of riboflavin for this purpose.
• Pregnancy-related iron deficiency. It is unclear if oral riboflavin is beneficial in patients with iron deficiency due to pregnancy. Details: Preliminary clinical research in pregnant patients in China suggests that adding riboflavin 1 mg daily to supplemental iron and folic acid does not improve iron status when compared with taking iron and folic acid alone (71480).
• Sickle cell disease. It is unclear if oral riboflavin is beneficial in patients with sickle cell disease. Details: One small clinical study in patients with sickle cell disease suggests that taking riboflavin 5 mg twice daily for 8 weeks increases serum iron and transferrin saturation when compared to baseline; however, riboflavin does not seem to improve serum ferritin or circulating hemoglobin levels (71566).
• Stroke. Oral riboflavin has only been evaluated in combination with niacin; its effect when used alone is unclear. Details: Preliminary clinical research in Chinese individuals with poor nutritional status who are at risk for stroke suggests that taking riboflavin 5.2 mg daily in combination with niacin 40 mg daily does not reduce the risk of stroke-related mortality (2673). More evidence is needed to rate riboflavin for these uses.

(Read more about RIBOFLAVIN)

POSSIBLY EFFECTIVE

• Age-related macular degeneration (AMD). Oral zeaxanthin, when used in low levels as part of multi-ingredient products containing lutein, seems to improve some aspects of vision in patient with AMD. It is unclear if oral zeaxanthin alone or in amounts similar to lutein is beneficial for slowing AMD progression. Details: Epidemiological research has found that people who consume higher amounts of zeaxanthin plus lutein in the diet have a reduced risk of developing late AMD, but not early or intermediate AMD (60238,106353,106359). However, any association between intake of zeaxanthin itself and the development of AMD is not clear. Some clinical research has assessed whether zeaxanthin alone can reduce symptoms and progression of AMD. A small clinical trial shows that taking supplemental zeaxanthin 8 mg daily for 12 months modestly improves some aspects of vision, such as macular pigment optical density, the ability to see details of near objects (near vision acuity), and resolution of scotoma (blind spot), when compared with placebo in patients with AMD (60245). Other clinical research in a healthy population shows that taking zeaxanthin alone (Optisharp) as 10 mg daily for 6-12 months increases macular pigment optical density (60175). Most clinical research in patients with AMD has assessed zeaxanthin in combination with lutein. In general, this combination has been shown to increase macular pigment optical density, as well as the ability to see under low-contrast conditions (contrast sensitivity) and visual acuity. However, most research has used much higher doses of lutein compared with zeaxanthin (60281,91160,97225,106366,108615). Use of near equal amounts, such as zeaxanthin 8-10 mg daily plus lutein 9-10 mg daily for up to 2 years, seems to improve macular density in adults with or without AMD (60175,60268,60270,106358); however, effects on vision when used for up to 2 years in patients with AMD are conflicting (60245,60268,60270,106358). Zeaxanthin has also been evaluated in combination with other ingredients, with conflicting findings. A specific supplement (AZYR SIFI) containing zeaxanthin 1 mg, lutein 10 mg, vitamin C 180 mg, vitamin E 30 mg, zinc 22.5 mg, copper 1 mg, and astaxanthin 4 mg has been used daily for 1-2 years with moderate evidence of benefit (19196,60244). Taking zeaxanthin 2 mg plus lutein 10 mg in addition to the original Age-Related Eye Disease Study (AREDS) formulation (vitamins C and E, beta-carotene, and zinc) does not seem to prevent the progression to advanced AMD more than the AREDS formulation alone. However, this progression was modestly inhibited in individuals with low dietary intakes of lutein and zeaxanthin. While progression to late AMD was only modestly inhibited at 5 years when these doses of lutein and zeaxanthin were included in a revised formulation devoid of beta-carotene (60281), results of an additional 5 years of follow up showed that this revised formulation reduces the risk of progression to late AMD by 15% when compared with the formulation containing beta-carotene (108615). Clinical research shows that adding meso-zeaxanthin 10 mg to this revised AREDS formulation (AREDS2) does not further improve contrast sensitivity in patients with non-advanced AMD (106369). In first-generation offspring of parents with neovascular AMD, taking zeaxanthin 2 mg, lutein 10 mg, vitamin C 180 mg, vitamin E 30 mg, zinc 15 mg, and copper 1 mg daily for 6 months does not improve the macular pigment optical density (106347). Reasons for these discrepancies are not clear but may relate to the patient population, zeaxanthin dose, treatment duration, or other ingredients included in combination products.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral zeaxanthin is beneficial for attenuating cognitive decline in older adults. Details: Clinical research in adults 40-75 years old shows that taking zeaxanthin 2 mg with lutein 10 mg daily for 6 months improves some, but not all, measures of visual memory when compared with placebo. However, other measures of memory and cognitive function were not improved (109763). Also, preliminary clinical research in older adults shows that taking the same dose of zeaxanthin and lutein for one year modestly improves some measures of cognitive function, such as complex attention and cognitive flexibility, when compared with placebo (106367). Some observational research in patients 50 years and older has found that higher dietary lutein and zeaxanthin intake is associated with greater word recall when compared with lower intake (102891). However, clinical research in patients over 60 years old shows that taking zeaxanthin 2 mg with lutein 10 mg daily for 5 years in addition to vitamins C and E, beta-carotene, and zinc (AREDS) does not improve markers of cognitive function, such as memory and verbal fluency, when compared with AREDS alone (94702).
• Alzheimer disease. Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with mild to moderate Alzheimer disease shows that taking zeaxanthin 2 mg, lutein 10 mg, meso-zeaxanthin 10 mg, fish oil 1 gram (providing docosahexaenoic acid 500 mg and eicosapentaenoic acid 150 mg), and vitamin E 15 mg (Memory Health) daily for 12 months does not affect disease severity when compared with placebo. However, there were modest increases in the number of patients experiencing either an improvement or attenuated decline in memory and mood (109764). The effect of zeaxanthin alone is unclear.
• Asthenopia (eye strain). Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Results from one clinical trial show that taking a combination product (Cerebos Pacific Limited) containing zeaxanthin 1 mg, lutein 5 mg, and black currant extract 200 mg daily for 2 weeks modestly improves visual fatigue and eye stress when compared with placebo in patients completing a two-hour visual proof reading task (60214). The effect of zeaxanthin alone on eye strain is unclear.
• Asthma. It is unclear if oral zeaxanthin is beneficial for asthma prevention. Details: Population research has found that a higher dietary intake of zeaxanthin plus lutein is associated with up to 30% lower odds of having asthma when compared with a lower dietary intake (109765). The effects of zeaxanthin intake alone or zeaxanthin supplementation are unclear.
• Breast cancer. It is unclear if oral zeaxanthin is beneficial for breast cancer prevention. Details: Epidemiological research has found that higher serum levels of lutein plus zeaxanthin are associated with a reduced risk of developing breast cancer (10132). The effects of supplemental zeaxanthin are unclear.
• Bronchopulmonary dysplasia. Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that giving preterm and low birth weight infants a specific product (LUTEINofta, SOOFT Italia SpA) containing zeaxanthin 0.0006 mg and lutein 0.14 mg orally once daily, starting at birth and continuing until 36 weeks' corrected gestational age, does not decrease the incidence of bronchopulmonary dysplasia when compared with placebo (91163). The effect of zeaxanthin alone is unclear.
• Cardiovascular disease (CVD). Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in adults 50-85 years old shows that taking lutein 10 mg plus zeaxanthin 2 mg daily for an average of 4.8 years does not decrease the risk of CVD-related mortality or cardiovascular events such as stroke, myocardial infarction, or angina when compared with no supplementation (94701). Individual cardiovascular outcomes were not separately evaluated in this study. The effect of zeaxanthin alone on CVD prevention is unknown.
• Cataracts. Increased levels of zeaxanthin in the blood seems to reduce the odds of developing cataracts. It is unclear if dietary or supplemental zeaxanthin is beneficial for cataract treatment or prevention. Details: Some population research has found that higher blood levels of zeaxanthin are associated with a 30% lower odds of developing age-related cataracts, and more specifically, a 37% decreased risk of developing nuclear cataracts (90944,91161). Population research has also found that higher dietary combined intake of lutein plus zeaxanthin is associated with lower odds of developing cataracts. However, any association between intake of zeaxanthin itself and the development of cataracts is unclear (91162). Clinical research shows that taking zeaxanthin 2 mg and lutein 10 mg daily orally, in addition to the Age-Related Eye Disease Study (AREDS) formulation containing vitamin C 500 mg, vitamin E 400 IU, beta-carotene 15 mg, zinc 80 mg, and copper 2 mg, for an average of 4.7 years decreases the risk of needing cataract surgery by 32% when compared with the AREDS formulation alone in patients with low dietary intake of lutein and zeaxanthin, but not in those with higher dietary intake of lutein and zeaxanthin (94703).
• Child development. It is unclear if oral zeaxanthin is beneficial for child development. Details: Epidemiological research has found that a higher dietary intake of zeaxanthin in the first and second trimesters of pregnancy is associated with increased verbal intelligence and improved behavior in the child at 6-10 years of age. However, the ability to discriminate between a novel or familiar visual stimulus was reduced at about 6 months of age, and there were no effects on most cognitive outcomes in children aged 3-6 years (107106). Other epidemiological research has found that a higher dietary intake of zeaxanthin plus lutein in children aged 3-6 years may be associated with modestly improved executive function at 6-11 years. However, there were no effects on most cognitive outcomes in children aged 3-6 years or 6-11 years (109761).
• Cognitive function. Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in younger adults shows that taking zeaxanthin 2 mg and lutein 10 mg for one year modestly improves some measures of cognitive function, such as spatial memory, when compared with placebo (106348). Observational research has found that intake of choline and lutein plus zeaxanthin is positively associated with cognitive flexibility task performance speed. However, this association is not present with the intake of lutein plus zeaxanthin in the absence of choline (106354). The effect of zeaxanthin alone is unclear.
• Colorectal cancer. It is unclear if oral zeaxanthin is beneficial for colorectal cancer prevention. Details: Although some individual epidemiological research disagrees (3962), most research has found that dietary intake of lutein plus zeaxanthin is not associated with a reduced risk of developing colorectal cancer (34481,106372). However, any association with intake of zeaxanthin alone, as supplements or in the diet, is unclear.
• Diabetes. Observational research suggests that oral zeaxanthin may not be beneficial for the prevention of diabetes or diabetic complications. Details: Some epidemiological research has found that low serum levels of carotenoids, including zeaxanthin and lutein, are associated with impaired glucose tolerance (60161). Other population research has found that increased dietary intake of zeaxanthin plus lutein does not decrease the risk of developing type 2 diabetes (14004,97227). Other epidemiological research in patients with type 2 diabetes has found that an increased serum concentration of zeaxanthin is not associated with reduced cardiovascular mortality over 14 years (109768).
• Esophageal cancer. It is unclear if oral zeaxanthin is beneficial for esophageal cancer prevention. Details: Population research has found that people who consume higher combined amounts of zeaxanthin and lutein in the diet have a 29% lower risk of developing esophageal squamous cell cancer when compared with lower intake (91159). The effects of supplemental zeaxanthin are unclear.
• Fractures. It is unclear if oral zeaxanthin is beneficial for fracture prevention. Details: A meta-analysis of observational research has found that increased dietary intake of zeaxanthin and/or lutein is not associated with a reduced risk of hip fractures (97228). The effects of supplemental zeaxanthin are unclear.
• Gastric cancer. It is unclear if oral zeaxanthin is beneficial for gastric cancer prevention. Details: A meta-analysis of observational research has found that increased dietary intake of lutein and/or zeaxanthin is not associated with a reduced risk of developing gastric cancer (97231). The effects of supplemental zeaxanthin are unclear.
• Glaucoma. Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with open-angle glaucoma shows that taking oral zeaxanthin 2 mg, lutein 10 mg, and meso-zeaxanthin 10 mg daily for 18 months increases macular pigment density, but does not affect visual function, when compared with placebo (109756).
• Hyperlipidemia. Although there has been interest in using oral zeaxanthin for hyperlipidemia, there is insufficient reliable information about the clinical effects of zeaxanthin for this condition.
• Lung cancer. It is unclear if oral zeaxanthin is beneficial for lung cancer prevention. Details: Epidemiological research has found that low serum levels of carotenoids, including zeaxanthin, are associated with an increased risk of lung cancer (12874). However, other epidemiological research has found that higher serum levels of zeaxanthin are not associated with a reduced risk of dying from lung cancer (39690,60160).
• Macular telangiectasia type 2. It is unclear if oral zeaxanthin is beneficial for macular telangiectasia type 2. Details: In patients with macular telangiectasia type 2, observational research has found that taking a specific combination of lutein 10 mg, meso-zeaxanthin 10 mg, and zeaxanthin 2 mg (MacuShield; Alliance Pharmaceuticals) for at least 6 months, with an average duration of 15.7 months, was associated with a stabilization of visual acuity. Also, the number and size of cavitations in the macula were reduced (106355).
• Metabolic syndrome. Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Population research in females shows that the highest dietary intake of zeaxanthin plus lutein is associated with 54% reduced odds of developing metabolic syndrome when compared with the lowest intake. However, when supplements containing zeaxanthin plus lutein were included in the total intake, there was no association with metabolic syndrome (109760).
• Necrotizing enterocolitis (NEC). Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that giving preterm and low birth weight infants a specific product (LUTEINofta, SOOFT Italia SpA) containing zeaxanthin 0.0006 mg and lutein 0.14 mg orally once daily, starting at birth and continuing until 36 weeks' corrected gestational age, does not decrease the incidence of NEC when compared with placebo (91163).
• Non-Hodgkin lymphoma. It is unclear if oral zeaxanthin is beneficial for non-Hodgkin lymphoma prevention. Details: A meta-analysis of observational research has found that increased intake of zeaxanthin/lutein in the diet is associated with an 18% lower risk of developing non-Hodgkin lymphoma when compared with low dietary intake. However, no dose-response relationship was reported (97229). It is unknown if supplemental zeaxanthin has any effect on non-Hodgkin lymphoma risk.
• Pancreatic cancer. It is unclear if oral zeaxanthin is beneficial for pancreatic cancer prevention. Details: A meta-analysis of population research has found that increased dietary intake of zeaxanthin and/or lutein is not associated with a reduced risk of pancreatic cancer (97230). The effects of supplemental zeaxanthin are unclear.
• Parkinson disease. It is unclear if oral zeaxanthin is beneficial for Parkinson disease prevention. Details: Population research has found that people who consume higher amounts of zeaxanthin in the diet do not have a lower risk of developing Parkinson disease (91164). The effects of supplemental zeaxanthin are unclear.
• Pre-eclampsia. It is unclear if oral zeaxanthin is beneficial for the prevention of pre-eclampsia. Details: Some epidemiological research has found that the highest intake of lutein plus zeaxanthin during pregnancy is associated with 68% reduced odds of having pre-eclampsia when compared with the lowest intake (109762). The effects of zeaxanthin supplements are unclear.
• Prostate cancer. It is unclear if oral zeaxanthin is beneficial for prostate cancer prevention. Details: Epidemiological research has found that low serum levels of carotenoids, including zeaxanthin, are not associated with an increased risk of prostate cancer (12874). The effects of supplemental zeaxanthin are unclear.
• Respiratory tract infections. It is unclear if oral zeaxanthin is beneficial for the treatment or prevention of respiratory tract infections. Details: Epidemiological research has found that high serum levels of zeaxanthin are not associated with decreased incidence or severity of respiratory tract infections in the elderly (60152). The effects of supplemental zeaxanthin are unclear.
• Retinopathy of prematurity. Oral zeaxanthin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in preterm and low birth weight infants shows that giving a specific product (LUTEINofta, SOOFT Italia SpA) providing lutein 0.14 mg or 0.5 mg/kg plus zeaxanthin 0.0006 mg or 0.02 mg/kg orally once daily, starting at birth and continuing until 36-40 weeks' corrected gestational age, does not decrease the incidence or severity of retinopathy of prematurity when compared with placebo (60240,60243,91163,102889).
• Ulcerative colitis. It is unclear if oral zeaxanthin is beneficial for ulcerative colitis. Details: In patients in the remission phase of ulcerative colitis, observational research has found that a higher dietary intake of lutein plus zeaxanthin is associated with a reduced incidence of constipation, but not flatulence or feelings of urgency (tenesmus) (106362). The effects of supplemental zeaxanthin are unclear.
• Visual development. It is unclear if taking oral zeaxanthin during pregnancy can improve the visual acuity of the child. Details: Some observational research has found that the highest maternal plasma zeaxanthin levels at delivery are associated with a 38% lower risk of poor visual acuity in children at 3 years of age when compared with the lowest maternal zeaxanthin levels (102888). However, other epidemiological research has found that dietary intake of zeaxanthin plus lutein during the first or third trimesters of pregnancy is not associated with contrast vision or visual acuity in the child at 11-12 years of age (109759). The effects of zeaxanthin supplements are unclear. More evidence is needed to rate zeaxanthin for these uses.

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LIKELY SAFE ...when used in amounts found in foods. Astaxanthin has Generally Recognized as Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when taken orally and appropriately. Astaxanthin 4-18 mg daily has been used with apparent safety for up to 12 weeks. Doses of 40 mg daily have been used with apparent safety for up to 4 weeks (19165,19167,19197,32621,96884,105100).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using in amounts greater than those typically found in foods.

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LIKELY SAFE ...when used orally and appropriately. Consuming up to 20 mg of lutein daily from both dietary and supplemental sources appears to be safe (3219,3220,60167). Lutein supplements have been safely used in clinical trials at doses of up to 20 mg daily for up to 10 years (11798,60133,60177,94703,94701,100986,104570,107107,108615,109763).

CHILDREN: LIKELY SAFE
when used orally and appropriately. A specific product containing lutein (LUTEINofta, SOOFT Italia SpA) has been used with apparent safety in infants at a dose of 0.14 mg daily for 36 weeks (91163).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately in amounts found in foods. The high end of dietary lutein intake ranges from 6.9-11.7 mg/day (3219,3220).

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LIKELY SAFE ...when used orally and appropriately. Riboflavin 400 mg daily has been taken for up to 3 months, and 10 mg daily has been taken safely for up to 6 months (4912,91752,105480). A tolerable upper intake level (UL) has not been established (3094,91752,94089).

CHILDREN: LIKELY SAFE
when used orally and appropriately in dietary amounts. A tolerable upper intake level (UL) has not been established (3094,94089). ...when used orally in higher doses for up to 1 year. Doses of 100-200 mg daily have been used safely for 4-12 months in children ages 9-13 years (71483,105484).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately in dietary amounts. A tolerable upper intake level (UL) has not been established (3094,94089).

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LIKELY SAFE ...when used orally and appropriately in doses of up to 2 mg daily. Zeaxanthin supplements have been safely used in clinical trials at doses of up to 2 mg daily for up to 10 years (94701,94702,94703,108615).

POSSIBLY SAFE ...when used orally and appropriately in amounts greater than 2 mg daily. Zeaxanthin supplements in doses of 8-10 mg daily for up to 12 months have been used with apparent safety in clinical trials (60175,60245).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately. A specific product containing zeaxanthin (LUTEINofta, SOOFT Italia SpA) has been used with apparent safety in infants at a dose of 0.0006 mg daily for 36 weeks (91163). There is insufficient reliable information available about the safety of zeaxanthin at higher doses or in older children.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately in amounts found in foods. Zeaxanthin is found in breast milk and levels correlate with infant status (106365). There is insufficient reliable information available about the safety of supplemental zeaxanthin.

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CYTOCHROME P450 2B6 (CYP2B6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, astaxanthin may decrease levels of drugs metabolized by CYP2B6.  Details In vitro research shows that astaxanthin induces cytochrome CYP2B6 enzyme activity in human hepatocytes (32613). This effect has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, astaxanthin may decrease levels of drugs metabolized by CYP3A4.  Details In vitro research shows that astaxanthin induces CYP3A4 enzyme activity in human hepatocytes (32613). This effect has not been reported in humans.

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TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking riboflavin with tetracycline antibiotics may decrease the potency of these antibiotics.  Details In vitro research suggests that riboflavin may inhibit the potency of tetracycline antibiotics (23372). It is not clear if this effect is clinically significant, as this interaction has not been reported in humans.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking zeaxanthin with antidiabetes drugs might increase the risk of hypoglycemia.  Details In an animal diabetic model, zeaxanthin has hypoglycemic effects (106363). However, population research has found that increasing intake of dietary zeaxanthin plus lutein does not decrease the risk of developing type 2 diabetes (14004,97227).

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General ...Orally, astaxanthin seems to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, red fecal color.

Gastrointestinal ...Orally, astaxanthin 6 mg daily has caused two cases of increased bowel movements and two cases of red fecal color (91736). A higher dose of astaxanthin (AstaCarox, AstaReal AB) 40 mg daily has caused severe stomach/abdominal pain in two patients (19165).

Ocular/Otic ...Canthaxanthin, another carotenoid substance that is chemically related to astaxanthin, has caused crystals in the retina and loss of visual acuity in one patient (8455). This effect has not been observed with astaxanthin, but patients who have visual changes while taking astaxanthin should stop taking it immediately.

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General ...Orally, dietary and supplemental lutein is generally well tolerated. Doses up to 20 mg daily have not resulted in adverse effects.

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General ...Orally, riboflavin is generally well tolerated.
Most Common Adverse Effects:
Orally: Dose-related nausea and urine discoloration.

Gastrointestinal ...Orally, riboflavin has been associated with rare diarrhea and dose-related nausea (1398,71483). In one clinical study, one subject out of 28 reported having diarrhea two weeks after starting riboflavin 400 mg daily (1398).

Genitourinary ...Orally, high doses of riboflavin can cause bright yellow urine. Furthermore, in one clinical study, one subject out of 28 reported polyuria two weeks after starting riboflavin 400 mg daily (1398,3094).

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General ...Orally, dietary and supplemental zeaxanthin are generally well tolerated. No adverse effects have been reported in clinical research.

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