| Ingredients | Amount Per Serving |
|---|---|
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Calories
|
5 Calorie(s) |
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Calories from Fat
|
5 Calorie(s) |
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Trans Fat
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0.5 Gram(s) |
| 500 mg | |
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Approximate Fatty Acid Content
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|
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(LA)
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365 mg |
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(18:3n-6, GLA)
|
45 mg |
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(standardized to contain 40% Isoflavones)
|
50 mg |
Gelatin, Vegetable Glycerine, yellow Beeswax, Soy Lecithin, natural Caramel color
Below is general information about the effectiveness of the known ingredients contained in the product Evening Primrose Oil 500 mg with Soy Isoflavones. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
Below is general information about the safety of the known ingredients contained in the product Evening Primrose Oil 500 mg with Soy Isoflavones. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
LIKELY SAFE ...when used orally in amounts found in foods. CLA occurs naturally in milk fat, beef, and the meat of other ruminant animals (5924,5925,5932,5933).
POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts of up to 6. 8 grams daily, short-term (2819,2821,3153,4947,10410,11327,111056).
CHILDREN: LIKELY SAFE
when used orally in amounts found in foods.
CLA occurs naturally in milk fat, beef, and the meat of other ruminant animals (5924,5925,5932,5933).
CHILDREN: POSSIBLY SAFE
when used orally and appropriately in medicinal amounts.
Some evidence suggests that CLA 3 grams daily can be taken safely for up to 7 months (45713).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts found in foods (5924,5932,5933).
There is insufficient reliable information available about the safety of CLA when used in medicinal amounts during pregnancy or lactation; avoid using.
LIKELY SAFE ...when used orally and appropriately. Evening primrose oil has been used safely in doses up to 6 grams daily for up to 1 year (7566,7567,8926,12036,20512,49286,49360,109426). There is insufficient reliable information available about the safety of evening primrose oil when used topically. There is also insufficient reliable information available about the safety of evening primrose seed, flower, or leaf when used orally or topically.
CHILDREN: POSSIBLY SAFE
when evening primrose oil is used orally and appropriately, short-term.
In children up to 5 years of age, doses of evening primrose oil up to 3 grams daily have been used safely for 5 months (20512,49273), and 0.5 grams/kg daily has been used safely for 8 weeks (7570). In children up to 12 years of age, doses of 4-6 grams daily have been used safely for 3-5 months (7565,7566,20512,49286). ...when used topically and appropriately, short-term. In children 2-10 years of age, evening primrose oil has been applied to affected areas of the skin twice daily for up to 3 months (96718). There is insufficient reliable information available about the safety of evening primrose seed, flower, or leaf when used orally or topically.
PREGNANCY: POSSIBLY SAFE
when evening primrose oil is used orally and appropriately.
In small studies of evening primrose oil for pre-eclampsia, 4 grams has been used orally daily for up to 10 weeks during pregnancy with apparent safety (1409,20525). Evening primrose oil has also been used safely during the last week of pregnancy to improve cervical ripening (20524,96717), although in one retrospective case series improvement was lacking and there was a trend toward prolonged labor, increased rates of arrest of descent, and increased oxytocin requirements (1411). Evening primrose oil has also been linked to a case report of petechiae and ecchymoses in a newborn infant whose mother took a total of 6.5 grams during the week before giving birth (16303); use with caution, especially in high doses.
LACTATION: POSSIBLY SAFE
when evening primrose oil is used orally.
Supplementation with evening primrose oil during lactation results in the secretion of high levels of the constituent gamma linolenic acid into breast milk (1982); however, this fatty acid is normally present in significant amounts in breast milk (11884).
LIKELY SAFE ...when soy protein is used orally and appropriately. Soy protein products in doses up to 60 grams, providing up to 185 mg isoflavones, daily have been safely used in studies lasting up to 16 weeks (842,2293,2294,2296,3025,3402,3977,4755,6412,8530)(10372,11805).
POSSIBLY SAFE ...when soy extracts are used orally and appropriately, short-term. Soy extracts containing concentrated isoflavones in doses of 35-120 mg daily have been used with apparent safety for up to 6 months (4751,6455,7802,12040,12048,13209,95994,95999).
CHILDREN: LIKELY SAFE
when consumed in amounts commonly found in foods or as a component of infant formula (3400,4912,7331).
Soy milk that's not designed for infants should not be used as a substitute for infant formula. Regular soy milk can lead to nutrient deficiencies (12045). Most evidence shows that exposure to soy formula or other soy products in infancy does not cause early onset of puberty or health or reproductive problems later in life (7331,11080,108245). However, some small cohort studies have suggested that higher soy intake during childhood may be associated with an increased risk of precocious puberty (108240) and may be weakly correlated with the development of breasts in children less than 2 years of age (75520). This is in contrast to an observational study in Chinese children ages 7-9 years which suggests that higher soy intake is associated with delayed puberty (108252). One small cohort study has also found that use of soy infant formula may be associated with an increased risk of endometriosis in adulthood, although endometriosis was also correlated with prematurity, which may have confounded the findings (101803).
CHILDREN: POSSIBLY UNSAFE
when used orally as an alternative to cow's milk in children with severe milk allergy (75359).
Although soy protein-based infant formulas are often promoted for children with milk allergy, children with a severe allergy to cow's milk are also frequently sensitive to soy protein (9883). There is insufficient reliable information available about the safety of soy products when used in amounts higher than typical food quantities for children.
PREGNANCY: LIKELY SAFE
when used orally in amounts commonly found in foods (4912).
PREGNANCY: POSSIBLY UNSAFE
when used orally in medicinal amounts.
Soy contains mildly estrogenic constituents (3373,3988,3989,3990,3994,6029,75303). Theoretically, therapeutic use of soy might adversely affect fetal development; avoid using.
LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods (4912).
A single 20-gram dose of roasted soybeans, containing 37 mg isoflavones, produces four to six times less isoflavones in breast milk than provided in a soy-based infant formula (2290). There is insufficient reliable information available about the safety of long-term use of therapeutic amounts of soy during lactation.
Below is general information about the interactions of the known ingredients contained in the product Evening Primrose Oil 500 mg with Soy Isoflavones. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
Theoretically, CLA may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
 Details
Some clinical evidence suggests that intake of CLA reduces platelet aggregation by approximately 10% (45607). The clinical significance of this effect is unclear.
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Theoretically, taking CLA with antihypertensive drugs might increase the risk of hypotension.
Details
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Theoretically, taking black seed with ramipril might increase the risk of hypotension.
Details
Some clinical research shows that CLA enhances the blood pressure-lowering effects of ramipril (45569).
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Theoretically, evening primrose oil may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Details
Evening primrose oil contains gamma linolenic acid (GLA). There is preliminary clinical evidence that GLA can reduce platelet aggregation and prolong bleeding time (1979).
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Theoretically, evening primrose may increase the levels and clinical effects of CYP2C9 substrates.
Details
In vitro research shows that linoleic acid, a constituent of evening primrose oil, inhibits CYP2C9 (21017).
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Theoretically, concomitant use of lithium with evening primrose oil might decrease lithium levels and effects.
Details
In a case report, a patient on a stable dose of lithium for 10 years experienced a reduction in lithium levels after taking evening primrose oil 500 mg daily. Baseline levels were 0.69 mmol/L, which decreased to 0.37 mmol/L after 2 months and 0.23 mmol/L after 3 months of use. Lithium levels increased within 6 weeks of discontinuing evening primrose oil, to 0.73 mmol/L; no clinical effects were noted (96715).
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Theoretically, evening primrose oil might increase the levels and effects of lopinavir.
Details
In a case report, an HIV patient who took evening primrose oil (Efamol) along with lopinavir/ritonavir experienced an increase in serum levels of lopinavir to 15.2 mg/L. Six weeks after discontinuing evening primrose oil, levels of lopinavir returned to the normal range of 5-10 mg/L. When re-challenged with evening primrose oil for a week, the patient's lopinavir levels increased from 6.69 to 8.11 mg/L. It is suspected that evening primrose oil increases levels of lopinavir by inhibiting cytochrome P450 3A4 (CYP3A4), which metabolizes lopinavir (93578). However, this effect has not been reported in other research.
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Theoretically, taking evening primrose oil with phenothiazines might increase the risk of convulsions.
Details
Evening primrose oil contains gamma-linolenic acid (GLA). There is some concern that taking supplements containing GLA might cause seizures, or lower the seizure threshold, when taken with phenothiazines (88187). In one report, three patients with schizophrenia who had received phenothiazines developed EEG changes suggestive of temporal lobe epilepsy after starting treatment with GLA, although none experienced an actual seizure (21013). In another report, two patients with schizophrenia who were stabilized on phenothiazines developed seizures when evening primrose oil 4 grams daily was added. One of these patients had a prior history of seizures (21010). It is unclear whether evening primrose oil had any additive epileptogenic effects with the phenothiazines; there is no evidence that taking evening primrose oil alone causes seizures (88187).
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Theoretically, GLA might increase the risk of bleeding when taken with anticoagulant or antiplatelet rugs.
Details
Animal and human research suggests that GLA reduces platelet aggregation (1979).
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Theoretically, antibiotics may decrease the activity of soy isoflavones.
Details
Intestinal bacteria are responsible in part for converting soy isoflavones into their active forms. Antibiotics may decrease the amount of intestinal bacteria and decrease its ability to convert isoflavones (7657).
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Soy can lower blood glucose and have additive effects with antidiabetes drugs.
Details
Clinical research shows that whole soy diets and soy-based meals reduce fasting glucose levels in diabetic and non-diabetic individuals (75268,75296,75378,75493,96001). Also, individuals following a soy-based meal replacement plan seem to require lower doses of sulfonylureas and metformin to manage blood glucose levels when compared with individuals following a diet plan recommended by the American Diabetes Association (75268).
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Theoretically soy protein may have additive effects with antihypertensive drugs and increase the risk of hypotension.
Details
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Theoretically, soy might reduce the clearance of caffeine.
Details
Soy contains genistein. Taking genistein 1 gram daily for 14 days seems to inhibit caffeine clearance and metabolism in healthy females (23582). This effect has been attributed to inhibition of the cytochrome P450 1A2 (CYP1A2) enzyme, which is involved in caffeine metabolism. It is unclear if this effect occurs with the lower amounts of genistein found in soy.
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Soy might modestly induce CYP2C9 enzymes. However, this effect does not seem to be clinically significant.
Details
In vitro research suggests that an unhydrolyzed soy extract might induce CYP2C9. However, the significance of this interaction is likely minimal. In healthy females taking a specific extract of soy (Genistein Soy Complex, Source Naturals), blood levels of losartan, a CYP2C9 substrate, were not significantly affected (16825).
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Theoretically, soy might have additive effects when used with diuretic drugs.
Details
Animal research suggests that genistein, a soy isoflavone, increases diuresis within 6 hours of subcutaneous administration in rats. The effects seem to be similar to those of furosemide (75604). This effect has not been reported in humans.
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Theoretically, soy might competitively inhibit the effects of estrogen replacement therapy.
Details
Soy contains phytoestrogens and has been shown to have estrogenic activity in some patients (3860). Although this has not been demonstrated in humans, theoretically, concomitant use of soy with estrogen replacement therapy might reduce the effects of the estrogen replacement therapy.
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Soy products might reduce the absorption of levothyroxine in some patients.
Details
Preliminary clinical research and a case report suggest that soy-based formulas inhibit the absorption of levothyroxine in infants with congenital hypothyroidism (20636,20637,75548,90959). A levothyroxine dosage increase may be needed for infants with congenital hypothyroidism while using soy-based formulas, and the dose may need to be reduced when soy-based formulas are no longer administered. However, in postmenopausal adults, clinical research shows that taking a single dose of soy extract containing isoflavones 60 mg along with levothyroxine does not affect the oral bioavailability of levothyroxine (95996).
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Taking soy products containing high amounts of tyramine along with MAOIs can increase the risk of hypertensive crisis.
Details
Fermented soy products such as tofu and soy sauce contain tyramine, a naturally occurring chemical that affects blood pressure regulation. The metabolism of tyramine is decreased by MAOIs. Consuming more than 6 mg of tyramine while taking an MAOI can increase the risk of hypertensive crisis (15649). The amount of tyramine in fermented soy products is usually less than 0.6 mg per serving; however, there can be significant variation depending on the specific product used, storage conditions, and length of storage. Storing one brand of tofu for a week can increase tyramine content from 0.23 mg to 4.8 mg per serving (15649,15701,15702). Advise patients taking MAOIs to avoid fermented soy products that contain high amounts of tyramine.
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Theoretically, combining soy isoflavones with transdermal progesterone may worsen bone density.
Details
Clinical research suggests that significant bone loss may occur in females with osteoporosis who receive a combination of transdermal progesterone with soy milk containing isoflavones when compared with placebo, soy milk alone, or progesterone alone (69859).
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Theoretically, estrogenic soy isoflavones might alter the effects of tamoxifen.
Details
Laboratory research suggests that genistein and daidzen, isoflavones from soy, can antagonize the antitumor effects of tamoxifen under some circumstances (7072,14362,8966); however, soy isoflavones might have different effects when used at different doses. A relatively low in vitro concentration of soy isoflavones such as 1 microM/L seems to interfere with tamoxifen, whereas high in vitro concentrations such as those >10 microM/L might actually enhance tamoxifen effects. People on a high-soy diet have soy isoflavones levels ranging from 0.1-6 microM/L. Until more is known, advise patients taking tamoxifen to avoid therapeutic use of soy products.
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Theoretically, soy might interfere with the effects of warfarin.
Details
Soy milk has been reported to decrease the international normalized ratio (INR) in a patient taking warfarin. The mechanism of this interaction is not known (9672). However, animal and in vitro research suggests that soy may also inhibit platelet aggregation (3992). Dosing adjustments for warfarin may be necessary.
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Below is general information about the adverse effects of the known ingredients contained in the product Evening Primrose Oil 500 mg with Soy Isoflavones. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
General
...Orally, CLA is well tolerated when found in foods.
When taken in medicinal amounts, CLA seems to be well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea, dyspepsia, flatulence, loose stools, and nausea.
Serious Adverse Effects (Rare) :
Orally: Cases of hepatotoxicity have been reported.
Cardiovascular
...Some preliminary clinical research suggests that the t10,c12 isomer of CLA can decrease high-density lipoprotein (HDL) cholesterol levels (2821).
This isomer of CLA, as well as a mixture of CLA isomers, seems to increase plasma triglyceride levels, the ratio of low-density lipoprotein (LDL) cholesterol to HDL cholesterol, and the ratio of total cholesterol to HDL cholesterol (45148,45468), although not all research has identified these effects (107475).
A meta-analysis of 6 randomized, controlled trials shows that administration of CLA in individuals who are overweight or obese significantly increases lipoprotein (a) levels, a value associated with increased risk of cardiovascular disease. Subgroup analyses suggest this increase is more prominent in trials that are longer than 6 months in duration and with CLA doses of at least 3.5 grams daily (107475).
Endocrine ...Orally, CLA has been shown to increase insulin resistance and glucose concentrations, as well as decrease insulin sensitivity in some patients, including obese individuals or patients with type 2 diabetes (2821,13026,45145,45152,45513). Some evidence suggests that this effect is isomer-specific and occurs with only the t10,c12 isomer (2821,13026), while other evidence shows that decreased insulin sensitivity may also occur with the c9,t11 isomer or with a 50:50 mixture of c9,t11 and t10,c12 isomers (45145,45152).
Gastrointestinal ...Orally, the most common adverse effect reported with CLA is gastrointestinal upset including diarrhea, constipation, nausea, loose stools, dyspepsia, bloating, and flatulence (3153,4947,45280,45705,45730,111056). Esophageal irritation was reported in one patient who bit open and swallowed a capsule containing CLA (45577).
Hepatic ...Orally, clinical research shows that CLA 3 grams daily for 12 weeks does not affect liver outcome measures (105809). However, there are at least two case reports of hepatotoxicity. Asthenia, jaundice, and pruritus were reported in a 46-year-old female who consumed CLA for two weeks. Abnormal liver enzyme levels returned to normal following discontinuation of CLA supplementation (45483). Hepatotoxicity, presenting as fulminant hepatitis and characterized by anorexia, nausea, jaundice, choluria, and hepatic encephalopathy requiring liver transplantation has also been reported in a 63-year-old female taking a CLA-containing weight-loss supplement for one month (91589).
Musculoskeletal ...Orally, CLA has been reported to cause back ache in one individual in one clinical trial (45787).
Neurologic/CNS ...Orally, CLA may cause headache or fatigue (3153,45787). In one case report, a 50-year-old female presented with headache and subarachnoid hemorrhage due to reversible cerebral vasoconstriction syndrome (RCVS) after taking a combination product containing green tea, L-carnitine, and CLA for one week. At 28 days after discontinuation of the combination product and surgery, angiography showed complete regression of vascular restrictions (97007). It is unclear if this adverse effect was due to CLA, another ingredient in the product, or a combination of ingredients.
Other ...Orally, CLA has been reported to cause halitosis in one patient in one clinical trial (45839).
General
...Orally and topically, evening primrose oil is generally well tolerated.
There is limited reliable information available regarding the safety or adverse effects of other parts of the plant.
Most Common Adverse Effects:
Orally: Abdominal pain and distention, diarrhea, dyspepsia, flatulence, nausea, and vomiting.
Dermatologic ...Orally, use of evening primrose oil has been associated with reports of skin rash and acne (9156,9794,49338). There is a case report of extensive but transient petechiae and purpuric ecchymoses in a newborn infant whose mother had consumed raspberry leaf tea and a total of 6.5 grams of evening primrose oil orally and vaginally during the week prior to delivery. The infant had a normal platelet count and no signs of hemorrhage, and was discharged healthy at 3 days of age (16303).
Gastrointestinal ...Gastrointestinal complaints, including abdominal pain, distension and fullness, nausea and vomiting, diarrhea, dyspepsia, and flatulence are the most common adverse effects of evening primrose (8926,9794,20533,49188,49286,49339,49365,65864,88184,102556). Often these effects resolve with continued use. Altered taste has also been reported (49339).
Hematologic ...There is preliminary clinical evidence that evening primrose oil can decrease platelet aggregation and prolong bleeding time. In a small study of patients with hyperlipidemia, taking evening primrose oil 3 grams daily for 4 months was associated with a 40% increase in bleeding time, and decreases in ADP- and epinephrine-induced platelet aggregation of 50% and 60% respectively (1979). There is also a case report of diffuse ecchymoses and petechiae in a neonate whose mother had consumed 6.5 grams of evening primrose oil over the week prior to delivery (16303).
Neurologic/CNS
...Cases of dizziness (9794) and headache (88184) have been reported with evening primrose oil when used orally.
There is a report of seizures in a patient taking evening primrose oil and receiving anesthesia; however, the patient was also taking other drugs and it is therefore unclear if evening primrose was the cause (613). There is also concern that evening primrose oil might cause seizures, or lower the seizure threshold, in patients with schizophrenia who are treated with phenothiazines. This is based on limited data from two studies published in the 1980s. In one report, three patients with schizophrenia who had received phenothiazines developed EEG changes suggestive of temporal lobe epilepsy after starting treatment with evening primrose, although none experienced an actual seizure (21013). In the other report, two patients with schizophrenia who were stabilized on phenothiazines developed seizures when evening primrose oil 4 grams daily was added. One of these patients had a prior history of seizures (21010). There is no evidence that evening primrose taken alone, without medications known to lower the seizure threshold, can cause seizures (88187).
Other ...Weight gain has been reported in individuals receiving evening primrose oil (49338).
General
...Orally, GLA seems to be well tolerated.
Most Common Adverse Effects:
Orally: Mild gastrointestinal adverse effects, including belching, bloating, diarrhea, dyspepsia, flatulence, nausea, and vomiting.
Gastrointestinal ...Orally, GLA may cause mild gastrointestinal effects such as dyspepsia, nausea, bloating, vomiting, soft stools, diarrhea, flatulence, and belching (7701,7702,8926,107927).
Hematologic ...Orally, GLA might prolong bleeding time (1979).
General
...Orally, soy is well tolerated.
Most Common Adverse Effects:
Orally: Bloating, constipation, diarrhea, and nausea.
All ROAs: Allergic reactions.
Endocrine
...In the 1950s and 1960s, cases of altered thyroid function, particularly goiter, were reported in children taking soy formula.
However, adding iodine to soy formula or replacing soy flour in formula with soy protein isolate has nearly eliminated the risk of altered thyroid function in most infants (75353,75651).
In adults, there is some evidence that soy intake can alter thyroid function. Results from one clinical trial suggests that consuming soybeans 30 grams daily for as little as one month can increase thyroid-stimulating hormone (TSH) and decrease thyroxine, causing diffuse goiters, constipation, fatigue, and lethargy in some Japanese men. Recovery was achieved by discontinuing soybean intake (75206,75353). There is also some evidence that soy inhibits thyroid hormone synthesis resulting in increased secretion of TSH in some postmenopausal patients (7806). However, this seems to only occur in people with iodine deficiency (6466,75311). In postmenopausal patients with normal levels of iodine, taking a soy extract for 6 months does not seem to significantly affect thyroid hormone levels (13010).
Evidence from a single case-control study suggests that consumption of soy-based formulas may be associated with an observed three-fold increase in the risk of breast development in Puerto Rican children less than 2 years-old (75520). The correlation has been attributed to the estrogenic activity of soy. However, other risk factors, including a maternal history of ovarian cysts and consumption of meat products were also associated with the increased risk of breast development prior to 2 years of age. Also, the investigators noted that in over half of the cases, the child had not been exposed to soy or any of the other risk factors. Therefore, factors other than soy consumption may be more strongly associated with the increased risk of breast development prior to 2 years of age.
Gastrointestinal ...Gastrointestinal upset, such as constipation, diarrhea, bloating, and nausea are the most common side effects of soy (2297,11033,11082,15851,75491,95999). Reports of "bad taste" and taste intolerance have also been documented in clinical research (15851,39007,75491). Firmer stools, diarrhea, colitis, and intestinal mucosal damage has been reported in infants fed soy protein formula (75161,75448,75516,75525).
Genitourinary
...Orally, soy might increase discomfort during menstrual periods.
Evidence from a small, retrospective cohort study has found that consuming soy formula as an infant may slightly increase the duration and discomfort of menstrual periods later in life. However, the investigators noted that these differences may not be clinically significant (7331).
Orally, frequent soy consumption might be a risk factor for uterine leiomyoma, an estrogen-dependent benign tumor located on the uterus. Observational research found that consumption of soy milk or soybean at least four times weekly is associated with a 7-fold increased odds of uterine leiomyoma (98869).
There is some concern that use of soy-based formulas in infants might result in long-term health complications. However, results from a retrospective cohort study has found that intake of soy-based formula as an infant does not affect height, weight, body mass index, pubertal maturation, menstrual history, or pregnancy history, nor does it increase the risk of reproductive organ disorders, hormonal disorders, libido dysfunction, or birth defects in the offspring of adults who received soy formula as infants (7331,11080). Additionally, research in adults shows that urinary phytoestrogens are not associated with endometriosis risk (101804). However, some population research has found that regular exposure to soy-based formulas during infancy is associated with an increased risk for endometriosis (101803).
Immunologic
...Orally, soy can cause allergic reactions such as skin rash and itching in some people (6412).
In an 11-year-old female, allergy to soy protein resulting in a delayed itching papular rash was thought to be responsible for the reaction to injected benzathine benzylpenicillin containing possible soy protein-contaminated soy lecithin (96422).
Topically, soy-based ingredients were responsible for the development of hand atopic dermatitis in a young female using cosmetic lotions in the workplace. Percutaneous sensitization resulted in the development of anaphylaxis to oral soy (96000).
Neurologic/CNS ...Orally, one clinical study showed that insomnia was more common in postmenopausal adults taking soy isoflavone supplements when compared with those receiving placebo (9917). Some research suggests that dietary consumption of tofu during midlife might decrease cognitive function in later years. Evidence from one retrospective cohort study suggests that males who consume at least two servings of tofu weekly during midlife have increased risk of cognitive impairment in late life (19% vs. 4%) compared to those who consume tofu less frequently. Although the effect of tofu was considered to be marginal compared to other factors such as age, education, or history of stroke, results from the study suggest that the effect of significant midlife consumption of tofu is comparable to the effect of an age difference of 4 years or an education difference of 3 years. However, numerous other factors, such as lifestyle and health, could be involved (6415,6416). Therefore, these findings are too preliminary to be used as a basis for clinical recommendations.
Oncologic
...There is controversy about the role of soy in breast cancer.
Population studies suggest that soy is protective against breast cancer. Asian females who eat a traditional diet high in soy seem to have a lower risk of developing breast cancer (4590,5939,9674). Early exploratory studies have suggested that soy stimulates proliferation of normal human breast tissue (3980,3981). However, taking a soy tablet containing 50 mg soy isoflavones daily for 12 months does not alter mammographic or breast MRI tissue density in adults at high risk of breast cancer, with non-endocrine treated breast cancer, or previously treated for breast cancer and without evidence of recurrence (95999).
There is some concern that soy supplements, but not soy foods, might increase the risk of endometrial hyperplasia due to its estrogenic effects. Population and clinical research suggests that soy foods do not have a proliferative effect on endometrial cells (7358,2429,7654,9676,9917), and increased dietary soy and phytoestrogens are associated with reduced endometrial cancer risk (7338,10372). However, the effects seem to be different with concentrated soy isoflavone extract. While taking products providing isoflavones 120 mg daily for 6 months does not increase endometrial thickening (13209), taking higher doses such as isoflavones 150 mg daily for 5 years might increase the risk of simple endometrial hyperplasia (12105). However, there is no evidence that soy isoflavones increase the risk of atypical hyperplasia which has a much higher risk of developing into endometrial cancer than simple endometrial hyperplasia (12105,90973).
There is also concern that increased soy intake increases the risk for other types of cancer. Some observational research has found that higher dietary intake of soy is associated with a higher risk for bladder cancer and pancreatic cancer (9677,105609).
A meta-analysis of results from cohort and case-control studies evaluating the risk of stomach cancer related to consumption of fermented soy products is unclear and inconclusive. The highest quality data from cohort studies suggests that these products have no significant effect on stomach cancer (7340,7341). More research is required to determine if soy products have any correlation with stomach cancer.
Pulmonary/Respiratory ...Inhaled soy dust and soy hull aeroallergen can trigger symptoms of asthma and allergic rhinitis (5084,5085,5086).
