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Soy - Side Effects
Soy, a staple food in many Asian countries, contains valuable constituents, including protein, isoflavones, saponins, and phytosterols. Soy protein provides essential amino acids. When eaten with rice, soy provides protein comparable with that found in animal products. Soy is low in fat and cholesterol-free.
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Reliable and relatively consistent scientific data showing a substantial health benefit.
Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
This supplement has been used in connection with the following health conditions:
| Used for | Amount | Why |
|---|---|---|
High Cholesterol | 25 grams soy protein per day | Soy supplementation has been shown to lower cholesterol. Soy contains isoflavones, which are believed to be soy’s main cholesterol-lowering ingredients. |
| ||
| Used for | Amount | Why |
|---|---|---|
Hypertension | 10 grams soy protein or 16 ounces soy milk twice per day | Supplementing with soy protein may significantly lower blood pressure. |
| ||
| Used for | Amount | Why |
|---|---|---|
Athletic Performance and Exercise Recovery | 33 to 40 grams daily | In one study, elderly men participating in a strength training program who took a supplement containing protein (part of which was soy protein) immediately following exercise saw significant gains in muscle growth and lean body mass. |
| ||
| Used for | Amount | Why |
|---|---|---|
Obesity | Refer to label instructions | Soy appears to have several effects on the body that might help with weight loss. |
| ||
| Used for | Amount | Why |
|---|---|---|
Premenstrual Syndrome | Refer to label instructions | Supplementing with soy protein may help relieve premenstrual swelling and cramping. |
| ||
Also indexed as:
- soy protein
About this treatment
Side Effects
Soy products and cooked soybeans are safe at a wide range of intakes. However, a small percentage of people have allergies to soybeans and thus should avoid soy products.
Soy isoflavones have been reported to reduce thyroid function in some people. A preliminary trial of soy supplementation among healthy Japanese, found that 30 grams (about one ounce) per day of soybeans for three months, led to a slight reduction in the hormone that stimulates the thyroid gland. Some participants complained of malaise, constipation, sleepiness, and even goiter. These symptoms resolved within a month of discontinuing soy supplements. However, a variety of soy products have been shown to either cause an increase in thyroid function or produce no change in thyroid function. The clinical importance of interactions between soy and thyroid function remains unclear. However, in infants with congenital hypothyroidism, soy formula must not be added, nor removed from the diet, without consultation with a physician, because ingestion of soy may interfere with the absorption of thyroid medication.
Most research, including animal studies, report anticancer effects of soy extracts, though occasional animal studies have reported cancer-enhancing effects. The findings of several recent studies suggest that consuming soy might, under some circumstances, increase the risk of breast cancer. When ovaries have been removed from animals—a situation related to the condition of women who have had a total hysterectomy—dietary genistein has been reported to increase the proliferation of breast cancer cells. When pregnant rats were given genistein injections, their female offspring were reported to be at greater risk of breast cancer. Although premenopausal women have shown decreases in estrogen levels in response to soy, pro-estrogenic effects have also been reported. When pre-menopausal women were given soy isoflavones, an increase in breast secretions resulted—an effect thought to elevate the risk of breast cancer. In yet another trial, healthy breast cells from women previously given soy supplements containing isoflavones showed an increase in proliferation rates—an effect that might also increase the risk of breast cancer.
Of 154 healthy postmenopausal women who received 150 mg of soy isoflavones per day for five years, 3.9% developed an abnormal proliferation of the tissue that lines the uterus (endometrial hyperplasia). In contrast, none of 144 women who received a placebo developed uterine hyperplasia. Although no case of uterine cancer was diagnosed during the study, endometrial hyperplasia is a potential forerunner of uterine cancer. The amount of isoflavones used in this study is two to three times as much as that used in many other studies. Nevertheless, the possibility exists that long-term use of isoflavones could cause uterine hyperplasia, and women taking isoflavones should be monitored appropriately by their doctor.
Some postmenopausal women taking the soy isoflavone genistein have experienced gastrointestinal side effects (abdominal pain, epigastric pain, dyspepsia, vomiting, or constipation).
Last Review: 05-11-2011
Copyright © 2011 Aisle7. All rights reserved. www.Aisle7.net
Learn more about Aisle7, the company.
The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2011.
© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.
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