Soy isoflavones are found in soybeans, which are often made into tofu, soy milk and other food products. Soy isoflavones may offer many important health benefits when you take them in supplements or consume them in your food diet. Before taking soy isoflavones to treat or prevent any disease or medical condition, you should first consult your physician to discuss the proper dosage, risks and interactions.
Benefits
Soy isoflavones might help in treating hypertension, high cholesterol, menopausal symptoms, osteoporosis, premenstrual syndrome (PMS) and vaginitis, according to the University of Michigan Health System. You might also take soy isoflavones to help treat cardiovascular disease and to help prevent certain types of cancer, says the Memorial Sloan-Kettering Cancer Center. Other proposed medicinal uses for soy include treating allergies, cyclic mastitis, osteoarthritis and ulcerative colitis, notes the University of Pittsburgh Medical Center. No widely-accepted medical research supports the use of soy isoflavones for any of these purposes, however.
Function
Soy contains high levels of isoflavones, particularly genistein, daidzein and glycitein, which appear to modulate estrogen receptors selectively. This action is responsible for the suggested use of isoflavones in treating menopausal symptoms, PMS and the several other health conditions. The isoflavone genistein may act to lower blood sugar and insulin levels while boosting insulin resistance, leading to soy isoflavones’ indicated use in treating diabetes. Genistein and daidzein also appear to act in a similar manner as synthetic estrogen to prevent or decrease bone loss relating to osteoporosis. Additionally, soy isoflavones act to inhibit the growth of certain cancer cells. Soy’s other constituents may also contribute to its beneficial effects, but the isoflavones seem to have similar characteristics as estrogen.
Dosage
Although the exact correct dosage of soy isoflavones is unknown, you might take as little as 20 grams of soy protein or as much as 100 mg of soy isoflavones per day, says the University of Michigan Health System. If you want to get the isoflavones from consuming soy in your diet, you could eat 25 grams of soy protein each day, which is equivalent to a half-pound of tofu or two-and-a-half cups of soy milk, according to the University of Pittsburgh Medical Center. Talk with your doctor about the dosage of soy isoflavones that would be safe and effective for the health conditions that you’re interested in treating.
Scientific Evidence
Numerous test tube, animal and human studies or clinical trials have been conducted regarding the beneficial effects of soy isoflavones. For example, a 2000 clinical trial published in the American Journal of Clinical Nutrition found that men with moderately high cholesterol levels experienced cholesterol-lowering effects after consuming only 20 grams of soy protein daily, according to the University of Michigan Health System. A 2002 study involving menopausal women published in the journal Obstetrics & Gynecology found that taking 100 mg of soy isoflavones per day helped to relieve symptoms and also provided cardiovascular benefits over the course of four months, says the Memorial Sloan-Kettering Cancer Center. A study of postmenopausal women published in the American Journal of Clinical Nutrition in 1998 revealed that soy isoflavones slowed down bone-density degradation. Another randomized clinical trial published in the Annals of Internal Medicine in 2007 found that the isoflavone genistein helped to slow bone loss. A preliminary double-blind clinical trial published in the journal Phytomedicine in 2005 indicated that soy isoflavones might help to relieve osteoarthritis symptoms. Another study published in Biomedicine & Pharmacotherapy in 2002 found that soy isoflavones could help to prevent or treat migraine headaches associated with PMS.
Warnings
Because soy is a common food consumed around the world, it’s considered very safe. Some people are allergic to soy, however, so you shouldn’t take any form of soy isoflavone remedies if you have a soy allergy. The soy isoflavone genistein may interfere with tamoxifen’s effects on estrogen-associated breast cancer, warns the Memorial Sloan-Kettering Cancer Center. Soy isoflavones may also affect your thyroid hormone levels, so avoid taking them if you have a thyroid condition. Soy might reduce testosterone levels in men and interfere with the absorption of calcium, iron and zinc, says the University of Pittsburgh Medical Center. If you take supplements of these minerals, try not to consume soy within at least two hours of taking the supplements. Finally, if you take a supplement with the soy isoflavone genistein, you might experience gastrointestinal problems like indigestion, constipation, stomach cramps or vomiting, notes the University of Michigan Health System.
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