An Ounce Of Prevention Is Worth A Pound Of Cure!

The Soy Renaissance

In addition to its many nutritional benefits, soy may offer relief from common discomforts associated with menopause. Learn more about this super food and how it might help you.

In last week’s newsletter, I touched on the value of dietary soy, especially for women’s wellness. Although the health benefits of soy have been questioned, I believe a negative reputation has been encouraged by lobbyists for the meat and dairy industries. That said, I’m not a “soy nut,” and I do think that traditional diets with meat, dairy or fish protein can be healthy.

Much of the health value of soybeans is actually found in an interesting series of soy components called isoflavones. Isoflavones are a category of natural substances called phytoestrogens (phyto = plant). These plant compounds are believed to have hormone-like effects, but there is more to these potent and versatile natural substances. Phytoestrogens have many biological effects, and they may be best viewed as “adaptogens,” or biological-response modifiers, rather than simple estrogens.

The most abundant and common source of isoflavones are soybeans, which contain the isoflavones genistein, daidzein and glycetein. Phytoestrogens are found in red clover, lignans, fruit or grain fibers and phytosterols. Phytosterols are present in beans, cereals and grass sprouts. Active occurring phytoestrogens are transformed by bacteria in the colon or body enzyme systems into isoflavones or related compounds with estrogen-balancing effects.

Population studies of menopausal women provide convincing evidence that isoflavone-rich soy foods may reduce the occurrence or severity of hot flashes and other discomforts of menopause. Women following traditional soy-enriched diets in Japan have been found to have much higher levels of phytoestrogens in their urine than women in Western societies who follow the Standard American Diet. Along with this finding of high isoflavone intake are reports of significantly less menopausal discomforts, especially a low occurrence of hot flashes, in Japanese women.

The beneficial effects of soy have been attributed to the presence of the isoflavones genistein and daidzein; and these isoflavones have been concentrated and added to many dietary supplements for menopause and PMS management. More than 20 recent clinical trials have tested the ability of soy isoflavones, taken in concentrated forms (pills or soy protein isolates), to reduce hot flashes in menopausal women. While results have been mixed, approximately half of study participants reported improvements in hot flashes in just a few weeks. I believe variations in dosage may account for variations in results.

Soy isoflavones have varying levels of potency in terms of an estrogen-like action. However, they are all weak estrogens or modulators of estrogen’s effects on the body. I have been impressed by the benefits of using isoflavones of different origins together in dietary supplements. With these combinations, additive benefits are seen, and lower dosages of each isoflavone can be used together for greater effects (synergy). In particular, a combination of soy isoflavones and red clover isoflavones may be more effective for hot flashes.

There is a long history of precedent for the safety of soy foods. There are no studies in humans showing significant adverse effects of soy isoflavones, even when taken in relatively large doses (100 mg or more). Reviews of medical and scientific literature suggest that isoflavones in soy may exert significant protective effects in both animals and humans. (See Holt, S., “The Soy Revolution,” Dell Publishing, N.Y., N.Y., 2000). Soy isoflavones are known to function as potent antioxidants and free radical scavengers.

Many women question whether or not plant estrogens (phytoestrogens) cause cancer. Scientists have attempted to address the safety of phytoestrogens in relationship to cancer, but there are many different types of these plant compounds. Certain phytoestrogens have beneficial effects on the body, especially when body estrogen levels are high (independent of actions on estrogen receptors). However, there is no evidence that phytoestrogens used in popular dietary supplements can lead to cancer.

Soy isoflavones appear to be quite safe when used in doses with an existing precedent for safety (up to approximately 80 mg to 100 mg of total soy isoflavones in dietary supplements). While it’s unlikely that anyone would consume more than a total daily intake of 150 mg of isoflavones even if he or she ate a heavily soy-enriched diet, isoflavone supplements are available in a wide range of doses. I would like to stress that continuous use of soy supplements with high doses of soy isoflavones should be avoided.

The complex, beneficial actions of isoflavones and other components of soy make soy foods an extremely valuable dietary addition. For a more complete account of the positive impact of soy on health, please feel free to read my books (“The Soy Revolution,” Dell Publishing, N.Y., 2000; “Soya for Health,” Mary Ann Liebert Publishers, N.Y., 1997; and “Combat Syndrome X, Y and Z”, www.stephenholtmd.com, N.J., 2002).

Be Healthy!
Stephen Holt, MD

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