Soy Milk Estrogen and Menopause: The Light And Dark Sides Of Soy


By John R. Lee, M.D. and Virginia Hopkins

Today, it's all but impossible to find a health-related magazine or TV show that doesn't shout out the benefits of soy foods for the prevention of menopause symptoms, breast and other cancers, heart disease and osteoporosis. In the past decade, the soy industry has poured hundreds of millions of dollars into the research, marketing and advertising of soy foods, and it has been well rewarded for its efforts. However, while we agree that certain soy foods, eaten in moderation, can be a healthy addition to the diet, we believe that women who are eating soy with every meal, or even every day, may be damaging their health. Soy has its good side, but it also has its bad side, which has been largely ignored by those rushing to cash in on this nutritional fad.

Traditional Asian soy foods such as tofu, tempeh, and miso have been a dietary staple in that part of the world for centuries, and they are increasingly found in Western diets. Western food manufacturers have also developed a slew of new soy foods, using these little beige beans as an ingredient in protein powders, hot dogs, burgers, cheese, cereals, sports bars, and other convenience foods. Soy milk, texturized soy protein, and soy cheese have been touted as nutritious alternatives to cow's milk products and meat. Supplement companies create pills from soy phytochemicals and advertise them as natural medicines for relief of menopause symptoms, or as protection against cancer, heart disease, or osteoporosis. Soy powders are sold as supposedly healthy meal alternatives. Some of these products are good for you, and some are best avoided. In this chapter you'll find out how to eat soy foods so they enhance your health….



With all that we know about the pitfalls of conventional medicine's treatment of women in menopause, it makes sense that women are turning to natural approaches to relieve menopausal discomforts. The beneficial effects of estrogen on these discomforts are indisputable, but as women become more informed they see that the risks – especially of breast cancer – may be too great to justify its use. Others stop using conventional HRT because of side effects, and look to natural remedies to help them control their menopause symptoms.

This growing interest in natural solutions for treating menopausal symptoms has prompted the food and supplement industries to develop alternatives to conventional pharmaceutical estrogens such as Premarin. The soy foods industry has been poised to benefit most from this search for natural remedies for menopause because of soy's high phytoestrogen content.

The lay press and the soy industry have widely promoted the message that soy phytoestrogens act, in effect, as surrogate estrogens. Such a message gives women the impression that they can use soy to naturally relieve symptoms of falling estrogen levels at menopause. While the research does show that isoflavones behave like estrogens in the body the conclusion that they are all the medicine a woman needs to help her through menopause is not borne out by recent clinical studies on soy and menopausal symptoms.

Soy phytoestrogens have very little effect on vasomotor symptoms such as hot flashes, night sweats and vaginal dryness. In one comprehensive study from the Bowman Gray School of Medicine in North Carolina, researchers looked at the effects of soy phytoestrogens on women aged 45 to 55 with menopausal symptoms. This study was big news because the women who took a phytoestrogen-rich soy supplement reported a 50 percent decrease in the severity of their hot flashes. What most news stories didn't mention, however, is that the placebo group reported a 35 percent reduction. Furthermore, this study showed small reductions in the severity of hot flashes, but none on their frequency. In other words, these women were having just as many hot flashes as they did before they added soy foods or supplements, but the intensity of those hot flashes were diminished. While decreased intensity is certainly a good thing when it comes to hot flashes, soy estrogens are clearly not as potent as many forms of conventional estrogen replacement which often eliminate hot flashes quickly and completely.

A recent study of women with vasomotor symptoms at the Mayo Clinic showed no benefits from soy protein isolates, which have high levels of phytoestrogens. This has also been Dr. Zava's experience in analyzing saliva hormone level results accompanied by detailed questionnaires; soy phytoestrogens simply don't work well to control vasomotor symptoms. The isoflavones in soy are aromatase inhibitors which lower the levels of estrogens made by the body, which is counter-productive to controlling vasomotor symptoms.

Soy phytoestrogens do have the estrogenic effect of stimulating the growth of breast cancer cells in tissue cultures. Several studies presented at a recent soy symposium showed that soy protein isolates stimulate the growth of normal breast cells much the way that natural estrogens do, and of course this would add to breast cancer risk if progesterone is not present.

To read more about how to eat soy so that it helps not hurts, please read Dr. Lee's book, What Your Doctor May Not Tell You About Breast Cancer