Soy: Food More Than Medicine

Many women have pinned hopes on soy as a treatment for menopause-related hot flashes or as a key to reducing risk of breast cancer. Yet, research shows that we may need to shift our expectations of soy and look at it as one healthy food that has lots to offer as part of a plant-based diet.

In menopause, dropping estrogen levels can lead to hot flashes. Soy contains natural compounds that are plant estrogens. These compounds are much weaker than the estrogen our bodies produce, but some researchers and suffering women hoped that their estrogen-like effects might be enough to eliminate hot flashes. However, studies so far show mixed results.

In one study, 99 women ate muffins containing about three servings of unprocessed soy foods daily. After four months, no effect on hot flashes was seen. Another study that looked at soy and other aspects of diet in more than 2,000 women also found no link between soy intake and hot flashes. In this study, higher fiber intake and being less overweight were linked to fewer hot flashes.

Clues in isoflavones?

The Journal of the American Medical Association published an analysis of studies on non-hormonal therapies for hot flashes. Six studies examined an isolated extract in soy called isoflavones, a group of compounds that seems to be the active ingredient in soy.

Previous studies with soy foods had shown inconsistent results and researchers hoped studying the active ingredient might give clearer results, but the impact on hot flashes was again mixed. The authors conclude that overall evidence doesn’t support soy isoflavones reducing hot flashes.

Earlier studies have shown soy foods may help reduce, but usually not eliminate, hot flashes. Women who benefit are mostly those who experience more than five hot flashes daily.

The effectiveness of isoflavones separate from soy foods, as well as the safety of large amounts of isoflavones, is unknown.

The question of breast cancer

Breast cancer has been a primary focus of the research on how soy affects cancer risk. Soy isoflavones act as antioxidants, as well as estrogens. Laboratory research shows soy’s isoflavones may block cancer-promoting effects of estrogen in some tissues.

A 2006 analysis of 18 studies concluded that higher soy consumption could slightly lower risk of breast cancer, but the definition of “high soy” varied among the studies. In some studies, for example, high soy consumption referred to one or more daily servings while in others it referred to daily use.

A 2003 review of 18 different studies concluded that soy has no effect on breast cancer risk, except possibly when consumed during adolescence or eaten in extremely large amounts.

Researchers now say that early exposure to soy foods, which contain isoflavones, may lead to breast cells developing into a form more resistant to cancer-causing influences later in life. Some laboratory research found that soy might increase breast cancer risk in certain cases.

Wonderful meat alternative

Until we have more data on the long-term safety of soy, experts suggest that almost all women can eat up to two or three servings of soy foods a day. Women taking anti-estrogen drugs, such as tamoxifen and aromatase inhibitors, should talk with their doctor about whether or not to consume soy during treatment.

The safety of using large amounts of isoflavones over a long time, in foods or supplements, is relatively scarce and therefore, unwise.

Soy foods are a wonderful meat alternative, with plenty of protein that is low in saturated fat. They also supply fiber, magnesium and selenium.

Instead of looking at soy as medicine, try enjoying it as a healthy food in a balanced diet. Use tofu, tempeh or edamame in stir-fries; munch on edamame or soy nuts for snacks; use tofu in smoothies and soups; and try soymilk to drink, on cereal or in cooking.

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