Is Soy a Cancer Fighter or Enabler?

We’ve all hear the adage, “You are what you eat,” but when it comes to soy, is that good or bad?

The true role soy foods play in cancer prevention or triggering malignant cell growth is difficult to discern from current research studies. The bottom line is no one knows for certain.

The confusion over soy is pervasive among women. A recent study of women in a cancer risk assessment program showed that 45 percent of women who ate soy on a regular basis did so to lower their cancer risk. Yet 7 percent of women in the same study said they avoided soy foods because it might increase their risk of breast cancer.

Many studies over the last 15 years have shown soy to be beneficial in lowering the risk for some types of cancers. For instance, Asian women who consume high amounts of soy during their lifetimes have lower risk of breast cancer. The caveat is that these same women also eat less fat and their diets high are in fiber, so soy’s role in reducing their cancer risk is likely just one part of the equation.

Soy beans have been called a “Superfood” because it has been found in laboratory studies to lower the risk or effects of everything from menopause, prostate cancer cell growth, COPD in smokers’ lungs, to weight loss and diarrhea in infants. However, some experts say soybeans can mimic hormones in the body. A high level of estrogens, the main female hormone, has been linked to increased breast cancer risk.

The lab studies analyzing soy’s estrogen-like phytochemicals, called isoflavones, have been all over the map. Soy’s isoflavones can bind to estrogen receptors. This activity can possibly block estrogen’s breast cancer-promoting effects naturally by lowering estrogen in the body. But in theory, in women with breast cancer or a history of breast cancer, isoflavones may actually act as weak estrogens, increasing the risk of the cancer growing or coming back.

A new study published in June 2009 Nutrition Journal concluded that soy isoflavones’ estrogen-like effects are probably too weak to have any significant consequence on breast tissue in healthy women — or possibly breast cancer survivors.

While the jury is clearly still out on soy, many women seek guidelines for soy food consumption. The following is a synopsis of the current state of the evidence:

• Soy consumed at normal (moderate) dietary levels — one or two servings daily (eight ounces of soymilk, four ounces of tofu or tempeh, or a half-cup of edamame, up to 100 milligrams of isoflavones) — is probably safe for most women.
• As a precaution, women receiving anti-estrogen treatments should minimize soy foods and avoid isoflavone supplements. Talk to your doctor.
• Evidence does not support adding soy to your diet hoping that it will help prevent breast cancer. Do note, however, that soy is still considered a healthful choice. It is low in saturated fat, high in nutrients, fiber and antioxidant phytochemicals.

Azsunshinegirl, aka Lynette Summerill, is an award-winning journalist who lives in Scottsdale, Arizona. In addition to writing about cancer-related issues, she writes a blog, Nonsmoking Nation, which follows global tobacco news and events.