William Helferich, a professor of food science and human nutrition at the University of Illinois, reviewed scientific research on breast cancer, soy and soy-containing phytoestrogens at this month’s “Diet and Optimal Health” conference hosted by Oregon State University’s Linus Pauling Institute, according to a May 21 report in Health News Today. Scientific studies on breast cancer, soy and food additives containing soy phytoestrogens were reviewed at the “Diet and Optimal Health” conference sponsored by the Linus Pauling Institute at Oregon State University, noting that whether soy products are healthy food additives, safe alternatives to hormone replacement therapy and carcinogens depends “on the circumstances.” Helferich has been conducting research on the evaluation of the health effects of isoflavones for a decade. Isoflavones are a class of phytoestrogens that are abundant in soybeans. Much of his work has focused on one isoflavone, genistein, which is found in highly variable amounts in soy products such as tofu, soy protein isolate, soy flour and some estrogenic food additives. Genistein is of interest because it is the most active component of soy isoflavones, which activate estrogen receptors in cells that include some breast cancer cells. The results of many studies on the effects of human and phytoestrogens on breast cancer appear contradictory on the surface. Some studies have found that prepubertal feeding of genistein to female rats reduced the number of chemically induced mammary tumors; other studies have shown that estradiol, the main human estrogen, promotes growth in pre-existing estrogen-dependent mammary glands. Helferich and colleagues demonstrated that, like estradiol, dietary genistein stimulates the growth of estrogen-sensitive tumors. They also found that dietary genistein also interfered with the treatment of certain drugs that act on estrogen receptors in breast tumors, such as tamoxifen. Helferich noted that the explanation for this paradoxical result depends on the timing of estrogen administration. Prepubertal administration of the estrogen genistein leads to mammary differentiation and stimulates tumor growth if estrogen is administered to animals that already have estrogen-responsive tumors. In today’s report, Helferich is most concerned about the use of genistein and other isoflavones in food additives that are sold as “natural” alternatives to hormone replacement therapy. He noted that these products are appropriate and safe for middle-aged women to consume, but that women 50 years of age or older are at risk for breast cancer Helferich noted that the incidence of breast cancer in U.S. women 50 years of age and older declined significantly in 2003 and 2003 due to a reduction in the use of hormone replacement therapy. Although purified genistein is not as effective as hormone replacement therapy, it still carries some risk for middle-aged women because of the higher dosage. Many labels of products containing isoflavones of one kind or another lack information about the true ingredients, and because they are natural products, batch-to-batch levels are difficult to control. Helferich says that because genistein is only one component of soy, research on purified genistein alone may lead to misconceptions about the health significance of soy in the diet. In fact, foods like soy flour have been shown to have very different effects, and the complex blend of ingredients in soy flour does not promote tumor growth. Soy contains a variety of biologically active ingredients that together have multiple effects and can reduce the negative effects of a given ingredient. Consuming whole soy foods produces a much different effect compared to taking each concentrated ingredient separately. Helferich says that consuming unprocessed soybeans for less than $1 per serving may be better for your health than spending $30 on food from a health food store. He concludes by noting that all the research boils down to one simple fact: whole soybeans contribute more to health than many of its single chemical components.