In a study published in the British Journal of Cancer, the researchers show that in laboratory tests, a compound called indole-3-carinol (I3C), found in broccoli, cauliflower and cabbage, and a chemical called genistein, found in soy beans, can increase the levels of BRCA1 and BRCA2 proteins that repair damaged DNA.

Although the health benefits of eating your vegetables--especially cruciferous ones, such as broccoli--aren't particularly new, this study is one of the first to provide a molecular explanation as to how eating vegetables could cut a person's risk of developing cancer, an association that some population studies have found, says the study's senior author, Eliot M. Rosen, MD, PhD, professor of oncology, cell biology, and radiation medicine at Georgetown's Lombardi Comprehensive Cancer Center.

"It is now clear that the function of crucial cancer genes can be influenced by compounds in the things we eat," Rosen says. "Our findings suggest a clear molecular process that would explain the connection between diet and cancer prevention."

In this study, Rosen exposed breast and prostate cancer cells to increasing doses of 13C and genistein, and found that these chemicals boosted production of BRCA1, as well as its sister repair protein, BRCA2.

Mutations in either of these genes can lead to development of breast, prostate and ovarian cancers.

Since decreased amounts of the BRCA proteins are seen in cancer cells, higher levels might prevent cancer from developing, Rosen says, adding that the ability of I3C and genistein to increase production of BRCA proteins could explain their protective effects.

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"We believe there is still insufficient evidence to make recommendations for or against the use of low-carbohydrate diets to induce weight loss, especially for durations longer than six months," the authors write. "The differences in weight loss between low-carbohydrate and low-fat diets after 12 months were minor and not clinically relevant."

Because no trials have yet examined the risk of heart attack or death in people on low-carbohydrate diets, it's unclear whether the beneficial effects low-carbohydrate diets appear to have on HDL and triglyceride levels cancel out their apparent negative effects on overall and LDL cholesterol levels, the authors write. "In the absence of evidence that low-carbohydrate diets reduce cardiovascular morbidity and mortality, such diets currently cannot be recommended for prevention of cardiovascular disease," they conclude.

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