Evidence now suggests eating soy foods in puberty protects against bre...( Washington D.C. Evidence is growing...)

Washington, D.C. Evidence is growing from animal and human studies that genistein, a potent chemical found in soy, protects against development of breast cancer - but only if consumed during puberty, says a Georgetown University Medical Center researcher in the British Journal of Cancer published online today. The challenge now, she says, is for scientists to understand precisely why soy appears to provide a shield against the most common cancer in women.

Timing seems to be vitally important in use of this bioactive food, and if we can figure out why that is so, then we may be able to help prevent breast cancer in the widest sense possible, says the researcher, Leena Hilakivi-Clarke, Ph.D., a professor of oncology at the Lombardi Comprehensive Cancer Center at Georgetown.

Although there are a number of tantalizing theories to explain the connection, at the present time no convincing explanation can be offered as to why the breast cancer-risk reducing effect of genistein might be strongest during childhood and early adolescence, she says.

Hilakivi-Clarke is a senior author of a review article published in the journal that sums up the state of knowledge concerning the role of early life genistein exposures in modifying breast cancer risk. She has long studied the link between soy use and breast cancer, as have her three co-authors, all Finnish researchers.

There have only been three human studies that tracked soy use during puberty and later breast cancer development, and two of them focused on Asian females, who eat soy in their traditional diet. But these studies suggest soy offers a very strong protective effect a 50 percent or more reduction in the risk of breast cancer - when soy is eaten during childhood and adolescence.

The strongest evidence for genisteins protective effect comes from studies in mice and rats, Hilakivi-Clarke says. For example, numerous studies in rats show that the data regarding pre
'/>"/>