The daughters of rats that feast on whole wheat during pregnancy are less likely to develop breast cancer, a new study shows.

Based on the findings, “it might be beneficial to include whole wheat in the diet when one is expecting,” Dr. Leena Hilakivi-Clarke of Georgetown University in Washington, DC, the study’s lead author, told Reuters Health.

Hilakivi-Clarke and her colleagues have used rodents to evaluate a number of dietary factors in pregnancy on offspring’s health risks, she added, for example showing that daughters of mothers fed a high-fat diet were at greater risk of breast cancer. “The model we’re using should be relatively valid to make assumptions about what’s going on in humans,” she added.

Some researchers have suggested that fiber may reduce breast cancer risk by bringing down levels of circulating estrogen, since the hormone can stimulate tumor growth, she and her colleagues note in their report. But evidence for an association between dietary fiber and breast cancer in humans has been mixed, and animal studies suggest that the type of fiber eaten may be a key factor.

To investigate, she and her colleagues examined the effects of feeding pregnant rats diets containing 6 percent fiber from whole wheat flour, oat flour, defatted flax flour, or cellulose as a control. Their offspring were then given a breast-cancer-inducing chemical.

The rats whose mothers had been fed the whole wheat diet were less likely to develop breast tumors, the researchers found, while those given defatted flax flour were at increased cancer risk. Giving mothers oat flour had no effect on their offspring’s breast cancer risk.

Measurements of several markers of cell growth and death suggested that the whole wheat might somehow improve the animals’ ability to repair DNA damage, Hilakivi-Clarke and her team conclude in the November in the International Journal of Cancer.

Building an understanding of how diet influences cancer risk both in the womb and after birth could one day allow people to modify these risks by eating-or avoiding-certain, foods, the researcher noted.

SOURCE: International Journal of Cancer, November 15, 2006.