Diets high in vegetables, fruits and soy might cut the risk of developing breast cancer by 30 percent, new research suggests.

In a study, Dr. Lesley M. Butler, of Colorado State University and colleagues, noticed a trend of “decreasing breast cancer risk with increasing intake of a vegetable-fruit-soy dietary pattern” in the 34,000 Chinese women studied.

Even though the researchers identified and analyzed dietary patterns among Chinese women from Singapore, Butler believes the findings are relevant for American women.

The diets “aren’t that different from patterns seen in US populations,” the lead investigator told Reuters Health.

“There’s usually a bad food pattern of meat and lots of starch and saturated fat. And then there’s the good pattern - a prudent pattern in our case - the vegetable-fruit-soy pattern,” she said.

For their study, reported in the American Journal of Clinical Nutrition, Butler and her colleagues used data collected between 1993 and 1995 from 63,257 men and women in the Singapore Chinese Health Study (SCHS).

The large health study used in-person interviews to gather information about diet, weight, education, smoking and exercise habits, and hormone use.

Previous research focusing on individual foods or nutrients has been inconsistent, the authors note.

The SCHS data, however, allowed Butler’s group to identify two dietary patterns: the meat-starch-saturated-fat based “meat-dim sum” pattern and the “vegetable-fruit-soy” pattern characterized by lots of cruciferous vegetables such as broccoli, cauliflower, Brussels sprouts, kale, cabbage, and bok choy.

Based on their self-reported intake of 165 foods, participants were assigned a score for the vegetable-fruit-soy and the meat-dim sum dietary patterns.

Butler’s group identified 34,028 women with no history of breast cancer in the data. All women were between the ages of 45 and 74. For the most part, they were thin, they exercised, had gone through menopause, and few smoked or used hormone replacement therapy.

By the end of 2005, 10 years after the enrollment interviews, 629 breast cancer cases had been identified in the Singapore Cancer Registry among study participants.

After analyzing the data, the study authors found that the greater the intake of vegetables, fruits and soy, the lower the breast cancer risk among post-menopausal women.

The researchers did not find an association between higher meat-dim sum consumption and increased breast cancer risk, as suggested in other studies. Butler cautioned, however, that Americans shouldn’t read too much into this finding because the discrepancy could be explained by the way meat is prepared.

Stir-fried meats don’t contain as many Heterocyclic Amines (HCAs) that result from cooking muscle meats at high temperatures. Researchers have identified 17 HCAs that may be associated with increased cancer risk. “The charred barbeque meat that we love contains a lot of these carcinogens,” Butler said.

Despite the cultural differences, Butler believes American women can learn from these study findings. “Eating a diverse diet that can be characterized as having a lot of fruits and vegetables, and possibly adding soy also, would be beneficial,” she said.

SOURCE: American Journal of Clinical Nutrition, February 2010.