A tomato-rich diet may help protect postmenopausal women from breast cancer, according to new research published this week in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism.
As their body mass index climbs, postmenopausal women are at an increased risk for breast cancer. The study found that women who consumed a diet high in tomatoes had higher levels of adiponectin, a hormone involved in regulating blood sugar and fat metabolism. Higher adiponectin levels have been shown in prior studies to be associated with reduced risk of breast cancer.
"The advantages of eating plenty of tomatoes and tomato-based products, even for a short period, were evident in our findings," said the study's first author, Adana Llanos, an assistant professor of epidemiology at Rutgers University School of Public Health and a research member at Rutgers Cancer Institute of New Jersey. Llanos was a postdoctoral fellow at The Ohio State University Comprehensive Cancer Center - Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC) - when she conducted this research.
Llanos said that eating fruits and vegetables rich in essential nutrients, vitamins, minerals and phytochemicals - such as lycopene, an antioxidant found in tomatoes - conveys significant benefits. Based on these data, Llanos said, "we believe regular consumption of at least the daily recommended servings of fruits and vegetables could promote breast cancer prevention in an at-risk population."
The longitudinal study examined the effects of both tomato-rich and soy-rich diets in a group of 70 postmenopausal women who participated in the study at The OSUCCC. For 10 weeks, the women ate tomato products containing at least 25 milligrams of lycopene daily. For a separate 10-week period, the participants consumed at least 40 grams of soy protein daily. Before each test period began, the women were instructed to abstain from eating both tomato and soy products for two weeks.
When they followed the tomato-rich diet, participants' levels of adiponectin - climbed 9 percent. The effect was slightly stronger in women who had a lower body mass index.
"The findings demonstrate the importance of obesity prevention," Llanos said. "Consuming a diet rich in tomatoes had a larger impact on hormone levels in women who maintained a healthy weight."
"The take-home message from our study's preliminary findings is that the beneficial effects of a diet high in lycopene, specifically increasing adiponectin, may explain why tomatoes may be effective at reducing breast cancer risk," she says.
The soy diet was linked to a reduction in participants' adiponectin levels. Researchers originally theorized that a diet containing large amounts of soy could be part of the reason that Asian women have lower rates of breast cancer than women in the United States. The benefits, however, may be limited to certain ethnic groups, Llanos said.
SOURCE The Endocrine Society