Diet Rich in Tomatoes May Lower Breast Cancer Risk

Eating plenty of tomatoes and tomato-based products may help protect at-risk postmenopausal women from breast cancer, according to a new study in the Journal of Clinical Endocrinology and Metabolism.

Researchers found that among postmenopausal women with increased breast cancer risk, a tomato-rich diet favorably modified concentrations of adiponectin—a hormone involved in regulating blood sugar and fat metabolism.

“We hypothesize that the mechanism by which this diet may help lower breast cancer risk involves the adipokine biomarkers and pathways of obesity and inflammation,” says first author Adana Llanos, PhD, MPH, an assistant professor of epidemiology at Rutgers University School of Public Health and a research member at Rutgers Cancer Institute of New Jersey. “This is important because obesity and inflammation are both known to be related to increased breast cancer risk among postmenopausal women.”

Llanos and colleagues conducted a longitudinal study to examine the effects of both tomato-rich and soy-rich diets in 70 postmenopausal women at the Ohio State University Comprehensive Cancer Center in Columbus, Ohio. The women ate tomato products containing at least 25mg of lycopene daily for 10 weeks, and consumed at least 40g of soy protein daily for a separate 10-week period.

“We found that following the 10-week tomato-based dietary intervention, among the postmenopausal women enrolled in the study, there was a significant 9% increase in serum adiponectin levels (considered a beneficial effect), which was stronger among women who had a lower body mass index,” Llanos says.

Tomatoes are high in lycopene as well as other nutrients, vitamins, minerals, and bioactive phytochemicals. “While tomatoes are the best source of lycopene, small amounts are also found in guavas, watermelons, apricots, papayas, and pink grapefruits,” Llanos says. “So we think that encouraging patients to consume a minimum of five servings of fruits and vegetables daily would be a good start to promote better health.”

She and her colleagues are interested in studying the effects of this diet and others on biomarkers of breast cancer risk in younger women. They would also like to better understand the specific mechanisms that may make certain phytonutrients, such as the lycopene found in tomatoes, practical chemopreventive agents.

—Colleen Mullarkey

Reference

Llanos AA, Peng J, Pennell ML, Krok JL, Vitolins MZ, Degraffinreid CR, et al. Effects of tomato and soy on serum adipokine concentrations in postmenopausal women at increased breast cancer risk: A cross-over dietary intervention trial. J Clin Endocrinol Metab. December 18, 2013. [Epub ahead of print].