Breast Cancer Risk: Effects of Tomato and Soy

Adana A.M. Llanos, PhD, MPH Assistant Professor, Department of Epidemiology RBHS-School of Public Health Rutgers, The State University of New Jersey Piscataway, NJ Interview with:
Adana A.M. Llanos, PhD, MPH
Assistant Professor, Department of Epidemiology
RBHS-School of Public Health
Rutgers, The State University of New Jersey
Piscataway, NJ 08854 What are the main findings of the study?

Dr. Llanos: Our 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 Ohio State University Comprehensive Cancer Center. For 10 weeks, 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. We examined the dietary intervention effects on hormone biomarkers known to be associated with obesity, namely adiponectin and leptin. After the tomato-rich diet participants’ levels of adiponectin climbed nine percent. The effect was slightly stronger in women who had a lower body mass index. 
Were any of the findings unexpected?

Dr. Llanos: The soy diet was linked to a reduction in study participants’ adiponectin levels. We originally hypothesized that a diet containing large amounts of soy could also have beneficial effects on adiponectin (specifically increasing adiponectin levels). But it may be that the protective effects of soy are limited to certain subgroups of women, such as those who regularly consume soy-rich diets and/or those who began consuming such diets earlier in life. What should clinicians and patients take away from your report?

Dr. Llanos: The main take away message from our study’s preliminary findings is that the beneficial effects of a diet high in lycopene on adiponectin may explain WHY tomatoes might be effective at reducing the risk of breast cancer in some women. What recommendations do you have for future research as a result of this study?

Dr. Llanos: While our findings are very preliminary, we believe regular consumption of at least the daily recommended servings of lycopene-containing fruits and vegetables would promote breast cancer prevention in a population at risk for breast cancer. Further, the findings demonstrate the importance of obesity prevention, given that the diet rich in tomatoes had a stronger impact on adiponectin levels in women with a lower body mass index.


Llanos AA, Peng J, Pennell ML, 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. 2013;doi:10.1210/jc.2013-3222.

Last Updated on December 21, 2013 by Marie Benz MD FAAD