The focus of my research has been women's health, particularly the role of lifestyle factors, moderate-intensity versus vigorous exercise, diet, micronutrient supplementation, vitamin D, omega-3 fatty acids, folic acid, and estrogen therapy as determinants of chronic disease in women. Another major interest is the assessment of endocrinologic predictors of breast cancer, including the role of biochemical and genetic biomarkers. Utilizing epidemiologic methods in large-scale prospective cohort studies and randomized clinical trials, I have collaborated on studies of biomarkers (including sex steroid hormones and genetic markers) in predicting risk of breast cancer, as well as other cancer epidemiology studies. I serve as Principal Investigator of several NIH-funded research studies, including the VITamin D and OmegA-3 TriaL (VITAL); the Women’s Health Initiative Clinical Center, Boston site, since study inception; the Women’s Folic Acid Cardiovascular Study, and the CVD component of the Nurses’ Health Study, among others. I am also one of the PIs of the Cocoa Supplement and Multivitamins Outcomes Study (COSMOS).