a Overall, b Premenopausal and c Postmenopausal. Forest plot shows relative risks and 95% confidence intervals comparing highest category versus lowest category, using random-effect models. BWHS Black Women’s Health Study, CNBSS Canadian National Breast Screening Study, EPIC European Prospective Investigation into Cancer and Nutrition, FRiCaM Risk Factors for Breast Cancer: Fattori di Rischio per il Carcinoma della Mammella, JPHC Japan Public Health Center-based Prospective Study, KNCC Korean National Cancer Center Cohort, LSS The Radiation Effects Research Foundation’s Life Span Study, LWS Leisure World Study, MWS Million Women Study, NHS Nurses’ Health Study, NHSII Nurses’ Health Study II, NIH-AARP National Institute of Health-AARP Diet and Health Study, NLCS The Netherlands Cohort Study, SCHS the Singapore Chinese Health Study, UKWCS UK Women’s Cohort Study, VITAL VITamins And Lifestyle Cohort.