The WHI is an ongoing national study that enrolled 161,808 postmenopausal women aged 50-79 at baseline, enrolled during 1993-1998. Data collection at screening and enrollment included questionnaires completed by self-report or interview, physical examination, and blood specimen collection. Information on soda intake (total, caffeinated and caffeine-free) was collected at the sixth follow-up year in the OS among 79,885 women who form the baseline study population for this analysis. After exclusion of participants who had incomplete exposure information (n=5,413), had previous history of hip fracture (n=471), or less than one day of follow up after Year 6 (n=1659), a cohort of 72,342 participants contributing 700,388 person/years of follow-up was used for the prospective analysis. All participants provided informed consent at baseline and subsequently for extended follow-up.