Association of dietary fiber intake with all-cause and cardiovascular mortality in postmenopausal U.S. women: A NHANES 1999-2018 cohort study

BACKGROUND: Dietary fiber is known to confer various health benefits, yet its impact on long-term mortality in older women remains under-explored. This study investigated the association between dietary fiber intake and the risk of all-cause and cardiovascular disease (CVD) mortality among postmenopausal U.S. women. METHODS: We analyzed 7708 postmenopausal participants from the 1999-2018 National Health and Nutrition Examination Survey (NHANES) linked to mortality data (median follow-up 121 months). Dietary fiber intake (grams/day) was assessed via 24-h dietary recalls. Cox proportional hazards models estimated hazard ratios (HRs) for all-cause and CVD mortality, adjusting for factors such as age, sex, ethnicity, education, poverty-income ratio, smoking, alcohol use, physical activity, and body mass index. RESULTS: The mean baseline dietary fiber intake was 14.75 ± 7.5 g/day. During follow-up, 2116 deaths (27.5 %) occurred, including 657 CVD deaths (8.5 %). Fiber intake was inversely associated with mortality risk. For those consuming less than 7.9 g/day, each 5 g/day increase in fiber was linked to a 7 % reduction in all-cause mortality risk (HR = 0.93). Above 7.9 g/day, benefits diminished (HR = 0.99). Women in the highest fiber tertile had significantly lower mortality risks than those in the lowest tertile (all-cause HR = 0.85; CVD HR = 0.69). CONCLUSION: Higher dietary fiber intake is associated with reduced all-cause and CVD mortality, emphasizing the importance of adequate fiber consumption to older women's health and longevity.