Dietary Fiber Intake Was Inversely Associated with All-Cause Mortality but Not with Cancer and Cardiovascular Disease Mortalities in the US

Background: Evidence linking dietary fiber intake with cancer risk and mortality is equivocal. Objective: We investigated the relationship between dietary fiber intake and all-cause, cancer, and cardiovascular disease (CVD) mortalities in US adults ≥ 20 years. Methods: Data from the National Health and Nutrition Examination Surveys (NHANES) from 2003 to 2016 were used. Seven two-year cycles were concatenated into one analytic data file, NHANES 2003–2016 (n = 25,868; age ≥ 20 years). Dietary fiber intakes were collected from one 24-h dietary recall. Fiber intakes were categorized into quartiles. Mortality information was obtained from data linkage. To determine mortality, subjects were followed up for 6.4 years. Association between dietary fiber and mortality from all causes, cancer, and CVD was determined with multivariable-adjusted Cox proportional hazards models. Multivariate-adjusted Cox proportional hazard regression was used to generate mortality survival rates. Results: During the follow-up period, out of 2520 deaths, 561 and 511 deaths were from cancer and CVD, respectively. Dietary fiber intake was inversely associated with all-cause mortality [RR (95% CI), 0.67 (0.56–0.80); p ≤ 0.001]. No relationship was observed between fiber intake and cancer mortality [RR (95% CI), 0.8 (0.55–1.17); p = 0.51] and CVD mortality [RR (95% CI), 0.84 (0.53–1.33); p = 0.67]. Conclusions: In the US population, dietary fiber intake was associated with decreased all-cause mortality, but not with cancer and CVD mortality.