Association between dietary fibre intake with cancer and all-cause mortality among 15 740 adults: the National Health and Nutrition Examination Survey III

Background: Few prospective studies have examined the longitudinal associations of total dietary fibre intake and water insoluble and soluble fibres with cancer and all-cause mortality. The present study aimed to examine these associations. Methods: We studied the effects of total dietary fibre intake and water insoluble and soluble fibres on cancer and all-cause mortality, using data from 15 740 adult participants [mean (SD) age: 44.53 (19.22) years, 46.60% male] in the National Health and Nutrition Examination Survey (NHANES) III, 1988-1994, who had completed a 24-h dietary recall. Death certificate data were obtained up to 2006. Participants had been followed for 13.74 years on average. Cox regression was used to estimate the hazard ratios (HRs) of total dietary, insoluble and soluble fibres on cancer and all-cause mortality, with the first quartile as the reference group, adjusted for demographics, lifestyle and dietary factors. Results: Relative to those in the first quartile of total fibre intake, only the third quartile was associated with all-cause mortality, with an adjusted HR of 0.87 [95% confidence interval (CI) = 0.79, 0.97, P = 0.021], and cancer mortality, with an adjusted HR of 0.77 (95% CI = 0.61, 0.99, P = 0.05). The third quartile of insoluble fibre intake was associated with cancer mortality, with an adjusted HR of 0.76 (95% CI = 0.60, 0.96, P = 0.023), and colorectal-anal cancer mortality (in grouped data as provided for public use), with an adjusted HR of 0.42 (95% CI = 0.19, 0.91, P = 0.03). Conclusions: Dietary fibre showed protective benefits in terms of mortality risk. Investigating the mechanisms and components of dietary fibres underlying the different protective benefits remains an important consideration for research on fibre-mortality risk.