Dietary Fiber Intake and Total Mortality: A Meta-analysis of Prospective Cohort Studies

Youngyo Kim; Youjin Je

Disclosures

Am J Epidemiol. 2014;180(6):565-573. 

In This Article

Abstract and Introduction

Abstract

Greater intake of dietary fiber has been associated with lower risk of several chronic diseases. Some observational studies have examined the association between dietary fiber intake and total mortality, but the results were inconclusive. We conducted a meta-analysis of data from prospective cohort studies to quantitatively assess the association. Eligible studies were identified by searching the PubMed and Embase databases for all articles published through November 30, 2013, and by reviewing the reference lists of retrieved articles. Study-specific estimates adjusting for potential confounders were combined to calculate a pooled relative risk and 95% confidence interval using a random-effects model. Seven prospective cohort studies of dietary fiber intake and total mortality, including 62,314 deaths among 908,135 participants, were identified. The pooled adjusted relative risk of total mortality for the highest category of dietary fiber intake versus the lowest was 0.77 (95% confidence interval: 0.74, 0.80). In a dose-response meta-analysis, the pooled adjusted relative risk for a 10-g/day increment of dietary fiber intake was 0.89 (95% confidence interval: 0.85, 0 92). By source of fiber, cereal and, to a lesser extent, vegetable fiber were significantly associated with lower total mortality, while fruit fiber showed no association. In conclusion, high dietary fiber intake may reduce the risk of total mortality.

Introduction

Dietary fiber is defined as the parts of plant foods that are indigestible by humans; it includes polysaccharides, lignin, and oligosaccharides.[1] Generally, dietary fiber has been associated with decreased constipation and improved intestinal health. In addition, it provides many other health benefits, including decreasing plasma lipid levels,[2] lowering blood pressure,[3] stabilizing blood glucose levels,[4] and reducing inflammation.[5] Accumulating evidence from observational studies indicates that dietary fiber could act as a protective factor against diseases such as stroke,[6] some types of cancer,[7,8] type 2 diabetes,[9] and cardiovascular disease,[10] which are major causes of death. A relatively small number of observational studies have been performed to investigate the relationship between fiber intake and total mortality, and the results were inconsistent.[11–17] Thus, we conducted a systematic review and meta-analysis of data from prospective cohort studies to quantitatively assess the association between fiber intake and total mortality.

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