Whole grain, bran and cereal fibre consumption and CVD: a systematic review

Abstract

Whole grain intake is associated with lower CVD risk in epidemiological studies. It is unclear to what extent cereal fibre, located primarily within the bran, is responsible. This review aimed to evaluate association between intake of whole grain, cereal fibre and bran and CVD risk. Academic databases were searched for human studies published before March 2018. Observational studies reporting whole grain and cereal fibre or bran intake in association with any CVD-related outcome were included. Studies were separated into those defining whole grain using a recognised definition (containing the bran, germ and endosperm in their natural proportions) (three studies, seven publications) and those using an alternative definition, such as including added bran as a whole grain source (eight additional studies, thirteen publications). Intake of whole grain, cereal fibre and bran were similarly associated with lower risk of CVD-related outcomes. Within the initial analysis, where studies used the recognised whole grain definition, results were less likely to show attenuation after adjustment for cereal fibre content. The fibre component of grain foods appears to play an important role in protective effects of whole grains. Adjusting for fibre content, associations remained, suggesting that additional components within the whole grain, and the bran component, may contribute to cardio-protective association. The limited studies and considerable discrepancy in defining and calculating whole grain intake limit conclusions. Future research should utilise a consistent definition and methodical approach of calculating whole grain intake to contribute to a greater body of consistent evidence surrounding whole grains.

Keywords: CRP C-reactive protein; HPFS Health Professionals Follow-up Study; HR hazard ratio; NHS Nurses’Health Study; RR relative risk; T2DM type 2 diabetes mellitus; Bran; CVD; Fibre; Systematic reviews; Whole grains.