Carbohydrate quality and human health: a series of systematic reviews and meta-analyses.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials and prospective observational studies.
PubMed 30638909 · doi:10.1016/S0140-6736(18)31809-9
What was done
Authors conducted a series of systematic reviews and meta-analyses of prospective cohort studies (inception to April 2017) and randomized controlled trials (inception to February 2018) examining carbohydrate quality markers (dietary fibre, whole grains, glycaemic index, and glycaemic load) in relation to non-communicable disease incidence, mortality, and risk factors. Studies in participants with baseline chronic diseases, weight-loss trials, and supplement trials were excluded. Random-effects models, dose-response analyses, and GRADE certainty assessments were applied.
What was found
Across 185 prospective studies (nearly 135 million person-years) and 58 trials (4,635 adults), comparing the highest with lowest dietary fibre intake was associated with a 15–30% reduction in all-cause mortality, cardiovascular-related mortality, stroke incidence and mortality, coronary heart disease, type 2 diabetes, and colorectal cancer. Randomized trials showed significant reductions in body weight, systolic blood pressure, and total cholesterol with higher fibre intake. Risk reduction was greatest at 25–29 g daily fibre intake, with dose-response curves suggesting further benefits at higher intakes. Similar associations were seen for whole grains, but smaller or no risk reductions were found for low versus high glycaemic index or load.
Why it matters
This review provides quantitative evidence to support dietary recommendations aiming for at least 25–29 g/day of dietary fibre and the replacement of refined grains with whole grains to reduce non-communicable disease burden and mortality.
Limits
Findings apply to general adult populations and may not generalize to individuals with established chronic diseases. The GRADE certainty was moderate for fibre, low to moderate for whole grains, and low to very low for glycaemic index and load; data on other carbohydrate indicators were scarce.
Cited by
- supports Cohort studies consistently demonstrate that dietary fiber intake is associated with reduced risk of cardiovascular disease, cancer, and all-cause mortality in a dose-response manner.