Carbohydrate quality and human health: a series of systematic reviews and meta-analyses (fibre & whole grains)
Umbrella synthesis (185 prospective studies + 58 RCTs): higher dietary fibre intake was associated with roughly 15–30% lower all-cause and cardiovascular mortality and lower incidence of coronary disease, stroke, type 2 diabetes, and colorectal cancer comparing highest vs lowest consumers; RCTs showed lower weight, systolic BP, and total cholesterol with higher fibre.
Scope
Lancet commission-style umbrella work quantifying dietary fibre, whole grains, and glycaemic index/load vs a basket of NCD incidence and mortality endpoints plus selected risk factors in RCTs.
Headline observational fibre signals (abstract)
Highest vs lowest dietary fibre associated with roughly 15–30% lower rates of all-cause mortality, CV mortality, CHD, stroke incidence & mortality, type 2 diabetes, and colorectal cancer (pooled prospective data).
Trial risk-factor signals
Higher vs lower fibre intakes in RCTs: lower body weight, SBP, and total cholesterol (significant).
Dose narrative
Abstract highlights 25–29 g/day fibre as a band where risk reductions were largest across several endpoints, with possible greater benefit at still higher intakes on dose–response curves.
Evidence hygiene
Mostly observational incidence/mortality plus short/medium RCT risk factors—GRADE moderate for fibre, low–moderate for whole grains, low–very low for GI/GL per abstract.
Publication
Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Lancet. 2019 Feb 2;393(10170):434-445. PMID 30638909.
Outcomes
- RCTs: significantly lower body weight, systolic blood pressure, and total cholesterol when comparing higher with lower dietary fibre intakes (exact pooled mmHg in supplementary tables; abstract signals trial-level BP benefit).
- Prospective pooled associations: highest vs lowest dietary fibre consumers had ~15–30% lower all-cause and cardiovascular mortality and lower incidence of CHD, stroke, T2D, and colorectal cancer (per abstract; GRADE moderate for fibre).