Nutrition guidelines encourage us to eat more vegetables, fruits, and whole grains. Despite media attention surrounding the amount of carbohydrates that we consume, there are fewer quantitative guidelines regarding the quality of the carbohydrates that we eat. As such, a study was commissioned by the World Health Organization (WHO) to help update recommendations on carbohydrate intake.
Researchers systematically reviewed the literature and analyzed 185 prospective studies and 58 clinical trials, pooling data from 4,635 adults. They reviewed studies that focused on the relationship between carbohydrate quality (e.g. fiber and whole grains) and mortality as well as the incidence of coronary heart disease, type 2 diabetes, and other diseases.
Those who ate the most fiber had a 15-31% decrease in all-cause mortality and cardiovascular disease related mortality compared with those who ate the least fiber. Eating fiber-filled foods also reduced the incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer by 16-24%. The authors recommended increasing fiber intake to at least 25–29 g per day.
Higher whole grain intake was also associated with reductions in disease risk; a low-glycemic index diet offered smaller or no risk reductions.
Study quality varied, with evidence graded as moderate for dietary fiber, low to moderate for whole grains, and low to very low for dietary glycemic index.
The authors also note that, instead of supplementing with synthetic or extracted fiber, such as powders,
…dietary advice should emphasise the benefits of naturally occurring dietary fibre in whole grains, vegetables, and fruits that have been minimally processed.
Reynolds, A., Mann, J., Cummings, J., Winter, N., Mete, E., & Te Morenga, L. (2019). Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet.
