Fiber is back in the news. Most people have heard it before; sugar and refined carbohydrates are bad, and vegetables and whole grains are good. However, a recent review of research, published in The Lancet, attempts to give a broader view of the effect that carbohydrate quality has on overall health. This new study is significant because most studies involving carbohydrate quality look at a single chemical marker or a single clinical outcome. Until now, no one has given an overview of the connection between carbohydrate quality and general health.
This was a comprehensive meta-analysis of studies published prior to February 2018. It included both prospective studies and randomized, placebo-controlled trials. The authors excluded any studies having to do with supplements, weight-loss, or where the participants had a chronic disease.
They looked at 185 prospective studies, involving nearly 135 million participants and 58 clinical trials with over 4600 subjects. The data revealed a significant decrease in coronary heart disease, stroke, type 2 diabetes breast cancer and colorectal cancer in subjects eating more whole grains and fiber when compared to those eating a lot of sugar and refined carbohydrates. Participants who consumed higher levels of fiber and whole grains in controlled clinical trials were found to have lower body weight, systolic blood pressure, and total cholesterol when compared to those who ate more refined carbohydrates.
The authors state, “Findings from prospective studies and clinical trials associated with relatively high intakes of dietary fibre and whole grains were complementary, and striking dose-response evidence indicates that the relationships to several non-communicable diseases could be causal. Implementation of recommendations to increase dietary fibre intake and to replace refined grains with whole grains is expected to benefit human health. A major strength of the study was the ability to examine key indicators of carbohydrate quality in relation to a range of non-communicable disease outcomes from cohort studies and randomised trials in a single study. Our findings are limited to risk reduction in the population at large rather than those with chronic disease.”