Eating more dietary fiber and whole grains protects against noncommunicable diseases (NCDs), such as coronary heart disease (CHD), stroke, type 2 diabetes, and colorectal cancer, according a new review commissioned by the World Health Organization (WHO) and published in The Lancet.
Although nutrition guidelines issued by governments and professional organizations encourage increased consumption of vegetables, fruits, and whole grains, there are fewer quantitative guidelines regarding sources and intake of dietary fiber and starch, the authors wrote. The motive of the study was to inform the development of updated WHO recommendations regarding carbohydrate intake.
Researchers reviewed and meta-analyzed 40 years of studies, including 185 observational studies with data encompassing 135 million person-years and 58 clinical trials, involving 4,635 participants. They excluded prospective studies and trials reporting on participants with a chronic disease, and weight loss trials or trials involving supplements.
The researchers found that eating at least 25 g to 29 g of dietary fiber a day yielded significant health benefits, decreasing both total deaths and the incidence of CHD, type 2 diabetes, and colorectal cancer. There was a 15% to 31% reduction in the risk for all-cause mortality and CVD-related mortality for those who ate the highest quantity of fiber, compared with those who ate the least. For all-cause mortality and CHD incidence, this reduction translated into 13 fewer deaths and six fewer cases of CHD per 1,000 participants over the duration of the studies. For every 8 g increase in dietary fiber consumed daily, total deaths and incidents of CHD, type 2 diabetes, and colorectal cancer decreased by 5% to 17%. There was also increased protection against stroke and breast cancer.
In addition, a higher consumption of whole grains was associated with a 13% to 33% reduction in NCD risk, which translated into 26 fewer deaths per 1,000 people from all-cause mortality and seven fewer cases of CHD per 1,000 people over the duration of the studies. Moreover, for every 15 g increase in daily consumption of whole grains, total deaths and the incidence of CHD, type 2 diabetes, and colorectal cancer decreased by 2% to 19%.