Can whole grain foods help prevent heart disease, diabetes, and cancer?
A New Zealand study published in The Lancet quantifies how much whole grain foods one should eat to prevent diseases and maintain health and wellness.
Whole grain foods have long been linked to different health benefits. Whole grain foods include barley, brown rice, buckwheat, oatmeal and whole wheat products. Whole grain foods, as well as fruits and vegetables, are a healthy source for fibers, starches, and vitamins. People with heart diseases, diabetes and even certain cancers are firmly advised to consume whole grain products and vegetables on a constant basis to support their health.
Not enough evidence on the amount of whole grain foods to eat for certain diseases
As established as the current recommendations may be, no quantitative dietary instruction is available for any specific disorder. Professor Jim Mann, from the University of Otago, New Zealand, explains in a press release, “Previous reviews and meta-analyses have usually examined a single indicator of carbohydrate quality and a limited number of diseases so it has not been possible to establish which foods to recommend for protecting against a range of conditions”.
In other words, doctors cannot tell you how much fibers and whole grains you should eat to take care of yourself in a certain disease, simply because there is not enough scientific evidence to support their recommendations. Professor Jim Mann is one of the researchers working to resolve this problem.
In a recent study, published in The Lancet, Mann and his group of co-authors looked for a detailed answer by examining previous studies on carbohydrate quality and non-communicable diseases. Their study covers nearly 40 years of scientific data and clinical trials data generation. Specifically, the authors examined how mortality and major disease incidence is affected by the quality of carbohydrates consumed by patients.
Eating high amounts of fiber is associated with lower incidence of diseases
The study found that individuals who eat the highest amount of fiber have a 15-30% decrease in mortality due to all causes or mortality due to heart-related events compared to those who eat the lowest amount of fiber. They also found that eating foods rich in fiber reduced the incidence of coronary heart disease, stroke, type 2 diabetes, and colorectal cancer by 16-24%.
The researchers note that about 30 g of fibers a day are needed to promote good health and additional benefits. Whole grain foods, pulses, fruits and vegetables are the best source for dietary fibers. Unfortunately, today, we eat much less fibers than we need; about 20 g and 15 g of fiber a day are recommended for a healthy British and American grow-ups, respectively.
The study has some limitations including only considering the effects among healthy adults. Nevertheless, these findings are very important in terms of setting clear dietary instructions. The World Health Organization, who sponsored this work, will now use the results to further develop evidence-based informative dietary recommendations.
Written by Marina Chemerovski-Glikman, PhD
Reference: Reynolds A, Mann J, Cummings J, Winter N, Mete E, Morenga LT. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. 2019.
