High intake of dietary fiber and whole grains leads to a healthier life, study finds
People who eat lots of high-fiber and whole grain foods have lower risk of heart disease, stroke, diabetes and other chronic diseases than people whose diets are low in fiber, a study commissioned by the World Health Organization (WHO) says, Reuters reported.
Observational studies and clinical trials conducted over nearly 40 years reveal the health benefits of eating at least 25g to 29g or more of dietary fibre a day, according to a series of systematic reviews and meta-analyses published in The Lancet.
For every 8 gram increase in fiber eaten a day, total deaths and incidences of heart disease, type 2 diabetes and bowel cancer fell by 5 to 27 percent, the study said. Protection against stroke and breast cancer also rose.
25g to 29g of dietary fiber a day
A good target for those wanting to reap health gains would be to eat 25g to 29g of dietary fiber a day, the analysis found. But the data also suggested higher dietary fiber intakes could give even greater protection.
Our findings provide convincing evidence for nutrition guidelines to focus on increasing dietary fiber and on replacing refined grains with whole grains. This reduces incidence risk and mortality from a broad range of important diseases,” said Jim Mann, a professor at the University of Otago, New Zealand who co-led the research.
Most people worldwide consume less than 20 g of dietary fibre per day. In 2015, the UK Scientific Advisory Committee on Nutrition recommended an increase in dietary fibre intake to 30 g per day, but only 9% of UK adults manage to reach this target. In the US, fibre intake among adults averages 15 g a day. Rich sources of dietary fibre include whole grains, pulses, vegetables and fruit.
Health benefits come from fiber’s chemistry
Mann said the health benefits of dietary fiber - contained in foods such as whole grains, pulses, vegetables and fruit - come from its chemistry, physical properties, physiology and its effects on metabolism.
Fiber-rich whole foods that require chewing and retain much of their structure in the gut increase satiety and help weight control, He said. “(And) the breakdown of fiber in the large bowel by the resident bacteria has additional wide-ranging effects including protection from colorectal cancer.”
While their study did not show any risks associated with dietary fibre, the authors note that high intakes might have ill-effects for people with low iron or mineral levels, for whom high levels of whole grains can further reduce iron levels. They also note that the study mainly relates to naturally-occurring fibre rich foods rather than synthetic and extracted fibre, such as powders, that can be added to foods.