People who eat higher levels of dietary fibre and whole grains may have a lower risk of developing non-communicable diseases, according to a review of studies published in The Lancet journal.
Observational studies and clinical trials conducted over nearly 40 years reveal the health benefits of eating at least 25 grammes to 29 grammes or more of dietary fibre a day, said researchers from the University of Otago in New Zealand.
The results suggest a 15-30 per cent decrease in all-cause and cardiovascular-related mortality when comparing people who eat the highest amount of fibre to those who eat the least. Eating fibre-rich foods also reduced the incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer by 16-24 per cent.
Per 1,000 participants, the impact translates into 13 fewer deaths and six fewer cases of coronary heart disease, researchers said. In addition, a meta-analysis of clinical trials suggested that increasing fibre intakes was associated with lower bodyweight and cholesterol, compared with lower intakes.
The study was commissioned by the World Health Organization to inform the development of new recommendations for optimal daily fibre intake and to determine which types of carbohydrate provide the best protection against non-communicable diseases (NCDs) and weight gain.
Most people worldwide consume less than 20 grammes of dietary fibre per day, researchers said. "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," said Professor Jim Mann from the University of Otago.
"Our findings provide convincing evidence for nutrition guidelines to focus on increasing dietary fibre and on replacing refined grains with whole grains. This reduces incidence risk and mortality from a broad range of important diseases," Mann said.
The researchers included 185 observational studies containing data that relate to 135 million person years and 58 clinical trials involving 4,635 adult participants. They focused on premature deaths from and incidence of coronary heart disease, cardiovascular disease and stroke, as well as incidence of type 2 diabetes, colorectal cancer and cancers associated with obesity: breast, endometrial, oesophageal and prostate cancer.
The researchers only included studies with healthy participants, so the findings cannot be applied to people with existing chronic diseases. For every eight grammes increase of dietary fibre eaten per day, total deaths and incidences of coronary heart disease, type 2 diabetes and colorectal cancer decreased by 5-27 per cent, researchers said.
Consuming 25 grammes to 29 grammes each day was adequate but the data suggest that higher intakes of dietary fibre could provide even greater protection, they said.