Consuming up to 30 grams of natural dietary fiber – such as whole grains, legumes, vegetables and fruits – can daily prevent the risk of developing non-communicable diseases, according to a review of studies published in The Lancet.
The results suggest a reduction of 15 to 30 percent in all-cause and cardiovascular mortality; and reduced incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer by 16-24 percent.
Increased fiber intake is associated with lower body weight and cholesterol as compared to lower intake or synthetic and extracted fiber.
"Our findings provide compelling evidence that nutritional guidelines focus on increasing dietary fiber and replacing refined grains with whole grains. This reduces the risk of incidence and mortality from a wide range of major diseases," said Professor Jim Mann , of the University of Otago. New Zealand.
"Fiber-rich, whole foods that require chewing and retain much of their structure in the gut increase satiety and help weight control and can favorably influence lipid and glucose levels.
"The breakdown of fiber in the large intestine by resident bacteria has additional comprehensive effects, including protection against colorectal cancer," said Mann.
Protection against stroke and breast cancer has also increased. Consumption of 25 to 29 grams per day was adequate, but the data suggest that a higher intake of dietary fiber could provide even greater protection.
The researchers included 185 observational studies and 58 clinical trials involving 4,635 adult participants.
The study also found that diets with low glycemic index and low glycemic load provided limited support for protection against type 2 diabetes and stroke alone. Foods with low glycemic index or low glycemic load may also contain added sugars, saturated fats and sodium.
However, high intakes can have negative effects for people with low iron or mineral levels, for whom high levels of whole grains may further reduce iron levels, the researchers note.