Higher-fiber diet linked to lower mortality

Last Updated: 2015-01-12

By Shereen Lehman

(Reuters Health) - People in the top quintile for fiber consumption were less likely to die of any cause compared to those in the bottom quintile, during a recent study of nearly one million people.

The finding might be explained by fiber's potential to lower the risk of chronic diseases including heart disease, stroke, diabetes and several types of cancer, researchers say.

Individuals should be encouraged to increase their dietary fiber intake "to potentially decrease the risk of premature death," Yang Yang, of the Shanghai Cancer Institute in China, and colleagues wrote December 31 in the American Journal of Epidemiology.

They pooled data from 17 studies that tracked 982,411 men and women, mostly in Europe and the U.S., and recorded about 67,000 deaths.

Participants in the top quintile for daily fiber intake were 16% less likely to die than those in the bottom fifth, they found.

In addition, eight studies showed a 10% drop in risk for any cause of death with each 10-g per day increase in fiber intake.

The U.S. Department of Agriculture recommends that adults consume 14 g of fiber in every 1,000 calories they take in, the authors point out. That translates to approximately 25 g/day for women and 38 g/day for men.

"On average, intakes of dietary fiber in the U.S. and other economically developed countries are much lower than recommended goals - in the U.S., about half of what is advised," said Victoria Burley, a nutrition researcher at the University of Leeds in the UK, who was not involved in the study.

These study results are "very much in line with earlier published meta-analyses of the relationship between dietary fiber and risk of major chronic diseases such as cardiovascular disease, and cancers," Burley told Reuters Health in an email.

She said the benefits of consuming fiber-rich foods have been known for decades, including lowering of blood cholesterol, blood pressure, blood glucose and insulin, and possibly reducing inflammation.

High-fiber foods may also make people feel full sooner, and for longer, which helps curb overeating and weight gain, she added. "Some or all of these factors may underlie the reduction in mortality observed here."

She cautioned, however, that the current study does not prove that eating more fiber is the reason some participants lived longer. Their reduced risk of death might be due to some other shared characteristic, like an overall healthier lifestyle, or perhaps some other property of the high-fiber foods, which tend to be nutritious in general.

Little is known about the best sources of fiber for reducing disease risk - whether the best sources are fruit and vegetables, legumes or grains, Burley pointed out.

Burley also said the study findings do not suggest taking dietary fiber supplements will have the same impact as eating fiber-rich foods.

Jessica Shapiro, a wellness dietitian at Montefiore Medicine Center in New York, advises patients to read labels and choose foods with at least three grams of fiber per serving.

Shapiro warns patients to be careful when going from a low-fiber diet to a high-fiber diet - to increase fiber content slowly and make sure to consume extra water while doing so.

SOURCE: http://bit.ly/1zRqnHa

Am J Epidemiol 2014.