By Shereen Lehman
(Reuters Health) - People who ate the most fiber were less likely to die of any cause 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 write in the American Journal of Epidemiology.
They pooled data from 17 previous studies that tracked 982,411 men and women, mostly in Europe and the U.S., and recorded about 67,000 deaths.
Yang's team divided participants into five groups based on their daily fiber intake. Those in the top fifth, who ate the greatest amount of fiber daily, were 16 percent less likely to die than those in the bottom fifth, who consumed the least amount of fiber.
In addition, eight studies showed a 10 percent drop in risk for any cause of death with each 10-gram per day increase in fiber intake.
The U.S. Department of Agriculture recommends that adults consume 14 grams of fiber in every 1,000 calories they take in, the authors point out. That translates to approximately 25 grams a day for women and 38 grams daily 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-analyzes 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."
It's not difficult to consume an extra 10 grams of fiber per day, Burley said. "This can come from two servings of whole grain foods, such as breakfast cereal and two servings of fruit or vegetables, for example."
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. "Although there is increasing evidence that cereal grains may offer the best risk reductions for colorectal and cardiovascular disease," she said.
Burley 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, suggests reading labels and choosing foods with at least three grams of fiber per serving. She also encourages eating a variety of foods that are high in fiber at each meal and snack, such as fresh fruit and vegetables, whole grains, beans, legumes, seeds and nuts.
Shapiro said to be careful when going from a low-fiber diet to a high-fiber diet.
"Your body needs time to adjust, so increase fiber content slowly and make sure to consume extra water while doing so to help with digestion," she told Reuters Health in an email.
SOURCE: http://bit.ly/1zRqnHa American Journal of Epidemiology, online December 31, 2014.