Dietary fiber may be associated with a reduced risk of death from cardiovascular, infectious and respiratory diseases, as well as a reduced risk of death from any cause over a nine-year period.
The study will be published in the Archives of Internal Medicine.
Fiber, the edible part of plants that resist digestion, has been hypothesized to lower risks of heart disease, some cancers, diabetes and obesity.
It is known to assist with bowel movements, reduce blood cholesterol levels, improve blood glucose levels, lower blood pressure, promote weight loss and reduce inflammation and bind to potential cancer-causing agents to increase the likelihood they will be excreted by the body.
Yikyung Park, Sc.D., of the National Cancer Institute, Rockville, Md., and colleagues analyzed data from 219,123 men and 168,999 women in the National Institutes of Health-AARP Diet and Health Study. Participants completed a food frequency questionnaire at the beginning of the study in 1995 and 1996. Causes of death were determined by linking study records to national registries.
Participants’ fiber intake ranged from 13 to 29 grams per day in men and from 11 to 26 grams per day in women. Over an average of nine years of follow-up, 20,126 men and 11,330 women died. Fiber intake was associated with a significantly decreased risk of total death in both men and women-the one-fifth of men and women consuming the most fiber (29.4 grams per day for men and 25.8 grams for women) were 22 percent less likely to die than those consuming the least (12.6 grams per day for men and 10.8 grams for women).
The risk of cardiovascular, infectious and respiratory diseases was reduced by 24 percent to 56 percent in men and 34 percent to 59 percent in women with high fiber intakes. Dietary fiber from grains, but not from other sources such as fruits, was associated with reduced risks of total, cardiovascular, cancer and respiratory disease deaths in men and women.
“The findings remained robust when we corrected for dietary intake measurement error using calibration study data; in fact, the association was even stronger with measurement error correction,” the authors write.
“The current Dietary Guidelines for Americans recommend choosing fiber-rich fruits, vegetables and whole grains frequently and consuming 14 grams per 1,000 calories of dietary fiber,” the authors conclude. “A diet rich in dietary fiber from whole plant foods may provide significant health benefits.”
Dietary fiber is a type of carbohydrate that cannot be broken down by digestive enzymes. Because of this, the fiber passes through the digestive tract more quickly, aiding in elimination. The term “dietary fiber” includes the cellulose found in plant cell walls and the chitin that makes up the support tissues of fungi (mushrooms), crustaceans, and insects.
In 2001 the U.S. National Academy of Sciences Institute of Medicine (IOM) recommended that “dietary fiber” be defined as the nondigestible carbohydrates and lignin that are intrinsic and intact in plants and that the term “added fiber” be used to characterize isolated, nondigestible carbohydrates that are added to foods or supplements. Defined as such, dietary fiber includes nonstarch polysaccharides (NSP) and oligosaccharides that cannot be digested in the small intestine by alpha amylase or any of the sugar-hydrolyzing enzymes in the gut.
In summary, dietary fiber has specific attributes that promote the normal functioning of the gastrointestinal tract. In addition, actions of fiber contribute to the ability of plant foods to lower the risk of chronic disease; however, it is difficult to isolate the effects of fiber from the overall response to a diet rich in plant foods, which provides many compounds that contribute to a lower risk of disease. As a consequence most recommendations of dietary fiber emphasize the importance of consuming foods high in fiber rather than relying on isolated fiber supplements.
Source: Archives of Internal Medicine, USA