February 15, 2011

Dietary Fiber Lowers Mortality: Study

Adding some extra fiber to your diet may be linked to a lower 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, according to new research published online Monday in the Archives of Internal Medicine.

The government study, the largest of its kind, also links dietary fiber to a lower risk of cancer deaths in men, but not in women.  This may be because men are more likely to die from diet-related cancers, such as those of the esophagus and stomach, the researchers said.

Fiber, the edible part of plants that resist digestion, has been hypothesized to lower risks of heart disease, some cancers, diabetes and obesity, according to a background report about the study. 

It is also 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 of the National Cancer Institute 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.  Indeed, the 20 percent of men and women consuming the highest amount of 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 amount of fiber (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 both 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," wrote the researchers.

"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."

"A diet rich in dietary fiber from whole plant foods may provide significant health benefits," the study's authors concluded.

The study was published online February 14 in the Archives of Internal Medicine. 


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