In an article published online in the American Medical Association journal Archives of Internal Medicine on February 14, 2011, National Cancer Institute researchers reveal the outcome of a study which found a lower risk of dying over a nine year average follow up period among men and women who consumed a high fiber diet.
Yikyung Park, ScD and associates evaluated data from 219,123 men and 168,999 women who were aged 50 to 71 upon enrollment in the National Institutes of Health-AARP Diet and Health Study. Demographic, lifestyle and other information was collected at the beginning of the study and dietary questionnaire responses were analyzed for fiber intake. Men's intake of fiber range from 13 to 29 grams per day, and women's from 11 to 26 grams daily.
Over a nine year average, there were 20,126 deaths among the men and 11,330 among the women enrolled in the study. Participants whose intake of fiber was among the top 20 percent of subjects at 29.4 grams per day for men and 25.8 grams for women had a 22 percent lower risk of dying than those who consumed the least amount, which was 12.6 grams for men and 10.8 grams for women. Subjects with the highest fiber intake had a lower risk of dying from cardiovascular, infectious and respiratory disease compared to the group with the lowest intake, however, fiber only appeared to be protective against cancer in men, a finding that the authors attribute to the difference between genders in the leading organ sites for cancer death. When fiber intake was analyzed according to its source, fiber from grain was associated with a reduction of death from all causes as well as cancer, cardiovascular disease and respiratory disease.
In their introduction to the article, Dr Park and colleagues note that fiber "has been hypothesized to lower the risk of coronary heart disease, diabetes, some cancers, obesity, and premature death because it is known to (1) improve laxation by increasing bulk and reducing transit time of feces through the bowel; (2) increase excretion of bile acid, estrogen, and fecal procarcinogens and carcinogens by binding to them; (3) lower serum cholesterol levels; (4) slow glucose absorption and improve insulin sensitivity; (5) lower blood pressure; (6) promote weight loss; (7) inhibit lipid peroxidation; and (8) have anti-inflammatory properties."
"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," they remarked. "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."