There are many well known benefits to eating a diet rich in fiber: It aids in regular bowel movements, lowers cholesterol levels, helps control blood sugar levels, and lowers blood pressure. A fiber-rich diet has been linked to a lower risk of heart disease, some forms of cancer, diabetes, and obesity. Now a new study suggests that eating a lot of fiber may increase longevity. Eat more fiber and you just may live longer.

An effective way to add fiber to one’s diet is to reduce the amount of animal protein consumed and eat more plant sources of protein, like beans and peas which provide 5 to 8 grams of fiber per serving. Nuts and seeds provide 1 to 3 gram of fiber per serving.

Fiber is the part of plant foods that the body cannot easily digest. The new Dietary Guidelines for Americans recommend an increase in the consumption of fiber through whole grains, seeds and nuts, and fresh fruits and vegetables. The recommendation is 14 grams of fiber per 1,000 calories per day, which averages roughly 25 grams of fiber a day for most Americans.

Researchers from the National Cancer Institute collected data from the National Institutes of Health-AARP Diet and Health Study which followed the health of nearly 400,000 AARP members over a period of nine years. In 1995 and 1996, when the study participants were between the ages of 51 and 71 years, they completed a questionnaire about their eating habits, smoking status, weight, and activity levels.

Researchers found that the fiber intake of the study participants ranged from 13 grams to 29 grams per day in men and from 11 grams to 26 grams per day in women.

During the next nine years, 20,126 men and 11,330 women died. The researchers found that those who ate the most fiber were 22% less likely to die of any cause than those who ate the least amount of fiber. A high intake of dietary fiber lowered the risk of death from cardiovascular, infectious, and respiratory diseases by 24% to 56% in men and by 34% to 59% in women.

The researchers observed that fiber from grains like whole-grain bread or brown rice seemed to reduce the risk of dying more so than fiber from fruits, vegetables, or beans. Also, eating more fiber was linked to a lower risk of cancer mortality for men, but not for women.

Yikyung Park, a staff scientist at the National Cancer Institute, remarked that while previous studies on fiber focused on the relationship between fiber intake and cardiovascular disease, there have been few studies that looked at the association between fiber intake and the risk of death from all causes. She noted that this study adds to the literature and suggests that a high fiber diet is associated with a reduced likelihood of death.

The study did not definitively prove that fiber prevents premature death. The researchers depended on the study participants to describe their diets accurately, and while things such as exercise and weight were factored into the study, it may be that people who eat a diet rich in whole grains, vegetables, fruits, beans and nuts, have healthier lifestyles than those who eat mostly processed foods and few high-fiber foods.

An effective way to add fiber to one’s diet is to reduce the amount of animal protein consumed and eat more plant sources of protein, like beans and peas which provide 5 to 8 grams of fiber per serving. Nuts and seeds provide 1 to 3 gram of fiber per serving. Eating the recommended 2 servings per day of fruit and 3 servings per day of vegetables will also increase fiber intake by 2 to 3 grams per serving. Whole-grain products provide 1 to 2 grams of fiber per serving. Food labels are required to list the amount of fiber per serving in a food, so consumers can easily see the fiber content of packaged foods.

The study was published in the February 14, 2011 online edition of the Archives of Internal Medicine.