Dietary fiber is a term used for the parts of plants that the human body can't digest. There are two types of fiber: soluble and insoluble. Foods that include a lot of soluble fiber include oat bran, oatmeal, beans, peas, rice bran, barley, citrus fruits, strawberries, and apple pulp. Foods that have lots of insoluble fiber include whole-wheat breads, wheat cereals, wheat bran, rye, rice, barley, most other grains, cabbage, beets, carrots, Brussels sprouts, turnips, cauliflower and apple skin.

For example, half a cup of cooked beans has 6.2-9.6 grams of fiber, half a cup of 100% ready to eat bran cereal has 9.1 grams of fiber, one cup of cooked broccoli has 5.2-5.6 grams of fiber, one medium pear has 5.5 grams of fiber, while an ounce of almonds has 3.5 grams of fiber.

The American Heart Association recommends that adults consume at least 25 grams of fiber per day. Soluble fiber is associated with decreased LDL ("bad") cholesterol levels, while insoluble fiber has been associated with decreased cardiovascular risk and slower progression of cardiovascular disease in high-risk individuals.

New research presented last week at the American Heart Association's Nutrition, Physical Activity and Metabolism/Cardiovascular Disease Epidemiology and Prevention Scientific Sessions 2011 in Atlanta, Georgia concluded that a high-fiber diet could be a critical heart-healthy lifestyle change young and middle-aged adults can make. The study found that for adults between 20 and 59 years old, higher fiber intake was significantly associated with lower estimated lifetime risk for cardiovascular disease compared with lower fiber intake. This is the first time that fiber has been associated with lifetime risk of heart disease.

Donald M. Lloyd-Jones, M.D., corresponding author of the study and chair of the department of preventive medicine at Northwestern University Feinberg School of Medicine and a cardiologist at Northwestern Memorial Hospital, commented on the results:

"It's long been known that high-fiber diets can help people lose weight, lower cholesterol and improve hypertension. The results of this study make a lot of sense because weight, cholesterol and hypertension are major determinants of your long-term risk for cardiovascular disease."

However, he warns that people should try to get this daily fiber intake from whole foods, not processed fiber bars, supplements and drinks. He said:

"A processed food may be high in fiber, but it also tends to be pretty high in sodium and likely higher in calories than an apple, for example, which provides the same amount of fiber."