Making Sense of Fiber: Which is Beneficial?

Most people know that they should consume more fiber in their diet but are not sure how much and which types. Hearing terms like "soluble fiber" and "nonsoluble fiber" makes it even more confusing. Diets high in dietary finer have been shown to reduce the risk of developing chronic and debilitating diseases like cardiovascular disease, type 2 diabetes and certain types of cancer. An article published in the American Journal of Clinical Nutrition (2005;82(6):1185-1194) examined the effects of different types and sources of fiber on risk factors of cardiovascular disease (CVD).

In the study, nearly 6000 men and women provided dietary records and blood samples to measure various CVD risk factors, as well as submitting to clinical evaluations including measurement of blood pressure and hip to waist ratios. Researchers discovered that the individuals consuming the highest levels of total dietary fiber and nonsoluble dietary fiber had the lowest risk factors for cardiovascular disease, such as elevated blood pressure and hip to waist ratio, overweight, cholesterol, triglycerides and homocysteine. The best example of insoluble fiber is wheat bran which is high in cellulose, a plant material that cannot be fully digested by humans, resulting in improved bowel movements. Soluble fiber (like pectin, gums and mucilages) also exerted positive effects, although not as profound as nonsoluble fiber. Effects of specific fiber sources were also evaluated, demonstrating:

(1) cereal fibers lowering body mass index, blood pressure, and homocysteine concentration

(2) fiber from vegetables can lower blood pressure and homocysteine concentration

(3) fruit fiber lowers waist-to-hip ratio and blood pressure

(4) fiber from dried fruit or nuts and seeds lowers body mass index, waist-to-hip ratio, and fasting apo B and glucose concentrations

Based on these findings physicians may be able to tailor fiber recommendations specific to individuals and their disorders. Overall, total daily fiber intake should be at least 30-35g. Many cultures consume more than 100g of fiber per day and experience much lower rates of colon cancer and cardiovascular disease than Western societies.