Dietary Fiber
Dietary Fiber Cheat Sheet
For many of us, thinking about dietary fiber is about as exciting as watching paint dry. However, the consequences of an inadequate intake of dietary fiber can be serious. Studies suggest that most of us fail to consume the recommended amount of dietary fiber or what’s commonly referred to as “roughage” in our diets. Many people simply lack an understanding of the importance of dietary fiber, how much they actually need to consume per day, or what the difference between soluble and insoluble fiber.
Dietary fiber is a relatively broad term that includes many plant components that share the characteristics of being indigestible. This means that dietary fiber is not digested, absorbed by the body , or used for energy. There are two main sources of dietary fiber–soluble fiber and insoluble fiber. *Note many plant sources include both soluble and insoluble fiber.
Insoluble fiber does not dissolve in water and does not get broken down by bacteria in the intestine. Instead, it essentially absorbs water to help to increase bulk and to soften stool. The net effect of insoluble fiber is that it promotes regular bowel movements. Additionally, insoluble fiber helps us to feel full which may reduce obesity. It also may reduce our risk of developing hemorrhoids.
Food sources of insoluble fiber include: whole-wheat products, corn bran, brown rice, and certain vegetables such as carrots, celery, and tomatoes.
Soluble Fiber differs from insoluble fiber in that it dissolves in water and additionally is broken down by bacteria in the intestine. Soluble fiber helps prevent cholesterol from being absorbed by the intestines and is thought to help minimize the rise in blood sugar following a meal.
Sources of soluble fiber include: oatmeal, bean, fruits (apples, plums, kiwi, pears, blackberries, strawberries, raspberries, peaches, citrus fruits, dried apricots, prunes, and figs), as well as some some vegetables (dried peas, beans, and lentils).
To reiterate, fiber has is a salubrious component of our diet with several potential health benefits inculding:
- Helps prevent constipation
- May reduce risk of colon cancer
- May reduce LDL cholesterol and cardiovascular risk
- May reduce the risk of developing type 2 diabetes
- Helps to increase satiety and reduce caloric intake
With respect to the question of how much fiber you actually need per day, the ‘new’ guidelins suggest that women require 25 g per day while men should consume 38 g per day.
How much of each type do you need? It really doesn’t matter so much, both types are important, just try to consume more fiber!
Is it better to consume fiber in supplements or from food sources? “Few fiber supplements have been studied for physiological effectiveness, so the best advice is to consume fiber in foods.” (Slavin et al, 2008).
References:
Bazzano LA. Effects of soluble dietary fiber on low-density lipoprotein cholesterol and coronary heart disease risk. Curr Atheroscler Rep. 2008 Dec;10(6):473-7.
Slavin JL. Position of the American Dietetic Association: health implications of dietary fiber. J Am Diet Assoc. 2008 Oct;108(10):1716-31.
About the Author
Dr. Morrow received his Doctor of Medicine from The University of Alberta in June 2001 and prior to that, received his Bachelor of Science with Specialization in Pharmacology with Distinction, also from The University of Alberta, in June 1997.
Dr. Morrow has been a distinguished presenter at numerous scientific and medical conferences worldwide, generally involving various areas of psychiatry, including anxiety disorders and the physical impact of psychological stress, and has also co-authored numerous medical research publications generally involving similar subjects. Dr. Morrow is a member of American Mensa.
Good to Know about Dietary Fiber