Is ‘soluble fiber’ really fiber?
John Swain, Globe Correspondent / Sep 13, 2010
I often see commercials on TV talking about
soluble fiber. If it dissolves, it can’t be fiber, can it?
Fiber, or roughage as it used to be called, is basically the part of a plant your body can’t digest. Think of chewing celery: Eventually, you’ll have a wad of fibers small enough to swallow, but they don’t break down into anything digestible. That stuff will make it all the way through your digestive tract intact.
Insoluble fiber is basically cellulose and related materials made largely of chains of sugars. Humans can’t digest it, but termites have microbes in their guts that digest cellulose for them, which is why they can derive nourishment from eating wood.
Another form of fiber, soluble fiber, is also made of parts of plants your body can’t digest, but which, unlike cellulose, can dissolve in water.
While not technically digestible, soluble fiber can ferment in your colon because of microorganisms that live there, and your body can use what is produced — sort of the human equivalent of termites having microbes that allow them to eat wood. This is also part of why antibiotics can wreak havoc with your digestive tract, since they can kill helpful bugs.
Both types of fiber are important in your diet, and you can be sure to get them by eating a variety of plants.
Fiber can bind bile acids, preventing them from getting back into the body and thereby reducing cholesterol levels, and its presence can slow the absorption of sugars, which is good for diabetics and aids weight loss.
Fermentation of soluble fiber produces short-chain fatty acids, which can do all sorts of good things for you, including improving absorption of nutrients.
Ask Dr. Knowledge is written by Northeastern University physicist John Swain. E-mail questions to firstname.lastname@example.org or write to Dr. Knowledge, c/o The Boston Globe, PO Box 55819, Boston, MA 02205-5819.
Dx'd with moderate Pancolits 05/07 better with Pentasa and rectal meds as needed.
I also take Probiotics, Fish Oil, Curcumin, Benefiber and cannot tolerate artificial sweetners (never could even before UC) I also stay away from products with high fructose corn syrup.
UC Forum Co-Moderator
I am not a healthcare provider. I am offering support and guidance based upon my own conclusions and/or research. ALWAYS consult with a qualified healthcare provider.