Food companies often tout the benefits of “added fiber” in their products. As it turns out, that “added fiber” may be keeping you overweight and sick.
As a result of a fire code issue at an old office of mine, we had to cut our desks down a foot to allow wider walkways. As we were modifying desks (read: thrashing with a circular saw), we produced quite a bit of sawdust, which we collected on paper plates (we didn’t have a dustpan at this point).
As lunch time rolled around, jokes (everyone was kidding, right?) abounded about adding the sawdust to our meal to “make sure we got our fiber in.”
We were kidding, but processed food giants really do put wood pulp and the like in some of their products. Yuck.
Industrial food production methods aside, what is the deal with fiber? Do we need it? Is it healthy? Should we eat our desks?
A few years ago, Dr. Michael Eades published an illuminating article on all things fiber. Let’s take a look at the key points.
It’s well worth a read, you should click over – if for nothing more than his insightful comparison of cigarettes and mucus production to fiber and bowel movements.
Just like cigarettes increase mucus production by damaging the lining of your airways, fiber promotes “regularity” by damaging the lining of your intestinal tract. As explained by Dr. Paul McNeil:
When you eat high-fiber foods, they bang up against the cells lining the gastrointestinal tract, rupturing their outer covering. What we are saying is this banging and tearing increases the level of lubricating mucus. It’s a good thing. These cells are a biological boundary that separates the inside world, if you will, from this nasty outside world. On the cellular scale, roughage, such as grains and fibers that can’t be completely digested, are a mechanical challenge for these cells. But in what he and colleague Dr. Katsuya Miyake view as an adaptive response, most of these cells rapidly repair damage and, in the process, excrete even more mucus, which provides a bit of cell protection as it eases food down the GI tract.
As Dr. Eades points out, Dr. McNeil is making a critical error. He starts with the flawed assumptions that (1) everyone needs to poop more for some reason and (2) damaging the epithelial cells of your intestinal lining causes no ill-effects. Another quote reveals the truth:
The scientists aren’t certain how many times cells can take a hit, but they suspect turnover is so high because of the constant injury. Potentially caustic substances, such as alcohol and aspirin, can produce so much damage that natural recovery mechanisms can’t keep up.
Fiber is recommended because it damages your gut lining – yet damaging these cells may be a bad thing (ya think?).
I should note that a critical distinction exists here that we have yet to discuss; insoluble vs. soluble fiber. Thus far, we’ve been discussing insoluble fiber, which acts on your digestive tract in a purely mechanical way. It is indigestible, and serves to do little but damage your gut lining. Soluble fiber (like that found in the skin of apples), however, is your friend. Assuming a healthy gut biome, this type of fiber is digested by resident bacteria, yielding butyric acid (a saturated fat) as energy. It’s true – when you eat berries, apples, etc, you’re getting some calories in the form of saturated fat.
In Myths and Truths About Fiber, Chris Kresser explains the effect that insoluble fiber exerts on your gut bacteria:
In fact, many studies have demonstrated that excess intake of fiber may actually be harmful, particularly for gut health. Tan and Seow-Choen, in their 2007 editorial on fiber and colorectal disease, call insoluble fiber “the ultimate junk food”, as “it is neither digestible nor absorbable and therefore devoid of nutrition.” Excess insoluble fiber can bind to minerals such as zinc, magnesium, calcium, and iron, preventing the absorption of these vital nutrients. Large excesses of certain soluble fibers like pectin and guar may also inhibit pancreatic enzyme activity and protein digestion in the gut, leading to an anti-nutritive effect.
The addition of insoluble and soluble fibers to processed foods may actually cause these foods to be even less nutritious.
In light of everything we’ve discussed here, I’ll continue to skip “fiber-enriched” processed foods in favor of real, whole foods – and I suggest you do the same.