Fun With Fiber: The Real Scoop

One of our most cherished pleasures in life happens to be challenging conventional wisdom (CW). You never would’ve guessed, right? After all the talk of meat and fat this week, we’ve been feeling, well, rather off. We figured it was the perfect time to take on everyone’s favorite gristly subject: fiber.

CW says Americans need serious fiber in their diets. And by “fiber” CW often means bran buds, whole wheat, psyllium husks – you know, sticks and twigs roughage. We’re talking that 1980’s Saturday Night Live bit about Super Colon Blow cereal. Let’s just say that the more sensitive among us, in particular, want to broach the question: “Is this really the best way?”

So, we thought we’d do some digging. Our ventures into the bowels of fiber research turned up some stimulating information. (O.K., we’ll stop.) First, let’s sit back and enjoy a brief gastronomical lesson. Anyone for some popcorn before we start? (Moving on!)

What is the point of fiber anyway? What does it do? Well, on one hand, soluble fiber (vegetables, fruit, oatmeal, and legumes that partially dissolve in water) enhances the thickness of the stomach’s contents. This slows stomach emptying. While this can give the body more time to absorb nutrients, it can also “trap” minerals like calcium or zinc, binding them up in such a way that they don’t have the opportunity to be absorbed. Insoluble fiber (like whole grains, seeds and fruit skins) increases the mass of the stool, which actually moves the stool more quickly through the intestines. Insoluble fibers pass through the digestive system relatively intact. Continuing on…

Let’s explore the reasons we’re supposed to incorporate fiber into our diets and what some sources have to say.

Fiber helps keep you regular
Some of us can reliably mark off our daily calendars, we’re so consistent. Others, well, not so much. For some of us, things come easily. Others, well, we won’t go there.

Whatever the issue, fiber can help, or so says CW. While our personal experiences don’t directly challenge that claim, our research showed a less than comforting picture of the long-term effects.

Some research shows that the very fiber we turn to with perfectly innocent intentions can become a serious monkey on our backs. It turns out, we may have to continually up the ante over time until we’re in over our heads – or behinds, so to speak.

The key to a healthy gastronomical tract is not roughage but bacteria. The large intestine’s natural bacteria, which help comprise stool bulk, maintain water content and soften the stool. (Sounds like those ads, huh?) Fiber, particularly excessive insoluble fiber, offering a quick jump start to things is not the natural catalyst for a healthy excretory system.

Finally, when it comes to long term “issues,” The American College of Gastroenterology Functional Gastrointestinal Disorders Task Force didn’t find fiber to be an effective treatment for chronic constipation.

Fiber lowers cholesterol
We’ve been talking about the cholesterol issue a lot this past week. As you’ve likely read, we believe cholesterol numbers aren’t the secret code to your health or longevity prospects.

Studies, some reliable and some not, have shown relatively minor changes in cholesterol as a result of higher fiber intake. These same changes have not carried over as predictors of heart disease. (I think I hear a broken record.) Furthermore, these “improvements” in cholesterol had a difficult price for some subjects in terms of gastrointestinal troubles.

Fiber lowers your risk of cancer
It’s usually colon cancer that people mean here, and the studies vary much more than you likely hear. The New England Journal of Medicine and The Lancet include studies that show high fiber diets do not lower the risk of cancer or incidence of polyps, a common precursor to cancer.

But maybe we’re onto something…. Some studies, including a study published in the International Journal of Cancer, break down the fiber sources of their subjects. And guess what? Researchers found that vegetable based fiber (as opposed to that from cereal and fruit) was the most cancer protective. The study focused on those with a risk of prostate cancer, but other researchers and physicians extend this claim to suggest a vegetable based high fiber diet in lieu of carbohydrate fiber sources.

Fiber helps prevent and/or treat diabetes
Here we find ourselves back to the question of what kind of fiber. The standard recommendation for diabetics is soluble fiber. A study in the Journal of Clinical Epidemiology found that high vegetable consumption (in this case, raw) was consistent with an 80% lower incidence of Type 2 diabetes. Studies using carbohydrate sources have not shown these kinds of results.

Soluble fiber slows stomach emptying, which prevents the body from being flooded with glucose at the same rate as it would be with a low fiber meal (assuming a high glycemic load in the meal). But therein lies the pertinent question: if you maintain a diet with low glycemic load, do you really need to slow the digestion process with fiber? Hmm. If that fiber were adding a plethora of nutrients, as found in vegetables, then the answer would be yes. But as for a fiber source without all those nutrients? Not so convincing.

We’ll let you take it from here. We hope we’ve given you something interesting to chew on. Send us your perspectives and suggestions on the fiber question.

Peter Guthrie Flickr Photo (CC)

Further Reading:

Sh*t Happens

That’s Fit: Coffee – A Good Source of… Fiber?

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