Do We Need So Much Fiber? by Dana Carpender

Do We Need So Much Fiber?

For quite some time now I have made a name and a some-time living as a nutritional heretic. I don’t believe in a “balanced diet,” I think animal fat and cholesterol are among the most healthful foods, I consider fruit juice to be little better than soda pop, I’m all for cutting whole categories of food out of my diet. Here’s my latest heresy: I am unconvinced of the value of fiber.

I can hear the collective gasp right through the fiber optics cable. But… but… we need lots of fiber! We need 25 grams a day! It prevents colon cancer! It lowers blood sugar! It’s one of the healthiest things we can eat! If we’re not getting enough fiber through our food, we need to take fiber supplements! How else will we stay, er, regular?

Uh-huh. Uh-huh. Yeah, heard it before. Even believed it for quite a while. Now? Not so much.

Oh, I have nothing against fiber. I’m just unconvinced that in and of itself it does much. If my suspicion is correct, and fiber is not important, why all those studies showing that fiber does so many great things?

It’s a matter of context. After all, what foods contain fiber? Why, plant foods, of course. So people who get a lot of fiber – without taking supplements – are eating a lot of plant foods.

This may well mean that they’re eating a lot of vegetables. I trust we’re all clear on the value of eating our vegetables? Fiber that comes from vegetables is accompanied by vitamins, minerals, and various interesting antioxidants and phytochemicals. It is possible that those are the beneficial substances, rather than the fiber, no?

Fruit is also a decent source of fiber, vitamins and antioxidants. It is also a source of sugar. Take the fiber out of fruit and what do you have? Juice. And juice is a great way to take in a whole lot of sugar. Could it be that the benefit of eating the whole fruit instead of drinking juice lies in the reduced sugar load?

Nuts and seeds are yet another great source of fiber. They’re also loaded with minerals and healthy fats, and some, like flax seeds, also have a lot of antioxidants. Again, does the benefit come from the fiber, or the stuff that comes along with it?

Whole grains have more fiber than refined grains, though they’re not the great source of fiber officialdom makes them out to be. (A half-cup serving of brown rice has a big 2 grams of fiber. I can get that much fiber from 4 calories worth of romaine lettuce.) They also have a far wider array of nutrients than refined grains. Again, what is improving health, the fiber or the vitamins?

Too, when fiber is combined with carbohydrate it slows the absorption of that carbohydrate into the bloodstream, lessening the glycemic impact of whatever food has been eaten. This means that higher fiber carbs are, in general, gentler on blood sugar than low fiber carbs, when taken gram-for-carbohydrate-gram. Too, since fiber is neither digested nor absorbed, it dilutes the digestible carbohydrates in any food it is in, cutting the number of absorbable grams of carb. These are all good things, but again, this is not evidence that fiber in and of itself is valuable. If you’re not eating a lot of carbs, period, your blood sugar will be stable regardless of how much fiber you consume.

See, that’s the thing: So far as I can tell, it’s not about the fiber, it’s about what’s eaten along with it.

What about bowel function? Surely we need fiber for proper bowel function. I don’t know. I mean, sure, your average American can become darned constipated without plenty of fiber. But then, your average American is also eating a ton of starch. You know what another name for starch is? Paste. (Wallpaper paste was made of starch for centuries. What do you think the word “pasta” means? Or “pastry?”) When you’re living on a diet of paste, it’s not too surprising that you get clogged up.

But what if you don’t eat paste? What if you eat meat, vegetables, nuts and seeds? Do you need a ton of fiber to get that through you? Or will a paste-free diet move along pretty well on its own? That’s probably an individual thing, but I know from years of talking to low carbers that a whole lot of us have no problems along that line. (Do you have any idea how hard it is to talk about this and not be vulgar? Geez.) But absent a steady diet of paste, I see no reason why 25 grams of fiber per day should be needed.

(This might be a good place to mention yet again that there have been at least a few societies that ate very, very low carbohydrate diets, nearly devoid of plant matter, and thrived on them. The Eskimo are the example everyone cites, but the Masai of Africa also ate a diet based almost entirely on animal foods, in their case raw milk mixed with cow’s blood. Yecch, I know, but it was apparently a very healthful diet – and had very little fiber.)

By the way, it’s beginning to appear that what wheat bran does to stimulate the bowels is to scratch the intestinal wall – actually scours it. The intestine, trying to protect itself, secretes mucous, thus making the walls of the intestine slippery. I’m not sure this sounds like a great thing. Fiber-based laxatives, by contrast, are made of soluble fiber, usually psyllium; they mostly work by absorbing water, creating a soft, bulky mass that moves easily. And that’s quite enough of that mental image.

All of which may explain why studies trying to link high fiber consumption with lower rates of colon cancer keep coming up short:

• Fiber Does Not Help Prevent Colon Cancer, Study Finds
• Dietary fiber intake and risk of colorectal cancer: a pooled analysis of prospective cohort studies. (read the very last sentence)
• Dietary fiber and whole-grain consumption in relation to colorectal cancer in the NIH-AARP Diet and Health Study.

I don’t have anything against fiber, mind you. I’m perfectly happy to use high-fiber ingredients like flax meal, almond meal, coconut flour, oat bran, and the like in my low carb baked goods; they’re great, nutritious, good-tasting substitutes for all that paste, and they sure are easy on the blood sugar. And I love vegetables, have been eating a ton of strawberries over the summer, and eat nuts and seeds often.

But I don’t sweat my fiber intake. If I don’t get the government-recommended 25 grams of fiber per day, I don’t worry about it. I really don’t even pay attention, except when doing the total carbohydrate – fiber equation to figure out my net carbs.

As for all the fiber-fortified junk food on the market? Fiber candy bars and fiber cereals and fiber-fortified sweetened yogurt and the like? I consider them worse than useless, since they contain substantial quantities of cheap digestible carbohydrate.

If you are prone to constipation, go ahead and add some flax or chia seed to your diet, and eat a lot of vegetables. Or if you like, take a sugar-free psyllium laxative. Other than that? So long as you’re eating low carb, fiber looks like just one less thing you need to worry about.

© 2009 by Dana Carpender. Used by kind permission of our “regular” low carb author. What do you think? Please send Dana your comments to Dana Carpender.