Five More Fibs About Fiber

Well, if fiber doesn't protect against cancer, it at least protects against heart disease, right?

6. Fiber lowers cholesterol levels and prevents heart disease.

One clinical trial put volunteers on a low-fat diet coupled with the use of a dietary supplement containing corn bran, pea fiber, guar gum, pectin, and soy fiber. At the end of a 105-day trial, the researchers found that LDL ("bad") cholesterol levels had dropped about 8 percent.

But that's not necessarily a good thing.

And whether it's the fiber that is causing the lowering of cholesterol or the other components of your diet is an open question. When you cut back on either fat in your diet or excess calories in your diet, your liver makes fewer bile salts. And the way fiber would lower your cholesterol levels is by capturing bile salts, which are made from cholesterol, so they are flushed down the toilet. But if your liver isn't making the bile salts, fiber isn't capturing them. It's the reduction of fat and calories that make the difference, not the fiber.

7. Fiber fills you up.

Fiber absorbs water. Wet fiber fills your stomach, so you don't get hungry as fast. However, eating fiber on a regular basis expands your stomach, so that when you don't eat fiber, you want more of other foods, like Cheetos, Twinkies, cheeseburgers, and bacon. The benefits of fiber are temporary, but the side effects of fiber are permanent.

8. Fiber prevents gallstones.

Gallstones form when bile salts can't pass of the liver through the bile duct into the gallbladder and on to the gut. When the bile can't flow, crystals of cholesterol and minerals accumulate into painful stones. But what would keep bile from its natural flow into the intestines? Fiber, of course. Too much fiber in the stool keeps the bile from flowing and causes crystals to form.

9. Fiber prevents diarrhea.

Fiber absorbs water, the reasoning goes, and diarrhea is caused by too much water in the contents of the colon, so fiber would slow down the passage of fecal matter and prevent diarrhea. And small amounts of fiber sometimes do exactly this — but that's not necessarily a good thing. Diarrhea is your body's way of getting rid of a toxin, a parasite, or an infection. Stopping diarrhea can prolong an illness.

And soluble fiber, which shows up in foods in which one would not expect it, can actually cause diarrhea, since soluble fiber "slips" through the colon quickly. Disguised as agar, algae, alginates, beta-glucan, cellulose gums, carrageen, fructooligosaccharides (FOS), guar gum, guaran, hemicellulose, Irish moss, Irish algae, kelp, lignins, mucilage, pectin, oligofructose, polydextrose, polylos, resistant starch, resistant dextrin, and kelp extracts, soluble fiber is found in yogurt, ice cream, cream cheese, canned food, jellies, jams, frozen dinners, sour cream, non-dairy creamers, frozen dinners, and prepared foods served in restaurant chains, any time a food needs to be "creamier" without cream. Eating the soluble fiber hidden in these foods can actually cause diarrhea.

10. Eating 9 or 10 pieces of fruit a day will keep you regular.

It's undoubtedly true that eating 9 or 10 pieces of fruit will increase your daily trips to the bathroom (unless you happen to eat an extremely high-fiber fruit like persimmons, which can cause the formation of a bezoar, the human equivalent of a hairball, which can cause severe constipation).

However, not all the sugars found in certain kinds of fruit, especially apples and pears, are completely digestible by human digestive enzymes, so they become food for fermentative bacteria. These bacteria release gas in between your trips to the toilet.

Everything about fiber isn't bad. Everybody needs some fiber every day. Specifically, men need around 30 to 38 grams of fiber a day, while women should go for 21 to 25 grams. But eating massive amounts of plant foods just for the fiber isn't healthy. Five to nine servings of plant foods every day really is enough.