Fiber Made Simple

by John Meadows, CSCS – 8/11/2011

Let's talk fiber. Do we really need as much as doctors claim? If so, how much? Can we get too much? Will it prevent cancer? Are grass-fed steak and whole eggs good sources of fiber? How the heck do I get rid of this constipation?

This is just a sampling of the many questions I get regarding dietary fiber.

What is Dietary Fiber?

Fiber is a complex carbohydrate made up of non-starch polysaccharides, resistant starches, and/or cellulose. In simple terms, when you hear fiber, think plants, namely veggies, fruits, and whole grains. Just as we have cells that give our body structure, so do plants. (Don't eat humans, though. They don't provide fiber.) These plant cells can hold nutrients, water, and other things. There are essentially two kinds of fiber. Each is unique, and possesses specific beneficial qualities.


Soluble Fiber


This type is very resistant to breakdown by the digestive enzymes in your mouth, stomach, and small intestine. Gums, pectins, and inulin are in this category.

Gums stabilize food, giving it more of a shelf life. They also add texture to food. Probably most importantly, they slow down the absorption of glucose.

Pectins are a little different in structure than gums. They're more acidic, aiding in the absorption of certain minerals like zinc. Similar to gums, they also lower blood sugar levels. Probably the most well known source of pectin is apples. They're the source for many commercial pectin formulations.

Inulin is a FOS, or fructooligosaccharide. If you read my article on digestion you'd know that inulin is a pre-biotic that feeds the good bacteria in your stomach. When I noticed this was in Metabolic Drive® Muscle Growth, I did cartwheels (figuratively, of course). When you see foods containing FOS in the chart below, take note.

You'll generally find soluble fiber in fruits, beans, barley, oats, and some other sources. It does get digested – sort of – but not until it hits the large intestine, where good bacteria ferment it, producing butyric acid (found in butter) and acetic acid (found in vinegar). This helps the digestive system maintain its acidity.

Some soluble fibers provide a bit of energy, about two calories per gram; likely not enough to get you through a particularly harsh drop-set on the leg press. Others such as gums are non-caloric.

So what are the key benefits to soluble fiber? There are three that warrant attention.


Three Key Benefits of Soluble Fiber
Stabilizes blood sugar. Soluble fiber slows down transit time (the time it takes for food to enter and leave the body) and encourages a more gradual breakdown of food. Specifically, it slows down the emptying of the stomach and the digestion of starches (and subsequent entry of glucose into the blood stream). Since glucose absorption will be slower, you can avoid the blood sugar ups and downs.

I've even heard of people mixing guar gum with water before meals to accomplish this. If you're a diabetic, you should consider this before you opt to skip the veggies. Eating your veggies could mean you'll need less insulin.

Lower LDL levels. When short chain fatty acids are made as a result of the fermentation of soluble fiber, it appears to result in a decrease in LDL levels. Good news for those concerned about cardiovascular disease.

Increased defense against cancer. Fiber can bind with cancer-producing compounds and remove them from the body, rather than letting them hang around to wreak havoc. Also, as fiber is fermented into short chain fats like acetic acid in your intestine, it helps the colon maintain its pathogen-killing acidity.


Insoluble Fiber


This type of fiber doesn't get digested anywhere. It's essentially lignin, cellulose, or hemicellulose, and you'll typically find it in wheat or veggies. Its job is to simply carry food and water through the digestive system.

Unlike soluble fiber, insoluble fiber doesn't dissolve in water. This means that it swells up like a sponge, and adds bulk to the stool. This makes your feces move faster through your intestines (called intestinal hurry). There are several key benefits to insoluble fiber.