We should all try to get more fiber into our diets. Dietary advice like this falls into the “duh!” category along with drinking more water and eating your greens. We all know it’s important, but why? In reality, fiber is much more complex than simply 'fiber', as you quickly discover. Each type has a different effect, and they come from a variety of sources. How
much? What type?
The “why” of fiber is the simplest answer. Fiber helps your digestive system work properly, which resolves a number of other problems. A dysfunction in the gut can cause chronic degenerative diseases such as autoimmune disease, osteoarthritis, diabetes, or cancer. When fiber is combined with adequate water, it gives bulk to your stool, which drives the movement of stuff through your bowels. Toxins are eliminated through the stool, so it shouldn't be kept too long. We also don't want to lose water and nutrients by going too fast. We want a balance of fiber, water, food, and bacteria to digest, ferment, absorb, and eliminate.
Wait, what? Ferment? That’s how beer is made. Yes, but fermentation is also how the gut bacteria function. Fiber comes in two basic types, soluble and insoluble (in water), neither of which is digestible by our guts, but has to be processed by our intestinal flora. We have developed a symbiotic relationship with our gut flora, we give them a home and food, and they ferment fiber to produce Short Chain Fatty Acids (SCFAs) and other nutrients. SCFAs are food both for the bacteria and for us. As we learn more about bacteria every day, they also produce vitamins, maintain pH levels, control bad bacteria, and do a host of other things.
About half of the fiber we eat is fermented by bacteria. Depending on the type, the rest performs different tasks. There will be a bulk increase in the stool as well as a stimulation of enzyme production with both types. Moreover, both types delay gastric (stomach) emptying, which aids digestion and moderates blood sugar levels. Insoluble fiber (cellulose) stays mostly in this realm.
As far as soluble fiber is concerned, it is a bit more complex. Soluble fiber can be hemicellulose, mucilage, gums, pectin or fiber compounds. Oat bran is the best example of hemicellulose, and has been shown to lower cholesterol levels. Mucilage is found in the inner parts of seeds, nuts and beans, and will form a thick gel in water. In addition to increasing satiety, the gel also slows sugar absorption, which is beneficial in treating diabetes. A gum is a resin that comes from a plant. Pectin comes from fruits and vegetables' skins. Many soluble fibers bind with cholesterol and can help maintain healthy cholesterol levels. Your doctor may recommend specific fiber supplements for treating different conditions.
Fortunately, eating fiber as a healthy food doesn't require a full understanding of its benefits. Most plants mix both types of fiber. Consume a variety of plant-based foods. Starchy staples (whole grains) with a variety of tubers, vegetables, fruit, legumes, nuts, and seeds have historically provided the best results. Evidence suggests that our ancestors ate 100-150 grams of fiber per day—that's a lot! For modern people, 35-50 grams a day is a great target number to discover the health benefits of this essential nutrient.
