The Role of Fiber in Human Health

The Role of Fiber in Human Health

Nutritionists have been clamoring for years about the importance of adequate fiber intake, but advice to eat fiber often runs through us like fiber itself: undigested. With a better understanding of the role of fiber in human health, perhaps we can begin (or continue more confidently) to adjust our diets to include proper types and amounts of fiber.

Put simply, fiber is an edible, non-digestible type of carbohydrate. Fiber is not digested because mammals lack enzymes capable of digesting it. So instead of being broken down and absorbed in the small intestine, fiber passes into the large intestine more or less intact. This is great news for the trillions of bacterial cells that comprise the microbiome in our gut, as they ferment and feed on this undigested material.

This process is crucial because our relationship with the bacteria in our gut is a symbiotic one: in exchange for hosting them, they provide us with an array of health benefits. We’ll dial in on these health benefits in a future article analyzing gut health, but for now suffice it to say that humans rely on these bacteria to function optimally. So by eating the right types of fibers, we maintain a healthy, diverse microbiome, and enjoy the resulting health benefits.

Some fibers dissolve in water (soluble), while others do not (insoluble). Soluble fibers, such as those found in seeds, nuts, beans, oat bran, apples, and blueberries, have been linked to lower levels of glucose and blood cholesterol in humans. Insoluble fibers, such as wheat bran, brown rice, carrots, and cucumbers, help prevent constipation.

Fibers may also be classified as dietary or functional. Dietary refers to fiber found in foods naturally; and functional refers to fiber isolated and added to processed foods. A great deal of research focuses on dietary fibers, and this is often what you will see listed on your food’s nutrition label, so it is important to understand that many plants containing dietary fibers also carry with them a range of other nutrients. This makes a difficult task of attributing the health benefits to dietary fiber, or the peripheral nutrients those plants contain.

In any case, the studies linking dietary fiber intake to health benefits are manyfold. In addition to enhancing gut health, diets with high intakes of fiber correlate with significantly lower risks of coronary heart disease and metabolic syndrome. Other studies have linked low-fiber diets to type 2 diabetes, while high-fiber diets have been associated with lower risks of diverticular disease and constipation.

While there is conflicting information correlating high-fiber diets with lower risk of colon cancer, studies show a link between high fiber intake and reduced risk of breast cancer.

So how do we ensure eat enough fiber? For one, try to replace white grain items (rice, bread, pasta) with whole grain foods; replace fruit juices with whole fruits; replace sugary cereals with a breakfast high in whole grain, such as wheat bran; and try beans and legumes in lieu of red meat.

Of course, everyone is different, so you will want to consult with your doctor. If you do increase fiber intake, do so gradually and while drinking lots of water, as fiber absorbs water in the digestive tract.

Oh and btw, SaladPower is an excellent source of fiber!

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