This increases the number and balance of friendly gut bacteria, which also produce short-chain fatty acids with powerful health benefits ( 15). These are fibers that the friendly gut bacteria are able to digest (ferment) and use as fuel ( 14). This is where fermentable fiber comes into play. They are so important that they are often referred to as the “forgotten organ” ( 13).īecause humans can’t digest fiber, it ends up reaching the large intestine mostly unchanged. They play various roles related to weight management, blood sugar control, immunity, brain function and mental health ( 7, 8, 9, 10, 11, 12). These bacteria are actually crucial for optimal health in humans. They are often classified as either dietary (found naturally) or functional (added to foods).Īn estimated 100 trillion live bacteria reside in the human gut, mainly in the large intestine ( 6). Bottom Line:įibers are indigestible carbohydrates found naturally in plant foods. Then there is yet another class of nutrients called resistant starches, which are often classified as dietary fibers. It tells us absolutely nothing about their health effects.Ī popular alternative method is to classify fiber based on its solubility (soluble vs insoluble), viscosity (viscous vs non-viscous) and fermentability (fermentable vs non-fermentable). However, there is a major problem with classifying fiber in this way. Functional fiber: Fiber that is extracted and isolated from whole foods, then added to processed foods.Dietary fiber: Fiber found naturally in foods.The problem is that they are often classified in different ways, which can be highly confusing.įiber is formally classified into two main types ( 3): There is actually a huge variety of different fibers found in foods. However, most people are only eating around half of that, or 15-17 grams per day ( 1, 2).įiber is mostly found in plant foods, including vegetables, fruits, legumes, whole grains, nuts and seeds (for more details, here is a list of 22 high-fiber foods). The recommended intake is 38 grams for men, and 25 grams for women. We lack the digestive enzymes required to break them down, so they pass through most of the digestive system unchanged. “Fiber” refers to a diverse group of carbohydrates that humans can not digest.

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