Fiber is a carbohydrate and is usually listed under “Total Carbohydrates” on the “Nutrition Facts” label. Humans lack the digestive enzymes to breakdown fiber. Therefore, it is undigested and not absorbed into the bloodstream and it arrives at the colon pretty much intact. Fiber has zero calories. Instead of being used for energy, it is excreted from the body.
The current recommended daily intake for adults who are 50 years or younger is 25 grams/day for women and 38 grams/day for men. For adults over 50 years of age, the recommendation is 21 grams/day for women and 30 grams/day for men. Unfortunately, for many who eat a typical American diet, it can be a huge challenge to consume that much fiber everyday. Most people top out at an average of 15 grams/day, regardless of how many calories they eat.
Maybe if we understand more about the different types of fiber and how they can immensely contribute to better health and lower disease risks, there will be more incentives to increase the daily fiber intake. Fiber is an important part of a healthy, balanced diet. Apart from helping us stay regular, fiber has a long list of other health benefits. The following will distinguish the different types of fiber, their specific health advantages, and which foods contain these fiber.
Classifications Of Fiber
There are several ways to classify the different types of fiber. However, as their characteristics do overlap, experts have yet to agree on the best categorization. For decades, the most commonly used classification is soluble and insoluble fiber. These days, as researchers discover the benefits of fermented fiber, another classification – fermentable and non-fermentable fiber – is also used. However, do know that both soluble and insoluble fiber have some that are fermentable and some that are non-fermentable, though soluble fiber is more easily fermented.
Soluble and Insoluble Fiber
The major difference between soluble and insoluble fiber is that they have different properties when mixed with water, hence the designation between the two.
- Soluble fiber is soluble in water. When mixed with water, it forms a gel and swells.
- Insoluble fiber does not absorb or dissolve in water. It passes through the digestive system in close to its original form.
Both types of fiber serve their own purposes and have different health benefits. Most plant foods contain both soluble and insoluble fiber, just in different proportions. For instance, wheat is about 90% insoluble fiber. Oats are 50/50. Psyllium plant is mostly soluble fiber.
Fermentable and Non-Fermentable Fiber
Some fibers are readily fermented by bacteria that colonize the colon, others are not. Fermentable fiber is used by the colon’s friendly bacteria as a food source. Fermentation results in the formation of short-chain fatty acids (acetate, butyrate, and propionate) and gases. Epithelial cells that line the colon use butyrate as the main source of energy.
Researchers found that butyrate exerts a wide range of health benefits. It:
- Decreases inflammation and oxidative stress,
- Prevents colon cancer, irritable bowel syndrome (IBS), and Crohn’s disease,
- Strengthens the bowel wall,
- Improves the body’s ability to absorb essential nutrients such as calcium,
- Makes hormones that control appetite and anxiety.