Soluble and insoluble fiber: Differences and benefits
Dietary fiber, the indigestible part of plant material, is made up of two main types. Soluble fiber easily dissolves in water and is broken down into a gel-like substance in the part of the gut known as the colon. Insoluble fiber does not dissolve in water and is left intact as food moves through the gastrointestinal tract.
The term fiber refers to all the parts of plant-based foods that cannot be digested or absorbed by the body. Unlike simple carbohydrates, including most breads and sugars, fiber is a complex carbohydrate and does not raise blood sugar levels.
Fiber is commonly found in vegetables, fruits, whole grains, and legumes. It is also sometimes called roughage or bulk. It is an essential nutrient, which means it must be eaten in the diet.
Fast facts on soluble and insoluble fiber:
Soluble and insoluble are the two main types of fiber. Many fiber-rich foods contain some of both.
Both forms of fiber have health benefits.
Humans have been using fiber as a dietary aid since ancient times.
In a society built on refined carbohydrates, or white breads, pastas, and sugar sweeteners, getting enough fiber can take effort.
Soluble versus insoluble fiber
Whole grains and cereals are a good source of fiber, particularly insoluble fiber.
Soluble fiber dissolves in water and gastrointestinal fluids when it enters the stomach and intestines. It is transformed into a gel-like substance, which is digested by bacteria in the large intestine, releasing gases and a few calories.
Insoluble fiber does not dissolve in water or gastrointestinal fluids and remains more or less unchanged as it moves through the digestive tract. Because it is not digested at all, insoluble fiber is not a source of calories.
Benefits of fiber
The health benefits of dietary fiber are plentiful. Some of the main ones are listed here.
Lowering fat absorption and helping weight management: As a thick, spread-out gel, soluble fiber blocks fats that would otherwise be digested and absorbed.
Lowering cholesterol: Soluble fiber prevents some dietary cholesterol from being broken down and digested. Over time, soluble fiber can help lower cholesterol levels or the amount of free cholesterol in the blood.
Stabilizing blood sugar (glucose) levels: Just as it prevents fats from being absorbed, soluble fiber slows down the digestion rate of other nutrients, including carbohydrates. This means meals containing soluble fiber are less likely to cause sharp spikes in blood sugar levels and may prevent them.
Reducing the risk of cardiovascular disease: By lowering cholesterol levels, stabilizing blood sugars, and decreasing fat absorption, regularly eating soluble fiber may reduce the risk of heart disease and circulatory conditions.
Feeding healthy gut bacteria: Some soluble fiber-rich foods feed gut bacteria, as it is fermentable in the colon, and so it helps the bacteria thrive longer.