Which type of fiber is fermented by bacteria in the large intestine?

Soluble fiber is the type of fiber that is fermented by bacteria in the large intestine. This fermentation process occurs when soluble fiber is broken down by gut bacteria, producing short-chain fatty acids and gases as byproducts. Soluble fiber is known for its ability to dissolve in water, forming a gel-like substance that can help slow digestion and control blood sugar levels. It is found in foods such as oats, beans, lentils, apples, and citrus fruits.

In contrast, insoluble fiber does not dissolve in water and passes through the digestive system largely intact. Its primary function is to add bulk to the stool and facilitate regular bowel movements. While both dietary and functional fibers can include components of soluble and insoluble fibers, the focus on fermentation specifically pertains to the soluble variety.