Different kind of fibers

Fibers can have different properties, such as being soluble, insoluble, and fermentable.

Soluble, insoluble, and fermentable fibers

The difference between soluble and insoluble fibers relates to how they behave in the digestive system. Soluble fibers dissolve in water and are absorbed by the body. Insoluble fibers, on the other hand, retain their structure and are not absorbed by the body. Instead, they exit the body through stool.

Fermentation refers to the process where fibers are broken down by bacteria present in the large intestine. Only soluble fibers can be fermented.

To support normal bowel function, it is important to consume sufficient amounts of the different types of fibers daily.

Soluble fibers

As the name suggests, soluble fibers can dissolve when they come into contact with water. After consuming these fibers, they dissolve as they pass through the digestive system. This property helps slow the absorption of certain nutrients, such as fats and sugars, into the body. Soluble fibers also provide a feeling of fullness, meaning you feel satisfied for longer after eating. This can help in maintaining a healthy body weight. Most soluble fibers are fermented by our gut bacteria. They are not digested but fermented. Fermentation means that they are essentially “eaten” by the gut bacteria, allowing these bacteria in the large intestine to grow. During this process, beneficial substances like short-chain fatty acids are released, which support normal bowel function and stool consistency. When soluble fibers are fermented, they are also known as prebiotic fibers or prebiotics.

Foods rich in soluble fibers include oats, legumes, fruits such as apples and oranges, vegetables like carrots and broccoli, and nuts and seeds like almonds.

Insoluble fibers

Insoluble fibers can be compared to a sponge in how they work. They absorb moisture, increasing the volume of the stool. This helps keep the stool soft and promotes regular bowel movements. They maintain their original form and exit the body in that same form through stool. Insoluble fibers are neither digested nor fermented, but they contribute to regular bowel movements by absorbing moisture and increasing stool volume.

Foods rich in insoluble fibers include whole grain products such as whole wheat bread, whole wheat pasta, and brown rice, as well as certain vegetables like broccoli, Brussels sprouts, and carrots, and fruits such as plums and berries.