According to fiber

According to the source of fiber, dietary fiber can be divided into plant matter and non-plant cell wall: plant matter dietary fiber includes cellulose, hemicellulose, lignin and pectin . Non-plant cell wall dietary fibers include gums, plant mucilages, algal polysaccharides and modified cellulose.

From the perspective of digestion and absorption

From the perspective of digestion and absorption, dietary fiber is divided into two types: soluble and insoluble:

Soluble fibers mainly include mucilage, carrageenan, and hydroxymethylcellulose that turn into gel after absorbing water. This type of dietary fiber is soluble in water and therefore is a digestible and absorbable plant-derived carbohydrate. Their function is to slow down the emptying of food in the stomach and speed up the passage of food through the small intestine. This slow and fast decreases the digestion and absorption rate of nutrients in the food.
Insoluble dietary fiber mainly includes cellulose, hemicellulose and lignin, mainly from whole wheat flour, bran, cereal grains and vegetables. The structure of this type of fiber cannot be broken down by digestive enzymes in the small intestine, so it is not digested and absorbed. Among them, grains and bran have less impact on the digestion and absorption of food nutrients, but they will increase the amount of defecation.

How dietary fiber is digested in the body

Bacteria in the large intestine break down part of the dietary fiber through fermentation to form short-chain fatty acids including acetate, propionate and butyrate. These short-chain fatty acids do not directly participate in the body's energy supply, but provide energy for intestinal epithelial cells and promote the absorption of salt and water in the colon.

The effect of dietary fiber on dogs

Dogs living in the wild generally do not need a large amount of dietary fiber. But for domesticated dogs, dietary fiber has its own special uses, such as promoting bowel movements, increasing satiety and promoting weight loss. The diet of dogs who are losing weight can contain relatively more dietary fiber. These fibers can not only reduce the digestion and absorption rate of nutrients, but also relieve the hunger of dogs who are losing weight.

The important thing to remember is that there is no such thing as too much. Excessive intake of dietary fiber will reduce the digestion and absorption rate of proteins, carbohydrates, and fats, thereby affecting the absorption of some vitamins and minerals, and there is a risk of causing malnutrition in pet dogs. Fermented fiber in excess of requirements produces large amounts of short-chain fatty acids, which can cause diarrhea in pet dogs.

One or more of the above dietary fibers are added to industrially produced dog feed. Fresh food made for dogs using daily human ingredients generally contains no more than 1.4% dietary fiber. If desired, dietary fiber can be increased by adding relatively large amounts of vegetables, legumes, or bran-containing grains.