Dietary fiber mainly includes water-soluble dietary fiber, such as gum; non-water-soluble dietary fiber such as lignin. Dietary fiber can be divided into two basic types, water-soluble dietary fiber and non-water-soluble dietary fiber. Water-soluble dietary fiber mainly includes pectin, gum, etc., which is mainly found in beans, carrots, citrus. Insoluble dietary fiber includes cellulose, hemicellulose and lignin, which are found in the cell walls of plants. Common foods such as cereal, celery, and root vegetables contain high levels of insoluble fiber. Dietary fiber intake can increase the water content of the stool and increase the volume of stool, thus promoting bowel movement. Dietary fiber can likewise inhibit the rate of cholesterol absorption, while reducing the risk of gallstones, breast cancer, dental caries and other diseases. Dietary guidelines recommend a daily dietary fiber intake of about 25-30g, one-third of which is water-soluble dietary fiber.