The history of dietary fiber goes all the way back to ancient Greece. However, although it has been known since then that wheat bran^*1 is good for preventing constipation, dietary fiber was thought to be food waste that was not absorbed by the intestines, and was even thought to cause the excretion of essential nutrients. Moreover, since the texture of food suffers when it contains a lot of fiber, historically a lot of effort was put into creating white bread with less fiber. In the 1930s, J.H. Kellogg^*2 became interested in wheat bran and confirmed its effects on patients with constipation and colitis. British physician Eban Hipsley was the first person to use the term "dietary fiber."

There is currently no single consensus definition of dietary fiber among researchers. British physicians Drs. Burkitt and Trowell, who conducted medical activities in Africa from the 1940s onwards, published the opinion that the reason why native Africans had low rates of diseases such as diverticulosis, diabetes, gallstones, arteriosclerosis, and ischemic heart disease, which were frequently seen in developed countries, may be the result of a high intake of fiber.
At first, Dr. Trowell defined dietary fiber as "walls of the plant cells that are resistant to digestion by human enzymes."
However, as research advanced, it became clear that there were other substances with the same physiological action. At present, a universal definition is being debated. In Japan, the generally accepted concept is "the whole components of foods that resist digestion by human digestive enzymes (including those of animal origin as well as plant origin)."
According to this definition, dietary fiber includes the cellulose, lignin and pectin found in plants as well as the chitin, chitosan, starch and other components found in crustaceans such as crabs and shrimps. Some parts of the starch are non-digestible.