There are six classes of fibre. They are cellulose, hemicellouse, pectin, gums, mucilages, and legnin. They differ in physical properties and chemical interactions in the gut, though all except legnin are poly-saceharides. The facts known so far about these forms of fibre as a result of various studies are discussed below.

Cellulose: It is the most prevalent fibre. It is fibrous and softens the stool. It abounds in fruits, vegetables, bran, whole-meal bread and beans. It is also present in nuts and seeds. It increases the bulk of intestinal waste and eases it quickly through the colon. Investigations indicate that these actions may dilute and flush cancer-causing toxins out of the intestinal tract. They also suggest that cellulose may help level out glucose in the blood and curb weight gain.

Hermicellulose: It is usually present wherever cellulose is and shares some of its traits. Like cellulose, it helps relieve con- stipation, waters down carcinogens in the bowel and aids in weight reduction. Both cellulose and hemicellulose undergo some bacterial breakdown in the large intestine and this produces gas.

Pectin: This form of fibre is highly beneficial in reducing serum cholesterol levels. It, however, does not have influence on the stool and does nothing to prevent constipation. Researchs are being conducted to ascertain if pectin can help eliminate bile acids through the intestinal tract thereby preventing gallstones and colon cancer. It is found in apples, grapes, berries, citrus fruits, guava, raw papaya, and bran.

Gums and Mucilages: They are the sticky fibres found in dried beans, oat bran and oatmeal. Investigations have shown that they are useful in the dietary control of diabetes and cholesterol.

Legnin: The main function of legnin is to escort bile acid and cholesterol out of the intestines. There is some evidence that it may prevent the formation of gallstones. It is contained in cereals, bran, whole meal flour, raspberries, strawberries, cab- bage, spinach, parsley and tomatoes. The best way to increase fibre content in the diet is to increase the constipation of wholemeal bread, brown rice, peas beans, lentils, root vegetables and sugar -containing fruits, such as dates, apples, pears and bananas. The intake of sugar, refined cereals, meat, eggs and dairy products should be reduced. Candies, pastries, cakes which are rich in both sugar and fat, should be taken sparingly. White processed bread should be completely eliminated from the diet.

Requirement:

There are divergent views as to the requirement of dietary fibre for good health. There is no recommended daily dietary allowance for it and hardly any data about optimum amounts. Some Africans known for lower incidence of degenerative diseases take about 150 grams of fibre a day. In Europe and North America, where there is a high incidence of such diseases, people take 25 grams or less a day. Dr. John H. Cummings, a noted fibre expert in England, considers that a fibre intake of 30 grams (about one ounce) per day is sufficient for good health.

Excessive consumption of fibre, especially bran, should however, be avoided. Due to its content of crude fibre, bran is relatively harsh and it may irritate the delicate functioning of the digestive system, especially in the sick and the weak. Excessive use of fibre may also result in loss of valuable minerals like calcium, phosphorus, magnesium, and potassium from the body through excretion due to quick passage of food from the intestine.