General functions of these foodstuffs
| To supply energy |
| To supply building material |
| To regulate body processes |
Special functions of each foodstuff
| Proteins—supply energy; also nitrogen, sulphur, and sometimes phosphorus for body building |
| Fats—supply energy in the most concentrated form |
| Carbohydrates—supply energy in the most economical form |
| Mineral matter—supplies building material and helps to regulate body processes |
| Water—supplies necessary material (about 60 per cent of body being water) and helps to regulate body processes |
Examples of food materials rich in each of the foodstuffs
| Proteins |
| Eggs |
| Milk |
| Cheese |
| Lean meats |
| Fish |
| Fats |
| Cream |
| Butter |
| Meat fats |
| Vegetable oils |
| Nuts |
| Yolk of egg |
| Carbohydrates |
| Cereals and cereal products |
| Potatoes and other starchy |
| vegetables |
| Chestnuts |
| Sweet fruits |
| Sugar |
| Mineral matter |
| Milk |
| Green vegetables |
| Fruits |
| Whole wheat and other |
| whole cereal products |
| Egg yolk |
| Water |
| Fresh fruits |
| Fresh vegetables |
| Milk |
| Beverages, including water as such |
Digestion of the foodstuffs
Having seen what each of the foodstuffs does in nourishing the body, we may now see how they are prepared for the use of the body in the digestive tract.
Digestion of carbohydrate.—The simplest carbohydrate is a sugar which cannot be broken up into other sugars. Such a simple sugar is called a monosaccharid. There are two common in foods, glucose and fructose; a third, galactose, is derived from more complex sugars. Two simple sugars united chemically make a double sugar or disaccharid; thus cane sugar or sucrose will yield glucose and fructose, while milk sugar or lactose will yield glucose and galactose, and maltose will yield two portions of glucose. These three disaccharids are the only common ones. Starches, dextrins, and cellulose or vegetable fiber are made of many simple glucose