Foods are made up of five basic types of nutrients: carbohydrates, fats, proteins, vitamins, and minerals. Carbohydrates are a source of energy and consist mostly of starches and sugars of vegetable origin, such as cereals and tubers. Fats and oils provide the most concentrated source of energy, having more than twice the energy content per weight of carbohydrates and proteins. In most poor countries, most energy is derived from staple foods, especially cereals, with fats accounting for a much smaller portion. Proteins are bodybuilding substances required for growth and tissue repair. Protein is found in foods of animal origin, cereals, and legumes. Vitamins and minerals are needed in small quantities for the adequate functioning of the body. Individual vitamins and minerals or combinations are found in all foods in variable amounts.
If the energy intake is inadequate, some protein in the body will burn to provide energy instead of promoting body growth or repair. That is, it will be used in the same way as carbohydrates or fats. No less than 10 percent of the energy requirement should be supplied from fats and oils. They also greatly enhance the palatability of the diet and increase energy density, which is important for younger children. Energy requirements vary widely, even among normal individuals, and increase with physical activity. Much higher intakes are required for the treatment of malnutrition, when the aim is rehabilitation rather than maintenance.
Diets in most countries contain adequate amounts of nutrients required for good health if enough of the diet is taken to satisfy the individual’s energy requirements. Even a growing, healthy child requires no more than 10 percent of the calories to be supplied from protein sources.