Food is vital for life. It can be defined as any solid or liquid substance which, when processed by the body, provides it with the necessary materials to enable it to grow, to replace worn-out and damaged parts, and to function normally.
The human body is like a complex piece of machinery in that its is prone to faults and weakness if it is poorly maintained. This can happen if too little or too much food is eaten or if the daily food intake is unbalanced.
One way of ensuring that health and fitness are maintained - when food is plentiful - is to have a good understanding of food and its impact on the body and to use that knowledge wisely.
Food, akin to other substances, is composed of different chemical elements, arranged in a variety of ways to form molecules. Collectively, these molecules give individual foods their flavour, colour, and texture and affect their reaction to heat and digestion.
The body uses some of the molecules in food to function correctly and to stay healthy - these are the nutrients. There are many different nutrients, each has its own function, and each nutrient is vital to the health of an individual.
The study of nutrients and their relationship with food and living things is, therefore, nutrition.
Most foods contain more than one nutrient so are of use to the body in numerous ways. However, some food stuffs, for example, sugar, contain only one nutrient and are therefore of limited use.
However, no single food provides all the nutrients required by the body in sufficient quantities, so a variety of foods must be eaten.
Common terms used in the study of nutrition include the following:
Diet: the food that a person normally eats every day. There are also special diets, e.g. slimming diets, low fat diets.
Malnutrition: an incorrect or unbalanced intake of nutrients.
Under-nutrition: an insufficient total intake of nutrients.
Balanced diet: a diet that provides the correct amount of nutrients for the needs of an individual.
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