The term food is used in two different ways and can be derived from the first meaning of the word which is to nourish the body with food or to sustain life. Food is generally of animal, plant or human origin, and comprises necessary nutrients, including proteins, carbohydrates, vitamins, or iron. Some foods are naturally rich in particular nutrients in varying proportions, whereas other foods are deficient in certain elements.
The first definition relates to the composition of food, that is, the proportion of essential amino acids to total protein in the dry form. In this sense food is considered complete when all the amino acids have been combined into a specific sequence that is missing from the rest of the body. This may be due to differences in the genetic code, or it may occur due to environmental influences. Animal products, for example, are very rich in protein, and the fact that these animals are fed on grass, grains, and other foods which do not contain complete proteins shows that they must obtain this protein from elsewhere. Similarly, plant foods, although they are often deprived of animal products, are also very rich in essential amino acids, which can only be gained by eating meat, eggs or other animal-based products.
In contrast, food which is described as incomplete contains no combination of the essential amino acids, and cannot grow or survive, but does not meet the requirements of the body. Such food can only be supplied from elsewhere, either by eating another food, or by using other resources, such as the energy extracted from food which is not suitable for the development of living things. Therefore, human beings use food to satisfy their basic needs, which in turn results in the growth of living things, and in turn brings them into existence. Through food, human beings have the ability to become a part of nature, independent of other people and their ways, and to live in harmony with all of the other living things on earth.