These five items along with water are considered the nutrients which are necessary for the growth, maintenance, and repair of the human body. From these six categories of nutrients, our bodies get all the building blocks to grow and maintain life and health.

These nutrients can be divided into two categories: energy-yielding (carbohydrate, fat, protein) and non-energy-yielding (water, vitamins, and minerals). The energy-yielding nutrients are our primary food source. They provide the energy that every cell and every organ needs to function. The amount of energy released by these nutrients is measured in calories, a term with which we are all familiar. The body burns calories (i.e., uses energy) to power physical activity. People often think of calories as an element of the food, but actually it is a measure of energy provided by food. The energy content of food depends on how much carbohydrate, fat, and protein it contains.

Vitamins and minerals don't provide energy, but are important because they are involved in most all of the chemical reactions that occur in the body. Enzymes, hormones, antibodies all require vitamins and minerals in order to function. Healing, repair, and maintenance all require the presence of adequate vitamins and minerals. Without adequate vitamins and minerals the body slowly degenerates. This is seen as premature aging and the development of degenerative disease.

Some vitamins can be synthesized by the body from other nutrients. Some nutrients are classified as "essential" because the body cannot make them in sufficient quantities to meet its needs and so must obtain them directly from the diet. All minerals, many vitamins, some protein and some fats are considered essential nutrients. If you lack any one of these essential nutrients your health will be severely affected.

In the processing and refining of foods, vitamins and minerals are often removed or destroyed, leaving behind a food rich in calories but low in vitamins and minerals. For example, when whole wheat is milled and transformed into white flour, the vitamin-and mineral-rich bran and germ of the wheat kernel are removed and discarded. The resulting white flour is rich in starch (carbohydrate) and calories, but seriously depleted in vitamins and minerals. So the calorie content remains high while the nutritional content decreases. Likewise, when fresh oranges are transformed into orange juice the heat involved in processing destroys much of the vitamins. Calorie content remains the same but nutritional value decreases. Often sugar is added to give the juice a sweeter taste, thus increasing calorie content. This is pretty much the same with any processed food. Generally, the more processing a food undergoes, the lower its vitamin and mineral content while calorie content remains the same or increases. Highly processed or refined foods can supply the energy you need to carry on daily activities, but they do not supply all the vitamins and minerals you need to be healthy.

A high calorie, low vitamin and mineral diet gives a person a false sense of security. We can eat plenty of food, feel full, and may even be overweight, yet still be undernourished. For these reasons we need to choose the types of foods we eat carefully, selecting fresh, whole foods over highly processed, refined ones.