The six classes of nutrients that the human body needs are proteins, fats, carbohydrates, vitamins, minerals and water. The body needs these nutrients to grow, maintain health, repair itself and function properly.
Three classes of nutrients, carbohydrates, proteins and fats, are classified as macronutrients because the body needs them in large amounts to maintain health. Vitamins and minerals are both considered micronutrients because they are needed in much smaller quantities. The average person consumes over 2 1/2 gallons of water and food each day, but only 1/8 teaspoon of that amount is vitamins and minerals.
Carbohydrates provide energy for the human body. They come in three different forms: fiber, simple carbohydrates and complex carbohydrates. Proteins build antibodies, enzymes, new tissues and other compounds. If there is a severe protein deficiency, the body uses its muscles to provide protein in a process called muscle wasting.
Fats have the highest content of calories and provide protection, insulation and energy. Extra fat is stored and used when the body runs out of carbohydrates. Vitamins regulate other cell functions and are necessary for metabolism, growth and development. Minerals help with muscle function, aid the nervous system and strengthen bones and teeth. Water carries nutrients to cells, removes waste and regulates body temperature.