The seven essential nutrients are water, fiber, vitamins, minerals, protein, carbohydrates and fats. The human body cannot make essential nutrients on its own, so it is necessary to get them from foods and beverages.
Protein, fats and carbohydrates are classified as macronutrients, or nutrients that provide the body with energy. Protein and carbohydrates each contain 4 calories per gram, while fats contain 9 calories per gram. Protein is necessary for growth, enzyme and hormone production, tissue repair, and the preservation of lean muscle mass.
The human body uses fats to protect the organs, maintain cell membranes and absorb some vitamins. Fats are also the most concentrated source of energy in the body. Carbohydrates act as the body's primary source of fuel. They also help the muscles, brain, digestive system and kidneys work properly.
Vitamins are either water soluble or fat soluble. The fat-soluble vitamins are absorbed by fatty tissue and then stored in the liver. Vitamins A, E, D and K are all classified as fat-soluble vitamins. Water-soluble vitamins dissolve in water, so they are not stored in the body's tissues. B-complex vitamins and vitamin C are water-soluble vitamins.
The human body needs minerals to grow and develop. These minerals have a variety of functions, from transmitting nerve impulses to helping the heart beat normally. Calcium, sodium, potassium and magnesium are examples of minerals humans need.
Fiber helps people feel full after meals and aids in digestion. Eating fiber-rich foods also helps with weight control. Whole grains, fruits and vegetables are good sources of fiber.