Although milk from the cow is processed, it is not an engineered or fabricated food. It is about 87 percent water and 13 percent solids. The fat portion of the milk contains fat soluble vitamins. The solids other than fat include proteins, carbohydrates, water soluble vitamins, and minerals. These nutrients in milk help make it nature's most nearly perfect food.
Milk products contain high quality proteins. The whey proteins constitute about 18 percent of the protein content of milk. Casein, a protein found only in milk, contains all of the essential amino acids. It accounts for 82 percent of the total proteins in milk and is used as a standard for evaluating protein of other foods. Protein is needed to build and repair body tissues and to form antibodies which circulate in the blood and help fight infection.
Milk also contains the following nutrients: calcium, phosphorus, magnesium, and potassium. The calcium found in milk is readily absorbed by the body. Phosphorus plays a role in calcium absorption and utilization. Phosphorus is needed in the proper ratio to calcium to form bone. Milk provides these two minerals in approximately the same ratio as found in bone. Milk is also a significant source of riboflavin (vitamin B2) which helps promote healthy skin and eyes, as well as vitamins A and D.
In adults, a calcium deficiency, along with other factors, may result in bone deterioration called osteoporosis. The recommendations for calcium are 1,000 milligrams for adults, 1,300 milligrams per day for adolescents, 500-800 milligrams per day for young children and 1,200 milligrams per day for adults over 51 years of age. One serving of milk has about 250 milligrams of calcium. It is difficult to obtain adequate calcium without milk and milk products in the diet. About 73 percent of the calcium available in the food supply is provided by milk and milk products. The following daily consumption of milk group foods is suggested by the government's U.S. Dietary Guidelines: