Role of Protein in Good Nutrition

Protein is an essential nutrient whose name comes from the Greek word "protos," which means "first." To visualize a molecule of protein, think of a very long chain with links. These links represent amino acids, the building blocks of protein, which are essential for cell regulation, growth, and repair.

Key Functions

• The body uses protein to build new cells, maintain tissues and regulate cell function.
• About half of the protein consumed daily is converted into enzymes, the specialized "worker proteins" that regulate the speed of biological reactions in your body and permit it to perform functions such as digesting food and assembling or dividing molecules to make new cells and chemical substances. To perform these functions, enzymes often need specific vitamins and minerals.

To make all the proteins that the body needs, 22 different amino acids are required. Nine are considered to be essential, meaning they are not synthesized by the body and must be obtained from food. Our bodies can produce the other 13 from fats, carbohydrates, and other amino acids. So, these are referred to as non-essential amino acids.

Food Sources

Meat, poultry, fish, eggs, cheese, nuts, legumes, and soy

Usage

It is possible to consume too much protein. The amount of protein needed for good health varies.

• An average healthy adult man or woman needs about 0.8 grams of protein per every kilogram (2.2 pounds) of body weight.
• As you grow older, new proteins are synthesized less efficiently, and muscle mass (protein tissue) diminishes while fat content stays the same or rises. This is why muscle seems to "turn to fat" in old age.
• Infants, adolescents, pregnant women, individuals with injuries, and athletes may often require more protein on a daily basis.

Check with your local market for the recommended daily intake of protein.

Safety Evidence

Several medical conditions make it difficult for people to digest and process proteins properly. As a result, waste products build up in different parts of the body. Check with your physician for individual safety concerns you may have.