The protein one eats is digested into amino acids. Amino acids from meat, milk, eggs, beans, and fish link together to form thousands of different proteins that become part of the body. Proteins form the structure of the body; other proteins become antibodies to fight off infection, and still other proteins control and regulate cell activities.

Protein is necessary for good health throughout all stages of life.

More protein is needed when the body is growing rapidly especially during infancy and adolescence.  Growth and development can be inhibited by protein deficiency. Some of the missed growth cannot be made up later; therefore, it is important to maintain a healthy, balanced diet that includes appropriate sources of protein.

Complete vs Incomplete Protein

In nutrition, the quality of protein refers to types, amounts, and accessibility of amino acids in the food.

Proteins can be classified as either complete or incomplete.

Proteins that contain adequate amounts of all nine essential amino acids are termed complete proteins. Incomplete proteins do not contain adequate amounts of one or more of the essential amino acids. For example, if a protein doesn’t provide enough of the essential amino acid leucine, it would be considered incomplete.

Animal Sources of Protein

Meat, poultry, fish, eggs, and milk products are considered complete proteins. A balanced diet that includes all food groups in appropriate amounts will supply the necessary macronutrients needed daily.

Plant Sources of Protein

Plants are a source of protein but are not a complete protein unless combined with other sources of essential amino acids. Complimentary proteins are food sources that work together to provide all essential amino acids. By focusing on complimentary proteins, vegetarians can achieve an appropriate daily protein intake.

Complementary proteins do not need to be consumed at the same time or meal. It is currently recommended that essential amino acids needs be met on a daily basis, meaning that if a grain is consumed at one meal, a legume could be consumed at a later meal, and the proteins would still complement one another.

For more information on how vegetarians can achieve the appropriate amount of essential amino acids when foods are combined, visit the ChooseMyPlate Tips for Vegetarians website.