What Foods Are Considered to Be Perfect Protein Sources?

Many foods, including red meat, are perfect protein sources.

Proteins are made up of amino acids, which are considered the building blocks of life. Every chemical reaction your body preforms -- making new red blood cells, contracting muscles, converting sugar into energy -- requires proteins. In nature, there are perfect and imperfect proteins. Perfect proteins are those that contain all nine essential amino acids.

Essential and Nonessential Amino Acids

There are 20 amino acids that make up proteins, and they are divided into two categories, essential and nonessential. The nine essential amino acids are those that cannot be produced by the human body; thus they must be consumed through food or supplements. These are histidine, isoleucine, leucine, lysine, methionine, phenylalinine, threonine, tryptophan and valine. The body can make the remaining 11: alanine, arginine, aspartic acid, cysteine, cystine, glutamic acid, glutamine, glycine, proline, serine and tyrosine.

Animal Proteins

Many perfect proteins are derived from animal sources. Red meat, such as top ground round beef, is a perfect protein source, as are some types of poultry, including chicken and turkey breast. Other perfect protein sources include eggs, milk, cheese and yogurt. Although these have all the essential amino acids, they contain them in different amounts, so it is important to eat a wide variety of protein sources.

Vegetarian Sources

Because so many come from animal sources, finding perfect proteins that are compatible with a vegetarian diet can be challenging. Although many grains and nuts are high in protein, most of these protein sources lack one or more essential amino acids. The only plant that is commonly accepted as a complete protein source is soy. Soy and soybeans can be integrated into the diet in a variety of ways to maximize intake of perfect proteins.

Complete Protein Combinations

For those who are allergic or don't like soy, there are other ways to consume perfect proteins in a vegetarian diet. Plant proteins can be mixed in a variety of ways to create a perfect protein combination. A couple examples of food combinations that provide a perfect protein source are beans with rice and corn with beans. These dishes are compatible with a vegetarian diet while also supplying all nine essential amino acids.

References

• Northwestern University: Protein
• CDC: Nutrition for Everyone: Basics: Protein
• Medline Plus: Protein in Diet