You probably associate protein with building strong muscles, but in fact, this macronutrient is present in every cell in your body. Amino acids are the building blocks of protein. Protein is made of 20 different amino acids, but your body is capable of synthesizing half of these on its own. The other half you must consume through dietary sources. These 10 amino acids are referred to as "essential" amino acids.
The 10 Essentials
There are 10 amino acids identified as essential, although one of them, arginine, is really only essential for the young, according to Michael Davidson of the National High Magnetic Field Laboratory at Florida State University. The 10 essential amino acids are arginine, histadine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Functions of Essential Amino Acids
In addition to providing the structural backbone of protein, amino acids also function as a component of enzymes, chemicals your body uses to speed up the biological processes needed to sustain life. The amino acid content of a particular protein or enzyme determines its unique properties and functions. Histadine, for example, is important for the creation of histamine, an important part of your body's immune response. Threonine is necessary for creating porphyrin, which creates the pigment in red blood cells that binds iron. Valine is an amino acid that helps bind proteins together.
Foods Containing Amino Acids
Foods such as meat, fish and poultry are considered complete proteins, because they contain all the essential amino acids. Other animal-based foods, such as dairy products and eggs, are also considered complete proteins. Plant-based foods contain a variety of amino acids, but with the exception of soybeans and quinoa, do not contain all 10 amino acids at once. Such foods are considered incomplete proteins. Plant-based sources of amino acids include corn, beans, rice, legumes and nuts. Vegetarians can obtain adequate daily intake of amino acids by consuming a variety of these plant-based protein sources.
Amino Acid Deficiencies
It is important for vegans to consume a variety of foods rich in amino acids in order to avoid protein deficiency, but protein deficiencies are more commonly a result of poverty than of vegetarianism. Cornell University notes that protein-energy-malnutrition, or PEM, occurs in parts of the world where food supply limits the opportunity to obtain all of the essential amino acids. Severe PEM, also known as kwashiorkor can cause liver deterioration, anemia and skin inflammation.
- MedlinePlus: Protein in Diet
- The Biology Project; The Chemistry of Amino Acids; September 2003
- Institute of Medicine; Dietary Reference Intakes; Macronutrients; 2005
- Florida State University; The Amino Acid Collection; Michael W. Davidson; February 2004
- Cornell University: Effects of Protein Deficiency in Humans
- Go Ask Alice!; Complete and Incomplete Proteins in Grains and Vegetables?; August 2003