Amino acids are organic compounds that come together to form proteins, and together they are the building blocks of life. In your body, when proteins are digested, amino acids remain and help to digest food, grow and repair body tissue and perform a variety of other functions. In structure, amino acids are broken down into four different categories, known as non-polar and neutral, polar and neutral, acidic and polar, and basic and polar. When it comes to your body, amino acids are broken down into three main categories known as essential, nonessential and conditional.
Characteristics of Amino Acid Structure
Amino acids are made from at least one amine and one acid, thus the name amino acid. The different variations in structure on the side chains of the amino acids are what create the different groups. The non-polar and neutral group includes valine, alanine, leucine, isoleucine and phenylalanine. The polar and neutral group includes aspartic acid, serine and tyrosine. The acidic group includes aspartic and glutamic and the basic group includes lysine, arginine and histidine.
Essential Amino Acids
Essential amino acids are necessary for the body but the body is unable to make them on its own so they must be acquired through the foods you eat. Essential amino acids include histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan and valine. Essential amino acids can be acquired through regular dietary intake of proteins in meats, fish, grains and vegetables. Your body digests the proteins and the amino acids you need are delivered to your body.
Nonessential Amino Acids
Nonessential amino acids are needed by the body in order to function properly but your body is able to make these amino acids on its own. Nonessential amino acids include alanine, asparagine, aspartic acid and glutamic acid. While your body is able to make these nonessential amino acids, they are also introduced into your body through the protein you eat. When the proteins are broken, the amino acids you need are released.
Conditional Amino Acids
Conditional amino acids are in a category a bit different than the others. These amino acids are not essential for health on most occasions, but become necessary in times of illness or stress. Conditional amino acids include arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline and serine. A 2003 study published in the "Current Opinion in Clinical Nutrition and Metabolic Care" looked at the use of L-glutamine supplementation in patients with critical illnesses. They concluded that high-dose glutamine therapy enhanced the body's ability to mount a stress response, improved immune cell function and decreased mortality.
References
- Virtual Chembook at Elmhurst College: Characteristics and Properties of Amino Acids
- MedlinePlus; Amino Acids; February 8, 2011
- "Current Opinion in Clinical Nutrition and Metabolic Care"; Role of L-Glutamine in Critical Illness; D. Kelly, et al.; March 2003
- Clackamas Community College; Protein in the Diet; Sue Eggling
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