Search

Amino acids

Definition

Information

Amino acids are organic compounds that combine to form proteins . Amino acids and proteins are the building blocks of life.

When proteins are digested or broken down, amino acids are left. The human body uses amino acids to make proteins to help the body:

  • Break down food
  • Grow
  • Repair body tissue
  • Perform many other body functions

Amino acids can also be used as a source of energy by the body.

Amino acids are classified into three groups:

  • Essential amino acids
  • Nonessential amino acids
  • Conditional amino acids

  • Essential amino acids cannot be made by the body. As a result, they must come from food.
  • The nine essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan , and valine.

  • "Nonessential" means that our bodies produce an amino acid, even if we don't get it from the food we eat.
  • They include: alanine, asparagine, aspartic acid, and glutamic acid.

  • Conditional amino acids are usually not essential, except in times of illness and stress.
  • They include: arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine.

You do not need to eat essential and nonessential amino acids at every meal, but getting a balance of them over the whole day is important.

References

Trumbo P, Schlicker S, Yates AA, Poos M; Food and Nutrition Board of the Institute of Medicine, The National Academies. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. . 2002;102(11):1621-1630.

Escott-Stump S, eds. . 6th ed. Philadelphia Pa: Lippincott Williams & Wilkins; 2008.

Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.