Valine

Description

Valine is an essential amino acid. This means that it must be obtained through the diet in adequate quantities to meet the body's needs.

Valine is a member of the branched-chain amino acid family, along with leucine and isoleucine. The three branched-chain amino acids constitute approximately 70% of the amino acids in the body proteins. As such, their value in the formation and maintenance of structural and functional integrity in humans is unmeasured.

Valine also participates in the detoxification of ammonia and works along with alpha-ketoglutarate. It may be an important amino acid in the prevention of muscle wasting in diabetes and in the prevention of ammonia toxicity in older-aged individuals who are hospitalized.

Recent studies have indicated valine, leucine, and isoleucine supplementation can aid in muscle repair in individuals who have been seriously injured. It has been found after injury an individual mobilizes the branched-chain amino acids from his or her muscles to synthesize glucose in the liver. Supplementation with valine and the other two branched-chain amino acids may be very helpful in preventing muscle breakdown after trauma. Levels of supplementation vary between 200 and 1,000mg along with balanced levels of leucine and isoleucine.

Recommended Dietary Allowances

The RDA for valine has been established as 65mg per day for women and 80mg per day for men.

Food Sources

Foods high in valine include:

Cottage cheese - dry	2,500 mg/cup
Cottage cheese - creamed	1,769 mg/cup
Fish and other seafoods	1,000-7,000 mg/lb.
Meats	1,500-5,500 mg/lb.
Poultry	2,500-5,500 mg/lb.
Peanut, roasted with skin	3,500 mg/cup
Sesame seed	2,000 mg/cup
Dry, whole lentils	2,500 mg/cup

Method of Action

An inborn error in valine metabolism is seen in small percentage of people and can lead to "maple syrup urine disease". Faulty degradation of the amino acid results from blockage of oxidative decarboxylation and occurs along with inappropriate metabolism of leucine and isoleucine in this unusual genetic metabolism disorder. In these individuals, supplementation with branched-chain amino acids would be contraindicative.

Degradation of the branched-chain amino acids creates a series of branched fatty acid starter pieces, whose utilization leads to the formation of fatty acids that can be incorporated into complex phospholipids. The branched-chain amino acids have a unique muscle-sparing ability due to their gluconeogenic activity.

References

Adibi, S. Roles of Branched-Chain Amino Acids in Metabolic Regulation, J. Lab. Clin. Med., 95:475-84, 1980.

Blackburn, G., J. Grant, V. Young, ed., Amino Acids Metabolism and Medical Applications.

Glass, A., R. Bongiovanni, C. Smith, & T. Boehm, Normal Valine Disposal in Obese Subjects with Impaired Glucose Disposal: Evidence for Selective Insulin Resistance, Metab, 30:578-82, 1981.

Munro, H. & M. Crim. The Proteins and Amino Acids. Modern Nutrition in Health & Disease, eds: R. Goodhart & M. Shils. Phila. Lea & Febiger, 1980

Young, V., M. Meguid, D. Meredith & D. Bier. Recent Developments in Knowledge of Human Amino Acid Requirements. Nitrogen Metabolism in Man, eds: J. Waterlow and J. Stephen. London: Applied Science Publ 1981.