Threonine

Description

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

Threonine is useful in the stabilization of blood sugar because it can be converted into glucose in the liver by the process of gluconeogenesis. Individuals who have undergone burns or trauma have been found to have greater urinary spill of threonine, indicating it is mobilized from tissues after a trauma. Recent research indicates increasing threonine intake during these periods may help in the recovery after injury.

Therapeutic doses of threonine range from 300 to 1,200mg per day. Threonine is known to require vitamin B-6, magnesium, and niacin for its optimal utilization and metabolism in the body. It is therapeutically useful when administered along with the branched-chain amino acids valine, isoleucine, and leucine.

Recommended Dietary Allowances

The RDA for threonine has been established as 31mg per day for women and 50mg per day for men.

Food Sources

Foods high in threonine include:

Cottage cheese - dry	2,000 mg/cup
Cottage cheese - creamed	1,434 mg/cup
Fish and other seafoods	800-6,500 mg/lb.
Meats	1,000-4,500 mg/lb.
Poultry	2,000-4,000 mg/lb.
Peanut, roasted with skin	2,000 mg/cup
Sesame seed	1,500 mg/cup
Dry, whole lentils	1,750 mg/cup

Method of Action

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

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

Munro, H. & Crim, M. The Proteins and Amino Acids. Modern Nutrition in Health & Disease, eds. R. Goodhart & M. Shils. 6 ed. Phila. Lea and Febiger, 1980.

Pardridge, W. & Oldendorf, W. Kinetic Analysis of Blood-Brain Barrier Transport of Amino Acids. Biochim. Biophys. Acta, 401:128-36, 1975.

Tews, J., Bradford, A., & Harper, A. Induction of Lysine Imbalance in Rats: Relationships Between Tissue Amino Acids and Diet. J. Nutr., 111:968-78, 1981.

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