Serine

Description

Serine is a nonessential amino acid, which means it is manufactured from other amino acids in the liver; it does not have to be obtained directly through the diet.

Serine stimulates the synthesis of glucose (blood sugar) in the liver. For this reason, eating protein foods that are rich in serine will help stabilize the body against oscillations of blood sugar levels after eating. Serine is known to be the precursor to cysteine, along with methionine. It is also the precursor to glycine. Serine works in conjunction with alanine and glycine to help stabilize blood sugar and provide a timed-release source of glucose after glycogen depletion.

Deficiencies of a nonessential amino acid will not occur if a well-balanced diet is consumed because the intake of proper foods will allow the body to produce exactly the amount of amino acid required to function optimally.

Recently serine has been administered along with alanine and glycine to help management blood sugar problems associated with reactive hypoglycemia. Therapeutic doses of serine range between 300 and 1,000mg per day.

Recommended Dietary Allowances

Serine is a nonessential amino acid therefore an RDA has not been established. Serine is readily metabolized and has a wide safety margin.

Food Sources

Serine is a nonessential amino acid, which means it is manufactured from other amino acids in the liver; it does not have to be obtained directly through the diet.

Method of Action

Serine relates to the interconversion to glucose by the way of gluconeogenesis. It also relates to many other substances including sphingosine and the phosphatides, which are part of the myelin covering of the nerves. Conversion of one serine intermediate provides the formation of cysteine from methionine.

Serine is also a major source of glycine and the formation of single-carbon units needed for the synthesis of methyl groups, which are used in steroid biosynthesis. Because the body's capacity to generate methyl groups is limited, the vitamin B-complex vitamin choline, under certain circumstances, is a dietary essential nutrient and has been classified as a vitamin. However, in the presence of adequate amounts of folic acid and vitamin B-12 along with serine, it is not absolutely essential. Serine works with choline to help reform phosphatidylcholine, which is a major component of lecithin. A large number of substances are able to donate methyl groups, including betaine and methionine, which all interrelate with the amino acid serine.

References

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

Munro, H.N. & Crim, M.C. The Proteins and Amino Acids. Modern Nutrition in Health and Disease, eds. R.S. Goodhart & M.E. Shils, Sixth Edition. Philadelphia: Lea and Febiger, 1980.

Pitts, R.F. & MacLeod, M.B. Synthesis of Serine by the Dog Kidney In Vivo. Am. J. Physiol., 222:394, 1972.

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

Tews, J.K., Kim, Y-W.L. & Harper, A.E. Induction of Threonine Imbalance by Dispensable Amino Acids: Relationships Between Tissue Amino Acids and Diet in Rats. J. Nutr., 110:394-408, 1980.

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