Function: Serine is used to manufacture proteins, energy, cell membrane structure and synthesis of other cell components (DNA and RNA). Serine is a dispensable amino acid obtained from the diet and synthesized from other amino acids and metabolites of glucose. Serine participates in protein synthesis, energy production, phospholipid synthesis (phosphatidyl serine and ethanolamine) and one-carbon unit metabolism (necessary for DNA and RNA synthesis). Quantitatively, serine supplies more one-carbon units than any other nutrient. Serine is an attachment point for carbohydrates on protein chains. Deficiency Symptoms: No specific deficiency symptoms are known for serine; however, some individuals may have a metabolic defect in serine synthesis or conditional need for serine during periods of cell growth or physiological stress. Preliminary clinical evidence suggests neurological symptoms (neuropathy, neuritis, and behavioral disturbances may be associated with serine deficiencies. Additional laboratory tests to determine other aspects of serine metabolism would include amino acid analysis of serum and/or urine. Repletion Information: Since serine is a dispensable amino acid, no dietary RDA exists. Serine is present in foods that are rich in protein. Doses of 1-2 grams daily of pure serine appear safe.