Description
L-aspartate is a protein amino acid naturally found in all life forms. L-aspartate is a dicarboxylic amino acid. Although most L-aspartate is in proteins, small amounts of free L-aspartate are found in body fluids and in plants. The normal diet contains about 2 grams of L-aspartate daily. L-aspartate is also in the alternative dipeptide sweetener aspartame; the amount of L-aspartate from the sweetener is a small fraction of total L-aspartate consumed.
L-aspartate is considered a non-essential amino acid, meaning that, under normal physiological conditions, sufficient amounts of the amino acid are synthesized in the body to meet the body's requirements. L-aspartate is formed by the transamination of the Krebs cycle intermediate oxaloacetate. The amino acid serves as a precursor for synthesis of proteins, oligopeptides, purines, pyrimidines, nucleic acids and L-arginine. L-aspartate is a glycogenic amino acid, and it can also promote energy production via its metabolism in the Krebs cycle. These latter activities were the rationale for the claim that supplemental aspartate has an anti-fatigue effect on skeletal muscle, a claim that was never confirmed.
L-aspartate is also known as L-amino succinate. Its IUPAC abbreviation is Asp. Its one-letter abbreviation, used when spelling out protein structures, is D. It is a solid, with an acid form that is slightly soluble in water, and with salt forms that are more water-soluble. Available salts include magnesium, calcium, potassium, zinc and combinations thereof. L-aspartate is used interchangeably with the term aspartic acid. The biological form of this substance, however, is the anion of aspartic acid, L-aspartate. Aspartic acid has the following chemical structure:
Chemical Structure
Aspartic acid
Actions & Pharmacology
Actions
L-aspartate salts are delivery forms for cations such as magnesium, potassium, calcium and zinc.
Mechanism of Action
L-aspartates can form salts with cations such as magnesium, potassium, calcium and zinc.
Pharmacokinetics
Following ingestion, L-aspartate is absorbed from the small intestine by an active transport process. Following absorption, L-aspartate enters the portal circulation and from there is transported to the liver, where much of it is metabolized to protein, purines, pyrmidines and L-arginine, and is catabolized as well. L-aspartate is not metabolized in the liver; it enters the systemic circulation, which distributes it to various tissues of the body. The cations associated with L-aspartate independently interact with various substances in the body and participate in various physiological processes.
Indications & Usage
There is no support for the claim that aspartates are exercise performance enhancers, i.e. ergogenic aids.
Overdosage
Overdosage has not been reported.
Dosage
L-aspartate salts of potassium, magnesium, calcium and zinc are available, as well as mixed salts of magnesium potassium aspartate and calcium magnesium aspartate. See Calcium, Magnesium, Potassium and Zinc for dose recommendations of these minerals.
Literature
Bac P, Pages N, Herrenknecht CLA, Teste JF. Inhibition of mouse-killing behavior in magnesium-deficient rats: effect of pharmacological doses of magnesium pidolate, magnesium aspartate, magnesium lactate, magnesium gluconate and magnesium chloride. Magnes Res. 1995; 8:37-45.de Haan A, van Doorn JE, Westra HG. Effects of potassium ++ magnesium aspartate on muscle metabolism and force development during short static exercise. Int J Sports Med. 1985; 6:44-49.Hagan RD, Upton SJ, Duncan JJ, et al. Absence of effect of potassium- magnesium aspartate on physiologic responses to prolonged work in aerobically trained men. Int J Sports Med. 1982; 3:177-181.Hicks JT. Treatment of fatigue in general practice: a double-blind study. Clinical Medicine. 1964; 71:85-90.Maughan RJ, Sadler DJ. The effects of oral administration of salts of aspartic acid on the metabolic response to prolonged exhausting exercise in man. Int J Sports Med. 1983; 4:119-123.Trudeau F, Murphy R. Effects of potassium-aspartate salt administration on glycogen use in the rat during a swimming stress. Physiol Behav. 1993; 54:7-12.Tuttle JL, Potteiger JA, Evans BW, Ozmun JC. Effects of acute potassium-magnesium aspartate supplementation on ammonia concentrations during and after resistance training. Int J Sport Nutr. 1995; 5:102-109.Research & Summary
There are claims that L-aspartate is a special type of mineral transporter for cations, such as magnesium, into cells. Magnesium aspartate has not been found to be more biologically effective when compared with other magnesium salts.
There are also claims that L-aspartate has ergogenic effects, that it enhances performance in both prolonged exercise and short intensive exercise. It is hypothesized that L-aspartate, especially the potassium magnesium aspartate salt, spares stores of muscle glycogen and/or promotes a faster rate of glycogen resynthesis during exercise. It has also been hypothesized that L-aspartate can enhance short intensive exercise by serving as a substrate for energy production in the Krebs cycle and for stimulating the purine nucleotide cycle.
An animal study using injected aspartate failed to find any evidence of a glycogen-sparing effect or any ergogenic effects whatsoever. A more recent double-blind human study of male weight trainers similarly found aspartate supplementation to have no effect, and another study of the effect of aspartate on short intensive exercise again found no effect.
Contraindications, Precautions & Adverse Reactions
Contraindications
L-aspartate supplementation is contraindicated in those hypersensitive to any component of the preparation.
Precautions
Because of lack of long-term safety studies, L-aspartate salts should be avoided by children, pregnant women and lactating women.
Adverse Reactions
Mild gastrointestinal side effects including diarrhea have been reported.
Interactions
No drug, nutritional supplement, food or herb interactions are known.
