Health Benefits Of Aspartic Acid

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Aspartic acid is a nonessential amino acid produced in our bodies under normal physiological conditions through transamination of oxaloacetate or from ornithine and citrulline in the urea cycle to meet our daily requirements. ^[1] It can exist in two forms, namely, (1) L-aspartic acid, which can function as a precursor or building block for the synthesis of a number of molecules, including proteins, oligopeptides, purines, pyrimidines, and nucleic acids, ^[2] and (2) D-aspartic acid. In general, aspartic acid is involved in enzyme active centers and in the maintenance of protein solubility and ionic character and, due to being a charged amino acid, contributes to the buffering properties of proteins responsible for pH homeostasis in our bodies. ^[3]

As aforementioned, we can naturally synthesize aspartic acid, although a dietary intake of the amino acid through various food sources and supplements can help promote sufficient, healthy levels of aspartic acid in the body. Good aspartic acid-rich food items include egg whites, soybeans and soy meal, fish, seaweeds, tofu, pork, and beef, among others. ^[4]

Aspartic Acid and the Production of Testosterone and Other Reproductive Hormones

D-Aspartic acid has been claimed to be of beneficial effects to infertile men requiring a boost in testosterone levels and even to athletic individuals. A 1996 Italian study established the relationship between D-aspartic acid and hormonal activities, reporting that in in vitro experiments, this amino acid triggers testosterone synthesis and, in in vivo experiments, accumulates in the pituitary gland and testes of experimental rodents with a simultaneous increase in blood levels of luteinizing hormone, testosterone, and progesterone. ^[5] Another Italian study from Second University of Naples investigated the role of D-aspartic acid in male steroidogenesis and the amino acid’s effect on testosterone-dependent secondary sexual characteristics, but this time in experimental green frogs rather than rats. Short-term in vivo experiments demonstrated that the amino acid builds up in the testes and its injection leads to an increase in testosterone levels in both testes and plasma. Administration of other amino acids such as L-aspartic acid, D-glutamic acid, and L-glutamic acid rather than D-aspartic acid proved ineffective in elevating testosterone levels, suggesting that this increase comes as a result of D-aspartic acid uptake. ^[6]

Aside from testosterone, D-aspartic acid is also involved in the release and synthesis of luteinizing hormone, which induces ovulation and corpus luteum development in women. Topo et al. (2009) explained that D-aspartic acid triggers an augmentation of luteinizing hormone and testosterone release in humans. Furthermore, as observed in the pituitary glands of rats, such release and synthesis of luteinizing hormone involves cGMP as a second messenger. ^[7]

Aspartic Acid and Fatigue

Aspartic acid takes part in the synthesis of glucose and, via its metabolism in the Krebs cycle, contributes to energy production; in fact, it is said that low levels of aspartic acid may translate to lowered energy-generating capacity in cells. ^[8]

Aspartic Acid as Performance Enhancers

Although scientific evidence for claims of aspartic acid being an efficacious ergogenic aid is limited, it is assumed that L-aspartic acid improves performance during prolong and short-term intense physical activities by acting as a substrate for energy production in the Krebs cycle, conserving glycogen stores, and promoting a faster rate of glycogen resynthesis. ^[9]

Aspartic Acid and Opiate Dependence

L-Aspartic acid has been suggested to be of value in the treatment of signs of opiate abstinence syndrome, as it has been observed to reduce the compulsory intake of opiates by addicts and minimize physical dependence on the drug. In the study of Sener, Ceylan, and Koyuncuoğlu (1986), 8 g of L-aspartic acid was administered to 31 opiate addicts for 7 days after their withdrawal from opiate and the appearance of signs of abstinence syndrome. The effects of L-aspartic acid were then statistically compared with those of chlorpromazine plus diazepam, a drug combination used since then in therapy to suppress abstinence syndrome. The results revealed that the intensity and duration of a majority of abstinence syndrome signs (13 out of 16 signs) were more alleviated and shortened among addicts on L-aspartic acid treatment. ^[10]