Aspartic acid, also commonly known as aspartate, is produced in the liver by bacteria from glutamate. Its main function is to generate and transport energy throughout the body. This article will discuss its metabolism, absorption, and toxic side effects.
Metabolism
Aspartic acid is synthesized in the liver from glutamate and relies on the cofactor pyridoxine (vitamin B6) for its conversion. Asparagine is mainly synthesized from aspartic acid and adenosine triphosphate (ATP), but it can also be produced from glutamate, requiring the mineral magnesium.
Forms and Absorption of Aspartic Acid
Aspartic acid exists in two forms: L-aspartic acid and D-aspartic acid. Food proteins contain L-aspartic acid (i.e., L-aspartic acid). Aspartic acid and glutamate compete for absorption in the brain, cortex, and spinal cord. This competitive absorption is one of the ways amino acid metabolism regulates the body.
The uptake of aspartic acid and glutamate is reduced in a damaged brain. Like other excitatory neurotransmitters, aspartic acid is decreased in the blood of patients with depression. Currently, aspartic acid is being investigated for its use in the treatment of depression.
Aspartic Acid Toxicity and Side Effects
Aspartic acid's toxicity is very similar to that of monosodium glutamate (SG). High doses of aspartic acid produce similar damage to the central nervous system in experimental animals, particularly the hypothalamus, leading to obesity, developmental delays, and reproductive dysfunction. Aspartic acid can reduce motor and exploratory behavior in experimental animals. It can also reduce fertility (abnormal levels of aspartic acid enzymes in abnormal sperm), decrease the volume of the pituitary gland, thyroid gland, ovaries, and testes, and cause retinal activity and damage, leading to retinal detachment. D-aspartic acid is more toxic than L-aspartic acid, causing growth inhibition in experimental animals. The doses of aspartic acid used in these studies are approximately 2 to 4 grams per kilogram of body weight, equivalent to 140 to 280 grams in a 70-kilogram adult male-a dose far exceeding any physiological or therapeutic use. Oral doses of up to 25 to 100 grams of aspartic acid may not produce toxic side effects in humans.
Precautions for Consuming Aspartame
Aspartic acid and phenylalanine are the raw materials for producing aspartame. Unfortunately, both can stimulate excitatory pathways in the brain. These excitatory pathways can exacerbate pain, irritability, mood swings, and even be associated with psychosis. They can also damage the entire body, including the lungs and brain, through precipitation, for example, in Alzheimer's disease.
Aspartame is a unique sugar substitute. Because it is a dipeptide compound and breaks down rapidly, it provides a strong sweet taste, hundreds of times sweeter than glucose, but with very low calories. In studies of aspartame, the dosage used was 34 mg/kg body weight, which is equivalent to 2 grams of aspartic acid in an average 70 kg adult. This dosage is insufficient to significantly increase blood levels of aspartic acid, asparagine, or glutamine; therefore, we can see that aspartame is safe to use. However, this does not apply to patients with phenylketonuria.