As a group, amino acids play an important role in protein synthesis and metabolism. Aspartic acid and glutamic acid are examples of nonessential amino acids, or those your body can manufacture. In total, there are 20 amino acids. Although each one is identical in their basic structure, every amino acid includes a side chain that makes it different from the rest and determines the role it plays in protein synthesis and metabolism.
In addition to sharing membership in the category of nonessential amino acids, aspartic acid and glutamic acid share two other characteristics. Both are acidic and both are polar, says the Virtual Chembook, a chemistry information site created by Elmhurst College at Elmhurst Illinois. Although eight additional amino acids also share the characteristic of polarity, the two acid groups and one amine group that form the structure of the side chain in aspartic and glutamic acid make them the only two acidic amino acids. Since polarity determines water solubility and an acidic side chain affects the degree of water solubility, these characteristics make aspartic and glutamic acid among the most hydrophilic. Their high affinity for water and the tendency for likes to attract is the reason aspartic acid and glutamic acid orient themselves on the outside of a protein molecule, closer to a watery environment.
Aspartic and glutamic acid function within your central nervous system as excitatory neurotransmitters that work to stimulate your brain, according to HumanNeurophysiology.com. Independently, aspartic acid’s main function is to assist in the synthesis of other amino acids. Glutamic acid functions in sugar and fat metabolism, supplies glucose to your brain, plays a role in thought and memory and facilitates potassium transfer through the blood-brain barrier.
In most cases, the amount of aspartic acid and glutamic acid produced by your body makes getting it from your diet or via supplements unnecessary. If your body fails to produce sufficient amounts of either, you can prevent symptoms such as insomnia, fatigue and depression by getting it from your diet. Foods sources for aspartic acid include dairy products, beef, fish, poultry and seeds. You can find glutamic acid in foods such as shellfish, turkey and cottage cheese.
Low levels of aspartic and glutamic acid may contribute to a medical condition called narcolepsy, a disease characterized by excessive daytime sleepiness. According to Dr. John Neustadt, author and medical director of Montana Integrative Medicine, low levels of aspartic and glutamic acid, both closely associated with many energy-producing processes within your body, affect the synthesis of chemical compounds not present in narcolepsy patients.
Claims that acidic amino acid food additives such as monosodium glutamate and aspartame threaten normal brain function are false, according to a report by Dr. John D. Fenstrom published in the "Journal of the American Dietetic Association." Dr. Fenstrom states that because dietary aspartic acid has no pathway to reach the brain and glutamic acid has severely limited access, neither affects the level of acidic amino acids in your brain and neither poses a threat to normal brain function.