Glutamic Acid

What is it?

Glutamic acid (glutamate) is an amino acid used by the body to build proteins. Glutamate is the most common excitatory (stimulating) neurotransmitter in the central nervous system.

Under normal circumstances, humans are able to meet bodily glutamate requirements either from the diet or by making it from precursor molecules. Although glutamine and glutamic acid have similar names, they are structurally different.

The fluid produced by the prostate gland contains significant amounts of glutamic acid, and this amino acid may play a role in normal function of the prostate. In one study, symptoms of benign prostatic hyperplasia (BPH) were improved in a group of 45 men taking 780 mg of glutamic acid per day for two weeks and then 390 mg for the next two and a half months in combination with equal amounts of the amino acids, alanine and glycine,¹ an effect also reported by other researchers.²

Glutamic acid may have protective effects on the heart muscle in people with heart disease. Intravenous injections of glutamic acid (as monosodium glutamate) have been shown to increase exercise tolerance and heart function in people with stable angina pectoris.³

Where is it found?

Sources of glutamic acid include high-protein foods, such as meat, poultry, fish, eggs, and dairy products. Some protein-rich plant foods also supply glutamic acid.

Glutamic acid has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings	Health Concerns
	Benign prostatic hyperplasia
	Heart surgery (support)
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Who is likely to be deficient?

Most food sources of protein supply glutamic acid, so only a person deficient in protein would become deficient in glutamic acid.⁴

How much is usually taken?

Healthy people do not need to take glutamic acid as a supplement; for those who do use this amino acid, appropriate amounts should be determined with the consultation of a physician.

Are there any side effects or interactions?

Glutamic acid is generally free of side effects for the vast majority of people who take it; however, people with kidney or liver disease should not consume high intakes of amino acids without consulting a healthcare professional. Because over stimulation of glutamate receptors is thought to be a possible cause of certain neurological diseases (e.g., amyotrophic lateral sclerosis [Lou Gehrig’s disease] and epilepsy), people with a neurological disease should consult of physician before supplementing with glutamate.

Monosodium glutamate (MSG), the form of glutamic acid that is used as a flavour enhancer, has been reported in anecdotal studies to have a number of different adverse effects (including headache, fatigue, and depression). However, controlled trials have failed to confirm that MSG causes these side effects, and the safety of this compound remains controversial.

At the time of writing, there were no well-known drug interactions with glutamic acid.

References
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1. Damrau F. Benign prostatic hypertrophy: amino acid therapy for symptomatic relief. J Am Geriatr Soc 1962;10:426-30.

2. Feinblatt HM, Gant JC. Palliative treatment of benign prostatic hypertrophy. Value of glycine-alanine-glutamic acid combination. J Maine Med Assoc 1958;49:99-101, 124.

3. Thomassen A, Nielsen TT, Bagger JP, et al. Antiischemic and metabolic effects of glutamate during pacing in patients with stable angina pectoris secondary to either coronary artery disease or syndrome X. Am J Cardiol 1991;68:291-5.

4. Zello GA, Wykes LF, Ball RO, et al. Recent advances in methods of assessing dietary amino acid requirements for adult humans. J Nutr 1995;125:2907–15.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.

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