Monograph

L-Tyrosine, an amino acid associated with well-being, may help you manage stressful conditions with improved energy and endurance, enhanced mood, and mental clarity. As a precursor to the “mood and energy enhancing” neurotransmitters dopamine, norepinephrine, and adrenaline, L-Tyrosine supports the stress response system.
 

Description

L-Tyrosine is a protein amino acid that is naturally produced in the body. Supplementation may be necessary to meet the body’s demands, as certain physiological conditions suppress L-Tyrosine production.

Research

Stress & Cognitive Function

Several studies have found L-Tyrosine significantly improves cognitive function during environmental or behavioral stress. Healthy individuals were recruited to perform stress sensitive tasks after taking L-Tyrosine (100 mg) or a placebo. L-Tyrosine improved cognitive function one hour after administration and lowered blood pressure 15 minutes after ingestion.[1]

A similar study reviewed the effects of L-Tyrosine (2 g) on cognitive performance in military cadets during combat training. In comparison to the placebo group, subjects taking L-Tyrosine performed significantly better on cognitive tasks and blood pressure decreased. Researchers concluded L-Tyrosine minimized stress and fatigue to improve cognitive function.[2]

Cognitive performance can be dramatically deferred when an individual is exposed to environmental stress. One study found L-Tyrosine improved cognitive performance after the body core temperature was lowered in individuals exposed to cold water.[3]

Individuals exposed to a modulation that produced cardiovascular stress found that L-Tyrosine (100 mg/kg of body weight) augmented cognitive alertness during the stressful incident.[4]

Memory is often compromised during stress. One study observed L-Tyrosine (150 mg) improved short-term memory in subjects an hour after administration.[5] A similar study found memory decrements associated with environmental stress could be alleviated with 300 mg of L-Tyrosine.[6]

Individuals experiencing long durations of sleeplessness can have poor cognitive function and performance. One study examined the behavioral effects of L-Tyrosine on sleep loss with subjects involved in continuous nighttime work. Results indicated L-Tyrosine improved cognitive performance among individuals with sleep loss.[7]

Additional Information – Dosage & Interactions

Suggested Use

As a dietary supplement, take one capsule daily, or as directed by a physician.

L-Tyrosine works best when taken 30 minutes before a meal. It should not be taken with other amino acids or with proteins.

Dosage

Up to 1500 mg per day

Precautions

The maximum safe dosage of this supplement has not been determined for children, pregnant or nursing women, or those with severe liver or kidney disease. As with all supplement regimens, please consult your physician prior to use.

Individuals with high blood pressure should exercise caution while taking L-Tyrosine, as it can raise blood pressure levels in some individuals. Individuals with melanoma should avoid L-Tyrosine, as it can increase cellular growth rate. L-Tyrosine is typically well-tolerated, though minor reports have experienced gastrointestinal upset, insomnia, nervousness, or headaches.

Drug Interactions

Consult your physician before supplementing with L-Tyrosine if you are taking the following medications.

MAOIs – Deprenyl, Eldepryl, Marplan, etc.

Bendopa, Sinemet

Ritalin

*Statements made herein have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

References

[1] Deijen, JB, Orlebeke, JF. Effect of Tyrosine on cognitive function and blood pressure under stress. Brain Res Bull. 1994; 33(3):319-323.

[2] Deijen, JB, Wientjes, CJ, et al. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull. 1999 Jan; 48(2):203-209.

[3] O'Brien, C, Mahoney, C, et al. Dietary Tyrosine benefits cognitive and psychomotor performance during body cooling. Phsyiol Behav. 2007 Feb; 90(2-3):301-307.

[4] Dollins, AB, Krock, LP, et al. L-Tyrosine ameliorates some effects of lower body negative pressure stress. Physiol Behav. 1995 Feb; 57(2):223-230.

[5] Thomas, JR, Lockwood, PA, et al. Tyrosine improves working memory in a multitasking environment. Pharmacol Biochem Behav. 1999 Nov; 64(3):495-500.

[6] Mahoney, CR, Castellani, J, et al. Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiol Behav. 2007 Nov; 92(4):575-582.

[7] Neri, DF, Wiegmann, D, Stanny, RR, et al. The effects of Tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med. 1995 Apr; 66(4):313-319.