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Consult your doctorSome people with depression have been found to improve with tyrosine. (more)
Tyrosine is an amino acid used by the body to produce certain adrenal stress hormones and chemical messengers in the nervous system (neurotransmitters). Animal research shows that brain levels of these substances decline with stress, and that giving animals tyrosine supplements reverses this decline and improves various tests of performance in stressed animals.1 In a controlled study, a protein drink containing 10 grams per day of tyrosine was more effective than a carbohydrate drink for improving mental performance scores in a group of cadets taking a stressful six-day combat training course.2 A double-blind trial in humans found that one-time administration of 150 mg of tyrosine per 2.2 pounds of body weight helped prevent a decline in mental performance for about three hours during a night of sleep deprivation.3 Single administrations of tyrosine (100 to 150 mg per 2.2 pounds of body weight) have also helped preserve mental performance during physically stressful conditions such as noise or extreme cold in several controlled studies.4, 5, 6, 7
1. Owasoyo JO, Neri DF, Lamberth JG. Tyrosine and its potential use as a countermeasure to performance decrement in military sustained operations. Aviat Space Environ Med 1992;63:364-9 [review].
2. Deijen JB, Wientjes CJ, Vullinghs HF, et al. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull1999;48:203-9.
3. Neri DF, Wiegmann D, Stanny RR, et al. The effects of tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med 1995;66:313-9.
4. Banderet LE, Lieberman HR. Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Brain Res Bull 1989;22:759-62.
5. Shurtleff D, Thomas JR, Schrot J, et al. Tyrosine reverses a cold-induced working memory deficit in humans. Pharmacol Biochem Behav 1994;47:935-41.
6. Deijen JB, Orlebeke JF. Effect of tyrosine on cognitive function and blood pressure under stress. Brain Res Bull 1994;33:319-23.
7. Dollins AB, Krock LP, Storm WF, et al. L-tyrosine ameliorates some effects of lower body negative pressure stress. Physiol Behav 1995;57:223-30.
Consult your doctor
The amino acid L-tyrosine can be converted into norepinephrine, a neurotransmitter that affects mood. Women taking oral contraceptives have lower levels of tyrosine, and some researchers think this might be related to depression caused by birth control pills.1 L-tyrosine metabolism may also be abnormal in other depressed people2 and preliminary research suggests supplementation might help.3, 4 Several doctors recommend a 12-week trial of L-tyrosine supplementation for people who are depressed. Published research has used a very high amount—100 mg per 2.2 pounds of body weight (or about 7 grams per day for an average adult). It is not known whether such high amounts are necessary to produce an antidepressant effect.
1. Rose DP, Cramp DG. Reduction of plasma tyrosine by oral contraceptives and oestrogens: a possible consequence of tyrosine aminotransferase induction. Clin Chim Acta 1970;29:49-53.
2. Moller SE. Tryptophan and tyrosine availability and oral contraceptives. Lancet 1979;2:472 [letter].
3. Kishimoto H, Hama Y. The level and diurnal rhythm of plasma tryptophan and tyrosine in manic-depressive patients. Yokohama Med Bull 1976;27:89-97.
4. Gelenberg AJ, Wojcik JD, Growdon JH, et al. Tyrosine for the treatment of depression. Am J Psychiatry 1980;137:622-3.
L-tyrosine is a nonessential amino acid (protein building block) that the body synthesizes from phenylalanine, another amino acid. Tyrosine is important to the structure of almost all proteins in the body. It is also the precursor of several neurotransmitters, including L-dopa, dopamine, norepinephrine, and epinephrine.
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The information presented by 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. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2018.
WARNINGS: Persons with thyroid disease (hyperthyroidism), melanoma, or those taking MAO inhibitors or other mood altering medications should seek the advice of a physician before consuming this product.