Tyrosine is a nonessential amino acid. It is synthesized in the body from
phenylalanine and is a precursor of adrenaline (epinephrine), norepinephrine,
dopamine, thyroid hormones, and some types of estrogen. In order for tyrosine to
metabolize into these substances, folic acid, niacin, vitamin C, and copper are
needed. Low levels of tyrosine can lead to deficiencies in norepinephrine and
dopamine—neurotransmitters that regulate mood.
Depression can result. Animal studies have demonstrated that stressed animals
have reduced levels of norepinephrine; however, administration of tyrosine
prevented a norepinephrine deficiency. Tyrosine deficiency is also associated
with low blood pressure, low body temperature, and restless leg syndrome.
Tyrosine aids in the the production of melanin (pigment responsible for hair
and skin color) and in the functions of the adrenal, thyroid, and pituitary
glands. A deficiency of tyrosine has been associated with hypothyroidism.
Because tyrosine binds unstable molecules that can potentially cause damage
to the cells and tissues, it is considered a mild antioxidant. Thus, it may be
useful in heavy smokers and in individuals exposed to chemicals and
Although tyrosine is found in soy products, chicken, fish, almonds, avocados,
bananas, dairy products, lima beans, pumpkin seeds, and sesame seeds, it is
difficult to get therapeutic amounts of it from food. It is also produced from
phenylalanine in the body.
Many tyrosine supplements are available.
- Depression. Tyrosine appears to be a safe and effective treatment for
depression; however, symptoms of depression recur when tyrosine is discontinued.
Most data regarding tyrosine's efficacy in treating depression are
- Stress. Tyrosine seems to relieve the physical symptoms of stress if
administered before the stressful situation, though limited human studies have
- Premenstrual syndrome (PMS). Though most data are anecdotal, tyrosine
appears to help reduce the irritability, depression, and fatigue associated with
- Low sex drive. Tyrosine appears to stimulate the libido.
- Parkinson's disease. Parkinson's disease is treated with L-dopa,
which is made from tyrosine; thus, the effects of tyrosine supplementation is
being studied in Parkinson's disease patients.
- Weight loss. Tyrosine is an appetite suppressant and helps to reduce
- Chronic fatigue and narcolepsy. Tyrosine appears to have a mild
stimulatory effect on the central nervous system.
- Drug detoxification. Tyrosine appears to be a successful adjunct for
the treatment of cocaine abuse and withdrawal. It is often used in conjunction
with tryptophan and imipramine (an antidepressant). In one study, 75% to 80% of
patients treated with tyrosine stopped cocaine use completely or decreased usage
by 50%. Successful withdrawal from caffeine and nicotine has also been
- Phenylketonuria (PKU). Tyrosine supplementation is advocated in
patients with PKU; however, it is necessary to control plasma tyrosine levels
(normal: 45 mcmol/L) before tyrosine supplementation is considered.
|Dosage Ranges and Duration of
- For depression, premenstrual syndrome, and chronic fatigue, a 500 to
1,000 mg dose before each of three meals is recommended.
- For stress, 1,500 mg/day is recommended.
- For low sex drive, Parkinson's disease, drug detoxification, and
weight loss, 1 to 2 g/day in divided doses is recommended.
- It appears that up to 12 g/day of tyrosine can be ingested safely.
However, high-dose therapy should be monitored by a health care provider.
- Migraine headache
- High blood pressure
- Mild gastric upset
- Promotes cancer cell
Tyrosine should not be given to patients who are taking monoamine oxidase
(MAO) inhibitors for depression or to patients with high blood pressure because
it can cause dangerously high blood pressure elevations. Tyrosine may also
promote the growth of malignant melanoma by promoting the division of cancer
Amino acids should not be taken regularly; ingestion may inhibit the body's
natural production of these chemicals.
L-tyrosine (200 and 400 mg/kg) significantly potentiated the anorexigenic
effects of phenylpropanolamine (5, 10, or 20 mg/kg), ephedrine (5, 10, or 20
mg/kg), and amphetamine (0.75, 1.25, or 1.75 mg/kg) in a dose-dependent manner
in rats (Hull and Maher 1990). More research is needed to determine whether
L-tyrosine supplementation would produce similar results in
Levodopa (L-dopa) may decrease tyrosine and tryptophan levels (Riederer
1980). However, administering L-dopa with tyrosine may decrease absorption of
the amino acid by competitively inhibiting the transport system (Awad
L-tyrosine increased morphine-induced analgesia 154% in mice; only the L-form
of tyrosine produced these effects (Hull et al. 1994). Further studies are
needed to determine whether L-tyrosine would potentiate the analgesic activity
of morphine in humans.
Awad AG. Diet and drug interactions in the treatment of mental illness
– a review. Can J Psychiatry.
Balch JF, Balch PA. Prescriptions for Nutritional Healing. 2nd ed.
Garden City Park, NY: Avery Publishing; 1997:42.
Haas EM. Staying Healthy with Nutrition. Berkeley, Calif: Celestial
Hull KM, Maher TJ. L-Tyrosine potentiates the anorexia induced by
mixed-acting sympathomimetic drugs in hyperphagic rats. J Pharmacol Exp
Hull KM, Tolland DE, Maher TJ. L-tyrosine potentiation of opioid-induced
analgesia utilizing the hot-plate test. J Pharmacol Exp Ther.
Mindell E, Hopkins V. Prescription Alternatives. New Canaan, Conn:
Keats Publishing; 1998:398.
Riederer P. L-Dopa competes with tyrosine and tryptophan for human brain
uptake. Nutr Metab. 1980;24(6):417-423.
Shealy CN. The Illustrated Encyclopedia of Healing Remedies.
Shaftesbury, England: Element; 1998:269.
Werbach MR. Nutritional Influences on Illness. New Canaan, Conn: Keats
Copyright © 2000 Integrative Medicine
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