Common Name: Tyrosine
Synonyms: L-tyrosine

Overview:

Tyrosine is classified as a conditionally essential amino acid. Although under normal circumstances the body can make all of the tyrosine that it needs, when certain conditions such as phenylketonuria exist, tyrosine must come from dietary sources. L-tyrosine is manufactured in the body from phenylalanine and is found in soy, chicken turkey nuts, dairy, legumes (beans and peas), avocados, bananas and pumpkin seeds.

Tyrosine, as with all amino acids, is involved in protein synthesis. Protein synthesis is not the only role it plays. Tyrosine is a precursor of not only the thyroid hormones thyroxine and triiodothyronine but the fight or flight hormone, epinephrine as well as the neurotransmitters, norepinephrine and dopamine. Tyrosine is also used by the body to manufacture melanin, the substance that gives hair and skin their color.

Tyrosine also has the ability to bind unstable free radicals and is considered to be a mild antioxidant. Because of its antioxidant capabilities, tyrosine may be helpful for people who have been exposed to harmful chemicals (such as from smoking) or radiation.

Low levels of tyrosine have been associated with:

1. Low blood pressure
2. Low body temperature
3. An under active thyroid
4. Depression
5. Edema
6. Fatigue
7. Lethargy
8. Liver damage
9. Loss of pigment of the hair and skin

Benefits

Tyrosine is essential in those who suffer from phenylketonuria (a genetic condition where people cannot metabolize phenylalanine). By eliminating all sources of phenylalanine, the brain damage and mental retardation that results can be avoided. The tyrosine deficiency that develops is because phenylalanine is necessary for the manufacture of tyrosine.

Preliminary studies of tyrosine’s benefits have shown that:

1. Tyrosine may help in the body’s ability to handle stress. This is because of the fact that it is the precursor for epinephrine and norepinephrine, the body’s two main stress related hormones. Taken ahead of time, tyrosine can help some people ward off the body’s reactions to such stressful situations as surgery, emotional upset, and sleep deprivation. A small study of marines showed that they were better able to handle and recovered faster from sleep deprivation when they took supplements of tyrosine.
2. In combination with conventional treatment, tyrosine appears to help in the successful treatment of cocaine abuse and withdrawal. It is usually used in conjunction with tryptophan (an essential amino acid) and imipramine ( an antidepressant). It has also proven helpful in caffeine and nicotine withdrawal.
3. Tyrosine may be helpful in the treatment of depression as tyrosine levels are often low in people who suffer from depression. Early studies showed that when used in conjunction with 5-HTP (5-hydroxytryptophan). However, more studies are needed to confirm the benefit of tyrosine supplements in the treatment of mild to moderate depression.
4. Tyrosine may prove helpful in the treatment of vitiligo (depigmentation of random areas of skin). This is an assumption made because tyrosine is involved the making of melanin and the fact that phenylalanine and ultra violet light are used to treat this condition.
5. Because tyrosine is a precursor to dopamine and preliminary studies have shown that tyrosine can cause an increase in the levels of dopamine in the brain, it has been speculated that tyrosine may be helpful in the treatment of Parkinson’s disease. This theory however has never been proven.
6. Body builders supplement with tyrosine in order to better tolerate stress and to increase muscle mass. These uses however have never been studied.

Recommended Dosage:

1. Therapeutic doses range from 7-30gms daily
2. This dosage should be divided into three doses taken 30 minutes before a meal
3. Doses of tyrosine should also be taken with a multivitamin tablet as vitamin B6, folate )B9) and copper are helpful in converting tyrosine into the neurotransmitters, norepinephrine and dopamine.
4. Total dietary intake of tyrosine should never exceed 12,000mg
5. Children who need supplementation of tyrosine should do so only under the direct care of their healthcare practioner.

Precautions

1. Those who suffer from migraine headaches should avoid tyrosine. It has been known to trigger migraine headaches and gastrointestinal upset in those who suffer from this condition.
2. tyrosine taken with MAOIs, antidepressant medications like phenelzine, tranylcypromine, pargyline and selegiline, may cause a severe increase in blood pressure. This hypertensive crisis can lead to a heart attack or stroke. Because of this people who are taking MAOI’s should avoid tyrosine supplements and even foods that contain a high amount tyrosine.
3. In animal studies, tyrosine increased the appetite suppressing effects of several medications including phenypropanolamine, ephedrine and amphetamine. Human studies are now needed to see if this characteristic of tyrosine is also seen in human beings.
4. Again animal studies have shown that tyrosine increases the pain relieving effects of morphine.
5. Levodopa (a medication used to treat Parkinson’s disease) may interfere with the absorption of tyrosine.
6. Those who suffer from melanoma should avoid tyrosine
7. Those with inborn errors of metabolism such as alkaptonuria and tyrosinemia type I and II should not take tyrosine

Women who are pregnant or breastfeeding should consult a health care provider before using any supplements. The affects of this supplement has not been tested on children and those suffering from liver or kidney disease. It is recommended that in people with liver or kidney disease this supplementation not be used.

Web References

1. http://www.umm.edu/altmed/ConsSupplements/Tyrosinecs.html
2. http://healthlibrary.epnet.com/GetContent.aspx?token=e0498803-7f62-4563-8d47-5fe33da65dd4&chunkiid=21794
3. http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/lty_0256.shtml

Printed Reference Material

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