Addictive Potential: None
Emergency Room Visits Yearly: No recorded hospital visits
Mandatory Minimum Sentence: None
Mechanism of Action: increases dopamine
Tyrosine, or 4-hydroxyphenylalanine, is one of the 20 amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word “tyrosine” is from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese.
Aside from being a proteogenic amino acid, tyrosine has a special role by virtue of the phenol functionality. It occurs in proteins that are part of signal transduction processes. It functions as a receiver of phosphate groups that are transferred by way of protein kinases (so-called receptor tyrosine kinases). Phosphorylation of the hydroxyl group changes the activity of the target protein.
A tyrosine residue also plays an important role in photosynthesis. In chloroplasts (photosystem II), it acts as an electron donor in the reduction of oxidized chlorophyll. In this process, it undergoes deprotonation of its phenolic OH-group. This radical is subsequently reduced in the photosystem II by the four core manganese clusters.
Tyrosine is a precursor to neurotransmitters and increases plasma neurotransmitter levels (particularly dopamine and norepinephrine) but has little if any effect on mood.
A number of studies have found tyrosine to be useful during conditions of stress, cold, fatigue, prolonged work and sleep deprivation, with reductions in stress hormone levels, reductions in stress-induced weight loss seen in animal trials, improvements in cognitive and physical performance seen in human trials. Because tyrosine hydroxylase is the rate limiting enzyme, however, effects are less significant than those of l-dopa.
Tyrosine does not seem to have any significant effect on mood, cognitive or physical performance in normal circumstances. A daily dosage for a clinical test supported in the literature is about 100 mg/kg for an adult which amounts to about 6.8 Grams at 150 lbs. The usual dosage amounts to 500-1500 mg per day (dose suggested by most manufacturers; usually an equivalent to 1-3 capsules of pure tyrosine). It is not recommended to exceed 12000 mg (12 g) per day. In fact, too high doses result in reduced levels of dopamine. Tyrosine may decrease the absorption of other amino acids in high or chronic doses. It decreases absorption of l-dopa.
Tyrosine appears to be a successful addition to conventional treatment for cocaine abuse and withdrawal. It may be used in conjunction with other amino acids such as tryptophan. Some individuals using tyrosine have also reported successful withdrawal from caffeine and nicotine.
It is also useful in alleviating the backend or hangover after MDMA use.