Amino acids are building blocks of protein. L-tyrosine is a non-essential amino acid, meaning you don't need to obtain it from diet as long as you consume enough L-phenylalanine, which the body converts to tyrosine. Because L-tyrosine appears to have particular benefits for mental health and mental performance, many people choose to take supplements of this amino acid or eat more food containing it, such as meat, seafood, dairy products and whole grains. Acetyl-L-tyrosine is a type of L-tyrosine supplement that the body converts to tyrosine. Consult a qualified health care provider before taking acetyl-L-tyrosine supplements.
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Acetyl-L-tyrosine is more rapidly absorbed and has better bioavailability than L-tyrosine supplements, so less of it is lost through urine. In addition, you can take a smaller dose of acetyl-L-tyrosine to obtain the same effects of a larger dose of L-tyrosine. This is beneficial, because large doses of L-tyrosine can cause irritability, restlessness, anxiety and abnormal heart rhythms, according to physician Ray Sahelian, who specializes in natural supplements.
Most brain neurotransmitters are made from amino acids, and L-tyrosine is important for the formation of epinephrine, norepinephrine, dopamine and serotonin, according to the University of Maryland Medical Center, or UMMC. These neurotransmitters are important for regulating mood and behavior, and acetyl-L-tyrosine or L-tyrosine supplements also can enhance mental alertness. L-tyrosine may provide benefits for people with attention deficit disorder, but the effects appear to last only a couple of weeks, according to the Swedish Medical Center.
Alertness After Sleep Deprivation
Tyrosine supplements also may improve mental function and memory, as well as relieve fatigue, in sleep-deprived persons, according to the Swedish Medical Center. The Center cites a study with 20 U.S. Marines who were deprived of sleep for one night and then checked for alertness throughout the following day. Supplements of 10 to 15 g of tyrosine appeared to increase alertness for about two hours.
Performance Under Stress
Some research with tyrosine supplements indicates that they improve memory and cognitive performance in humans and animals while they are experiencing psychological stress, according to the UMMC. A study published in the January 15, 1999 issue of "Brain Research Bulletin" evaluated the effects of tyrosine on cognitive task performance by 10 participants in a demanding military combat training course likely to cause stress and fatigue. These individuals showed better performance on a memory and a tracking task than a group taking a placebo. Tyrosine supplementation also decreased systolic blood pressure.