L-tyrosine: The amino acid for more stress resistance
General information about L-Tyrosine
L-tyrosine is a non-essential amino acid. This means that it is contained in many proteins and, unlike essential amino acids, can be produced by the body itself.
The synthesis product is formed as a precursor of L-phenylalaninine in the healthy liver.
Additional intake is only necessary in certain situations, e.g. when demand is increased by stress or illness, or when production is limited due to liver disease. Additional L-tyrosine can also make sense during high athletic stress.
Commercially, L-tyrosine is available as a supplement in capsules, tablets, granules, and water-soluble powder.
The formation of dopamine can Tyrosine improve thinking performance, reaction speed and concentration. In addition, it seems to make people more stress-resistant and reduce stress in extreme situations such as severe mental and physical stress.
Most studies evaluating the effects of L-tyrosine in the past have been based on research conducted by the US Army Research Institute and other Army institutes. The studies have mainly focused on cognitive aspects during stressful situations for the body such as cold, heat and hypoxia.
In one of the more recent studies, conducted in 2007, the U.S. Army investigated whether tyrosine could improve physical performance.
For this purpose, 15 subjects first had to complete a control test in warm water and then twice immerse in a cold water pool with an interval of one week. After the water bath, they had to solve brainteasers and prove themselves at a shooting range.
Before both runs, subjects were given either a bar containing tyrosine (300 mg/kg body weight) or a placebo.
In the experiment without tyrosine, the participants’ body temperature dropped by an average of 1.6 degrees due to the cold water. In the experiment with a placebo, the participants also performed 18% worse on the thinking tests and 14% percent worse on the shooting test due to the lower body temperature than after the warm test bath at the beginning.
The interesting thing was that if the test subjects had taken tyrosine in advance, no negative effects on performance in the tests with cold could be detected.
The conclusion that an additional intake with tyrosine can be effective was also reached by other comparable studies.
A very similarly designed study, in which subjects also completed a dive in mild (35 degrees) and cold (10 degrees) water temperatures, also found, that the placebo study participants who had to enter cold water not only subjectively experienced more stress.
They also had more stress hormones, cortisol levels, released. In contrast, participants who had ingested tyrosine prior to their dive into the 10 degree cold water showed no difference in performance compared to the warm water dive.
How can the effect of L-tyrosine be explained?
The amino acid tyrosine is, so to speak, the precursor of the so-called natural catecholamines Dopamine and adrenaline. Here, dopamine serves mainly as a neurotransmitter and is known to keep the brain efficient.
Cold weather can cause a deficiency of these catecholamines. Taking L-tyrosine is able to prevent this catecholamine deficiency.
Some studies have further found that in stressful situations, where norepinephrine (a neurotransmitter produced in the medulla of the adrenal gland as well as in the nervous system, and also a member of the catecholamines) exerts a protective effect, the supply of L-tyrosine appears to provide a kind of “safety buffer” of building blocks.
This buffer can prolong the anti-stress effect of catecholamines by delaying their breakdown.
To date, there is no intake recommendation from the GermanGerman Nutrition Society (DGE) for L-tyrosine.
Studies that have tested an anti-stress effect of L-tyrosine used a dosage of 100 to 150 mg/kg body weight, which can be taken 60 minutes before exercise.
For higher amounts of, for example, 300 mg/kg body weight, it is advisable to take two doses with an interval of four hours.
Good natural sources of tyrosine are peanuts, peas, soy products, and meat and cheese.