Tyrosine – Stimulating Amino Acid

Tyrosine in the brain is initially transformed into a compound known as levodopa (L-DOPA) through the operation of the enzyme tyrosine hydroxylase. Subsequently, levodopa undergoes decarboxylation, which is regulated by the enzyme L-amino acid decarboxylase. The removal of the carboxyl group results in the formation of the neurotransmitter dopamine. Dopamine is commonly associated with feelings of pleasure and excitement and occurs when we engage in something pleasurable. Dopamine and another neurotransmitter, serotonin, function antagonistically. When serotonin levels are elevated in relation to dopamine, sensations of drowsiness, fatigue, and decreased motivation to act arise. Conversely, when dopamine levels increase, such as through tyrosine supplementation, sensations associated with fatigue are reduced, and feelings of stimulation and excitement emerge. Dopamine can be further transformed into other neurotransmitters that also induce stimulation. The first step in its transformation is conversion into norepinephrine, a process regulated by the enzyme beta-dopamine hydroxylase. Norepinephrine can be further transformed into epinephrine. The last three compounds in this transformation process are often referred to as catecholamines and are recognized for their stimulating properties and their role in the famous fight-or-flight mechanism. In addition, they also play a very important role in fat loss through stimulation of adrenergic receptors located on fat cells and regulating lipolysis. It is worth noting that despite the stimulating effect and increased catecholamine levels, tyrosine supplementation of 100 milligrams per kilogram of body weight does not raise blood pressure, making it a good alternative for individuals with hypertension.

There is speculation that tyrosine supplementation prior to and during physical activity could influence the dopamine-to-serotonin ratio in the brain, leading to a decrease in central fatigue and improvement in fitness, particularly in sports characterized by long durations or high intensity. Several research teams have attempted to verify these speculations and have shown promising results. In 2011, a group of scientists discovered that tyrosine in a dose of 150 milligrams per kilogram of body weight helped to prolong the duration of endurance-based physical activity by 11%, which also translated into a larger number of calories burned. A more comprehensive review of the scientific literature reveals that the dosage of tyrosine plays a significant role in this context. In 2002, Chinevere et al. investigated the effects of tyrosine supplementation at a dose of 25 milligrams per kilogram of body weight in a group of cyclists, but found no significant results.

Increasing dopamine levels through the intake of tyrosine may also be advantageous beyond sports. Tyrosine is an excellent means of inducing the required stimulation during work, learning, or an exam. One analysis examined the effects of taking tyrosine on individuals suffering from sleep deprivation, which made it challenging for them to accomplish their tasks. Tyrosine helped mitigate the adverse effects of sleep deprivation and enhance research capabilities compared to the control group.

Tyrosine is available in various forms, but the most commonly encountered are tablet and powder. Many people take it in moderate amounts of 500 to 2000 milligrams, however, such doses are too small to have any significant impact. To improve cognitive functions and as a pre-workout form, it is recommended to take tyrosine in amounts of 100 to 150 mg/kg of body weight. This means that a person weighing 80 kilograms should take 8-12 grams of tyrosine per serving. Tyrosine in this range is safe and should not cause any adverse effects. The toxic dose of tyrosine is about 5000 mg/kg of body weight.