In stress situations in specific regions of the brain, the turnover of norepinephrine is rising and its absolute level decreases. Animal studies have shown that tyrosine, when taken abruptly or through diet, protects them from the neurochemical and behavioral effects caused by acute stressors. Tyrosine is a large amino acid found in dietary proteins and is a precursor to norepinephrine, dopamine and epinephrine.
In stressful cases the highly active catecholaminergic neurons may require a higher precursor concentration such that the catecholamine composition is in equilibrium with the increased amounts of neurotransmitters secreted. Specifically, noradrenergic neurons affect attention, efficacy, motor activity and anxiety. Therefore, tyrosine may have a role in protecting against the undesirable behavioral effects induced by acute stress by preventing the depletion of norepinephrine in these neurons.
A research conducted in the US and published in the Brain Research Bulletin Journal has examined whether tyrosine can have beneficial effects in people exposed to sudden stressful conditions such as cold and hypoxia.
23 soldiers aged 18-20 years participated in this test and all were twice exposed to two levels of environmental stress, mild and severe cold and hypoxia conditions with high humidity levels and high altitude. There was also a control status at normal temperature and pressure conditions. All participants were also tested with placebo and taking tyrosine with compensated doses for all three environmental conditions and was exposed for about 4.5 hours a day.
Tyrosine or placebo was taken in capsules in two equal doses, each capsule containing 300mg of tyrosine. The first dose (50mg / kg) was obtained before exposure to the stressful environment and the second (50mg / kg) 40 minutes later, with the total dose accounting for 80% of the recommended daily intake.
Participant’s symptoms, mood, cognitive behaviour, reaction time and vigilance have been observed, as cold and high altitudes are environmentally diverse and have adverse effects. The participants were asked to fill out questionnaires for their symptoms and their mood, and tests for cognitive function.
From the test results, as expected each participant was affected differently from exposure to environmental stress. Tyrosine has greatly reduced the impact on behavior from exposure to environmental stress, cold and hypoxia. Also, administration of tyrosine reduced symptoms of headaches, cold, anxiety, fatigue, muscle weakness and sleepiness compared placebo. It seemed that tyrosine supplementation reduced dizziness, confusion, unhappiness and tension, and the participants said they could think more clearly.
Expected exposure to cold and hypoxia increases environmental stress and reduces cognitive function. However, it appeared that administration of tyrosine reduced many of the symptoms of reduced cognitive function.
Tyrosine appeared to be able to reduce adverse effects from exposure to environmental stress, especially in cases of severely impaired catecholaminergic activity, as further research is required for the beneficial action of tyrosine in other stressful conditions.
Banderet, L.E and Lieberman, H.R. (1989). Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Brain Research Bulletin, 22:759-762
: Neuro Balance