Tyrosine
Overview:
Tyrosine is a nonessential amino acid the body makes from another amino acid called phenylalanine. It is one of the essential compounds necessary for the production of several neurotransmitters in the brain including epinephrine, norepinephrine, and dopamine (reference 1). Tyrosine helps with organ function, specifically with organs responsible for making and regulating hormones (i.e. adrenal, thyroid, and pituitary glands) and is involved in the structure of almost every protein within the body. It also assists in the production of melanin, which is the pigment responsible for skin and hair color. For individuals who cannot use the amino acid phenylalanine (Phenylketonuria aka PKU), tyrosine is used in protein supplements. Tyrosine can also be found in soy products, chicken, turkey, fish, peanuts, almonds, avocados, bananas, milk, cheese, yogurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds.
Benefits:
Since tyrosine is related to the production of stress hormones Epinephrine and Norepinephrine, it has been associated with reducing stress levels. Tyrosine has been observed to be useful under not only stressful conditions, but situations of fatigue, prolonged work, cold and even sleep deprivation (reference 2). Some animal and human studies suggest that tyrosine supplements may help improve memory and performance under psychological stress (reference 3).
Tyrosine may also be beneficial for improving overall mood as well, through its relationship with the neurotransmitter Dopamine.
Side-Effects:
Tyrosine can trigger migraine headaches and stomach upset. It may also increase levels of thyroid hormone, so people with hyperthyroidism or Graves disease should avoid tyrosine.
Synergies:
Taking vitamins B6, B9 (folate), and copper along with tyrosine helps the body convert tyrosine into important brain chemicals.
Dosage:
Clinical studies have indicated that the upper consumption threshold is about 12g per day. Studies in humans used a dosage range of 100-150mg/kg bodyweight. To treat symptoms of sleep deprivation, one study used 150 mg per kilogram of body weight per day. Taking this supplement 60 minutes before any acute stressor (such as exercise) is recommended.
Further Reference:
1. http://umm.edu/health/medical/altmed/supplement/tyrosine
2. Neri DF, Wiegmann D, Stanny RR, et al. The effects of tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med 1995;66:313-9.
3. E Jongkees BJ, Hommel B, Kühn S, Colzato LS. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands--A review.