L-methionine is a precursor to S-adenosylmethionine (SAMe). SAMe is directly involved in methylation processes including catecholamine synthesis. L-tyrosine is a precursor to catecholamines including dopamine, norepinephrine, and epinephrine. L-histidine is a precursor to histamine, which plays an important role in the release of pituitary hormones and wakefulness. Rhodiola rosea root extract is an adaptogen that has been shown to reduce stress-induced effects. In a randomized, double-blind, placebo-controlled study, Rhodiola rosea was shown to significantly reduce mental fatigue and improve general well-being under stress. Green tea leaf extract has the polyphenol Epigallocatechin gallate which provides antioxidant protection by its ability to scavenge free radicals and metal ions. It has been shown to increas resistance to fatigue in vivo. Vitamins B and C are active forms of pantothenic acid, niacin, B6, folate, B12 and C. These are important for the synthesis of adrenal hormones and neurotransmitters.