Acetyl-L-Carnitine (ALC) is involved in the production of cellular energy in the mitochondria.5 Magnesium from Meta Mag® provides support for fatigue and lethargy.6 A placebo-controlled, blinded study showed that 2 g of ALC daily helped to improve mental fatigue thus assisting healthy cognitive function in older people.7 ALC's affinity for mental fatigue has been demonstrated in a clinical study comparing different forms of carnitine against symptoms and serum levels of carnitine. It showed that ALC serum levels correlated with changes in mental fatigue as contrasted with other forms of carnitine which only assisted general fatigue.8
Thyroid hormone requires iodine, selenium and zinc for synthesis and activation. Peripheral conversion of thyroxine (T4) into the more physiologically active tri-iodothyronine (T3) is dependent on tyrosine and iodine.3,9,10
Neurotransmitters involved in basal metabolic rate, cellular metabolism and oxygen utilise tyrosine in their synthesis.11 A double blind randomised trial using 2 g of tyrosine per day in army cadets suggested that supplementation with tyrosine may modulate the effects of stress and fatigue on cognitive task performance.12