400 mg is the maximum amount of daily caffeine intake that does not have a negative effect on fluid balance.
A methylxanthine class stimulant, caffeine stimulates the central nervous system. It is employed as a cognitive enhancer to improve alertness and attentional function. In order to increase the release of the neurotransmitter acetylcholine, caffeine works by preventing adenosine from attaching to the adenosine A1 receptor.
Through nonselective inhibition of phosphodiesterase, caffeine also raises levels of cyclic AMP.
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