Question: how much caffeine can body absorb?
Answer: Caffeine Metabolism: From the First Sip It only takes about 45 minutes for 99% of the drink's caffeine to be absorbed through these membranes/organs. In humans, the half-life for caffeine is anywhere from 4 to 6 hours on average, which explains why the average energy drink or coffee's effects last about 4 to 6 hours.