Caffeine is classified by the US Food and Drug Administration as generally recognised as safe (GRAS). Toxic doses, over 10 grams per day for an adult, are much higher than the typical dose of under 500 milligrams per day, A cup of coffee contains 80–175 mg of caffeine, depending on what “bean” (seed) is used and how it is prepared (e.g., drip, percolation, or espresso). Thus it requires roughly 50–100 ordinary cups of coffee to reach the toxic dose. However, pure powdered caffeine, which is available as a dietary supplement, can be lethal in tablespoon-sized amounts.
