After as little as 10 minutes, the caffeine
concentration in your blood reaches half the maximum concentration,
which is enough to have an effect. The caffeine reaches maximum
levels, making you most alert after 45 minutes. Depending on how
fast or slow your body is able to break down the drug, you could
feel the effects of caffeine for 3 to 5 hours.
Coffee contains hundreds of different compounds. These include many
antioxidants that protect our bodies from damaging chemicals called
free radicals. These molecules cause aging and are associated with
illnesses such as cancer and heart disease. NIH studies show that
coffee drinkers have a reduced risk of Alzheimer's, Parkinson's,
type 2 diabetes and many other diseases.