Absorption By The Body
Haemoglobin Major Blood Component
Caffeine is rapidly and completely absorbed into the blood stream, the haematic concentration is highest after 15 to 45 minutes. It is then biotransformed by the liver before being expelled by the kidneys and urinary tract. The half life of caffeine in the blood stream varies significantly; in an average male it would be between 4 and 6 hours, in a pregnant women or those taking the contraceptive pill it may take up to 12 hours. Caffeine, like other alkaloids, is particularly harmful for people with ulcers, heart disease and hypertension.