Coffee contains hundreds of components including substantial amounts of chlorogenic acid, caffeine, magnesium, potassium, vitamin B3, trigonelline, and lignans.
Chlorogenic acid has been shown in animal experiments to reduce glucose concentrations; coffee also contains tannin, which is beneficial for heart and arteries.
Researcher Dr. Rob van Dam of the Harvard School of Public Health, says that coffee, if taken in moderate amounts, can actually prevent colon, liver and rectal cancer.