Coffee, black gold, 'poison of choice'. Whatever you call it, it is the world's second most popular non-water beverage (second only to all forms of tea combined) and consumed world-wide.
Coffee can be seen as a nutritional product as it is a mixture of many nutriceutical compounds that all have individual purposes. Coffee can also exert effects like any supplement or drug and rival some of them in potency. It is not just an inert food product, coffee is a supplement.