I've seen reports that a mild coffee habit greases the workplace and makes people more productive and, in some cases, more creative. While the reports came from food companies that control the coffee bean market, there's some truth in them. The report didn't associate blood pressure and cholesterol with caffeine, but both are affected adversely by high coffee consumption. There may be other problems as well for people who drink coffee excessively. On the positive side, a cup of black coffee contains only three calories, has no cholesterol and only a trace of fat.
Coffee also has a smattering of nine minerals, two vitamins and carbohydrates.