As long as it doesn’t make you jittery or interfere with sleep, three cups of coffee is not too much.

In fact, it's actually quite amazing how many studies have shown that drinking coffee might be good for your health. Prior studies have shown a link between coffee drinking and a lower risk of developing certain diseases, like:

• Stroke
• Kidney stones
• Cirrhosis of the liver
• Type 2 diabetes

Coffee drinkers also have a lower death rate. But it may not be the coffee that extends life. I think it’s something else about coffee drinkers that allow them to live longer.

There are potential downsides to drinking too much coffee. In some people, it can raise blood pressure. For instance, teenagers seem to be more likely to have higher blood pressures from caffeine.

Coffee also can interfere with how well your body absorbs iron and calcium. But it’s not the caffeine that causes this. It’s related to another ingredient in coffee called phenolic acid. So even decaf coffee with cause your body to absorb less minerals. But you need to drink a lot of coffee for it to greatly lower the amount of iron and calcium in your bloodstream.

Depending on how you make your coffee, it can raise cholesterol levels a little. Again, it's not the caffeine that influences cholesterol levels. It's the "coffee oil" from the bean.

If you boil or press your coffee, then the coffee oil gets into the brew. However, today most coffee in the United States is filtered through paper. Filtered coffee does not raise total cholesterol or LDL ("bad”) cholesterol.

There's probably some amount of coffee and other drinks containing caffeine that carries a risk of real health hazards. I am still unclear as to what that level is for an otherwise healthy adult.

My advice to patients is practical. If even one cup of coffee makes you jittery,  anxious, or interferes with sleep —  then that is one cup too many for you. I am honest with my patients. I don't know if 10 cups of coffee per day is too much. I would not drink that much. Three cups per day is my own limit.