A little coffee may slow your heart rate.
Drink some coffee and your blood pressure may rise a little. Your heart reacts to this drop in pressure by slowing slightly. However, if you keep drinking beyond a cup or so, the heart is likely to accelerate.
Coffee drinking can exacerbate stomach ulcers.
Stomach ulcers can be excruciatingly painful. Coffee can do a number on the lining of your gastrointestinal tract, giving rise to ulcers and other forms of gastric irritation and damage. If you have an ulcer, you may be best off forgoing coffee until the situation has improved. Think you’re too young to worry about ulcers and all that other stuff? Then you better read the foods to never eat after 30 and then read up on Becoming Ageless.