Coffee and High Blood Pressure

Coffee may well be the most misunderstood food item - right up there with shellfish and eggs. People assume it's bad for them - specifically, that it's bad for their heart - when the available evidence simply doesn't bear that out. For example: it doesn't appear to cause atrial fibrillation, even in those who already have had incidents of a-fib. Drinking more coffee doesn't increase your risk of high blood pressure (although caffeinated soda might). And in those over 65, drinking more caffeinated beverages means a lower risk of death from heart disease. Finally, drinking more coffee appears to protect you from type 2 diabetes.

The bad news, however, is that research on coffee and blood pressure has largely been limited to those who do not already have high blood pressure. Fortunately, a group of researchers in Spain noticed this and looked at 15 different studies of coffee and caffeine intake in order to evaluate the effect of coffee on those with mild to moderate high blood pressure (Am J Clin Nutr 2011;94(4):1113-26).

First they assessed whether blood pressures were increased by ingesting caffeine. In a grouping of eleven smaller studies including over 400 people with high blood pressure, the researchers found that yes, intake of the equivalent of 1.5 to 2 cups of drip coffee did indeed increase an individual's blood pressures for up to about 3 hours. However, this increase was not any greater than would be seen in those people with normal blood pressure.

They then looked at the effects of regular, long-term coffee drinking in nine different studies of those with high blood pressure, comparing such variables as a caffeine-free diet versus regular intake of caffeinated coffee as well as decaffeinated coffee versus regular cofeee. Again, those who already had high blood pressure did not see a long term increase in blood pressure when they were regular drinkers of caffeinated coffee.

Finally, the researchers looked at three studies that focused on the risk of death from cardiovascular disease in those with high blood pressure, finding that there was no increased risk of death associated with coffee or caffeinated beverages - although the results were mixed with regard to an increased risk of death from stroke.

What this means for you

Yes, coffee increases your blood pressure a small but significant amount, whether you already have high blood pressure or not. This short term increase in blood pressure is going to be more of a risk for those whose blood pressure is not well controlled, however. If you are drink caffeinated coffee regularly and you have high blood pressure that is well controlled, there doesn't appear to be any reason to stop drinking coffee. Indeed, the antioxidants found in coffee may help reduce the risk of heart disease even in those with high blood pressure.

Bottom line: if you have high blood pressure, talk to your doctor about your coffee intake. They may want you to pursue other lifestyle modifications, like losing weight, getting more exercise, or quitting smoking, before they recommend giving up your morning cup.

First posted: September 28, 2011