The Caffeine Debate

Some of you may already have seen, though I just saw this week:

Researchers in Switzerland found that drinking coffee can limit blood flow to the heart while exercising.

The caffeine in just two cups of coffee can prevent the heart from getting the amount of oxygen needed during physical activity, reports HealthDay.

"Whenever we do a physical exercise, myocardial blood flow has to increase in order to match the increased need of oxygen. We found that caffeine may adversely affect this mechanism. It partly blunts the needed increase in flow," says Dr. Philipp A. Kaufmann, of the University Hospital Zurich and Center for Integrative Human Physiology.

The scientists studied 19 people who were daily coffee drinkers. Thirty-six hours prior to the study, the participants did not ingest any caffeine. PET scans were used to measure their heart blood flow before and after exercising.

The caffeine did not affect blood flow in those who did not exercise. However, participants who took caffeine tablets before exercising were shown to have a 22 percent slowdown in heart blood flow.

The study appears in the Jan. 17 issue of the Journal of the American College of Cardiology.