It's time once again for the Moment of Science Word of the Day. This is where we define a cool science term. Today's word is Homocysteine.

Homocysteine is an amino acid, and too much of it in your blood is bad news--it's been found to be a good indicator that heart attacks might be on the horizon. Unfortunately, drinking coffee has also been found to increase homocysteine levels.

It isn't clear whether caffeine is the issue or not. In a study done at Wageningen University in the Netherlands, one group of volunteers drank coffee while another took caffeine pills and a third group took placebos. Blood samples showed that caffeine-free people had the lowest homocysteine, caffeine-pill people the next highest, and coffee drinkers the highest of all.

Other chemicals in coffee seem to increase the boost caffeine gives to homocysteine. Coffee with a meal also seems to prevent the decrease in homocysteine that normally comes after eating. These aren't such big effects that otherwise healthy coffee drinkers need to worry about their hearts, but if you already have hypertension or artery problems . . . you might want to cut back. Of course, this is not the last word on this subject. So, as they say, stay tuned.