Coffee Ingredient Beyond
Caffeine May Affect Heart
Excerpt By Alison McCook, Reuter's Health

NEW YORK (Reuters Health) - The mysteries hidden inside a coffee cup may be more multi-layered than many realized, results from a small study suggest.

Dr. Roberto Corti of the University Hospital in Zurich, Switzerland, and his colleagues found that something other than caffeine may also affect the cardiovascular systems of coffee drinkers. And for habitual drinkers, another ingredient may eventually suppress some of caffeine's effects.

Corti explained to Reuters Health that coffee contains several hundreds of ingredients, and the current findings demonstrate that "there is something else that has some activity in our system."

Just what coffee does to the cardiovascular system remains unclear, Corti and his team note in the rapid access issue of Circulation: Journal of the American Heart Association for December 3rd. Previous research has found that drinking coffee can cause a slight increase in blood pressure in some, while some studies have shown the beverage has no effect on blood pressure or can actually reduce it.

In the current study, Corti and his team investigated the effects of regular and decaffeinated coffee on six regular coffee drinkers and nine others who said they opted for coffee only on occasion.

The investigators found that the blood pressures of occasional coffee drinkers rose after they drank coffee, while regular consumers experienced no blood pressure increase after drinking coffee. Both groups showed similar increases in the levels of activity of their sympathetic nervous systems, a body component that helps regulate blood pressure and heart rate.

Occasional drinkers also showed a blood pressure increase after drinking decaffeinated coffee--a finding that suggests the beverage contains an ingredient besides caffeine that could affect cardiovascular health, Corti told Reuters Health.

But could the bodies of occasional coffee drinkers simply be reacting to the taste of decaf coffee, associating it with caffeine and responding as they would to regular coffee? Not likely, Corti said. Along with an increase in blood pressure, these participants also experienced a jump in the activity of their sympathetic nervous systems that lasted for 60 to 90 minutes, Corti noted, and such an extended change is difficult to explain by the previous phenomenon, known as the placebo effect.

To explain why the blood pressure of regular coffee drinkers didn't jump after a cup of java, Corti suggested that something may suppress the effect of caffeine on blood pressure--either an ingredient in the coffee or a change that occurs in the bodies of regular drinkers.

Additional experiments revealed that while regular coffee drinkers may develop some type of tolerance to the beverage, it is not to the caffeine, Corti noted. When the researchers administered an IV that contained caffeine or placebo and didn't tell participants what they received, both groups had a similar increase in blood pressure and sympathetic nervous system activity after an IV of caffeine. None responded to the placebo IV.

In an interview, Corti said the findings don't suggest people who drink coffee should stop in order to protect their cardiovascular health, although the study did not examine the effects of heavy coffee drinking on blood pressure and nervous system activity. For those who drink one cup a day or so, the beverage is reasonably safe, the researcher said.

SOURCE: Circulation 2002;106:2935-2940.

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