FRIDAY, June 18, 2010 (HealthDay News) -- Drinking coffee or tea in moderation reduces the risk of developing heart disease, and both high and moderate tea drinking reduces the risk of dying from the condition, according to a large-scale study from Dutch researchers.
The study, led by physicians and researchers at the University Medical Center Utrecht, examined data on coffee and tea consumption from 37,514 residents of The Netherlands who were followed for 13 years.
It found that people who had two to four cups a day of coffee had a 20 percent lower risk of heart disease compared to those drinking less than two or more than four cups a day. Moderate coffee intake also slightly -- but not significantly -- reduced the risk of death from heart disease and all causes.
Tea's performance was stronger on both counts. Drinking three to six cups of tea a day was associated with a 45 percent reduced risk of death from heart disease, compared to drinking less than one cup a day, and drinking more than six cups of tea a day was associated with a 36 percent lower risk of getting heart disease in the first place.
The apparent protective effects may be linked to antioxidants and other plant chemicals in the beverages, but how they work is unclear, according to researchers.
No effect of coffee or tea consumption on the risk of stroke was seen in the study.
Study authors found, however, that coffee and tea drinkers in The Netherlands had very different health behaviors, with more coffee drinkers smoking and having less healthy diets.
Dr. Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York City and a spokeswoman for the American Heart Association, noted that there has been ongoing controversy about the impact of daily tea and coffee consumption on health. "Here is another study that reaffirms there is no increased risk of heart disease and stroke, and in fact, when drinking coffee in moderation, there is possibly a reduction in your risk of heart disease," she wrote on behalf of the AHA.
Experts note, however, that it's too early to make specific recommendations on coffee and tea drinking for the sake of better health, despite a growing number of studies that suggest the beverages may help protect against heart disease.
"Based on current evidence, it is very difficult to come up with an optimum amount of coffee or tea for the general population," said Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health.
Discussing the study from The Netherlands in context of other research, Hu noted that this is not the first report on coffee and tea consumption and heart disease mortality. "Overall, the studies were consistent in showing that higher consumption of coffee did not increase the risk of morbidity or mortality from cardiovascular disease," he said. "Several suggested there might be a slight protective effect."
Those studies also suggested a protective effect of tea, Hu said, but "the problem with this is that different types of tea are consumed in different populations, so it is difficult to compare results in different studies." (Most people in the Dutch study reported using black tea).
Many people still have a lingering belief that coffee might be dangerous, because early studies suggested an increased risk of heart disease, Hu said. Some of those studies used self-reports from people after a heart attack, so there was a problem of "recall bias," Hu noted. "Certainly, moderate consumption is not likely to cause harm in terms of cardiovascular health," he concluded.
"Common sense should always prevail," said Dr. Arthur L. Klatsky, a senior consultant in cardiology at Kaiser Permanente Northern California and an adjunct investigator in its division of research, who led a previous study showing reduced incidence of heart rhythm abnormalities in coffee drinkers. "If you have unpleasant symptoms from caffeine, you should avoid it. Some people get insomnia even if they take it at noon."
But there is evidence that moderate coffee consumption is associated with a decreased risk of type 2 diabetes, Klatsky said.
One possible confounding factor is that people who drink moderate amounts of either coffee or tea tend to have a healthier lifestyle, exercising more and avoiding obesity, said Steinbaum.
Still, "this and other studies have shown that drinking two to four cups of coffee a day is associated with a 20 percent reduction in heart disease," Steinbaum said. When people ask her whether coffee drinking is dangerous, "my response is that drinking coffee is not unhealthy," she said.
The study was published online June 18 in Arteriosclerosis, Thrombosis and Vascular Biology.
More information on caffeine and heart disease can be found at the American Heart Association.