Caffeine Lowers Cardiovacular Risk -- for Some

NEW YORK, March 2 -- A few cups of coffee a day might perk up cardiovascular health for normotensive patients older than 65.

In fact, the more caffeine, the better, according to an analysis of prospective data from the first National Health and Nutrition Examination Survey (NHANES I) from 1971 through 1973 and its first follow-up study, conducted in 1982 through 1984.

People 65 and older who had four or more servings a day of caffeine -- in coffee, tea, cola, and chocolate -- had less than half the risk of dying of heart disease than did people who had less than half a serving, according to John Kassotis, M.D., of the State University of New York Health Science Center in Brooklyn.

But there was no benefit for people younger than 65, Dr. Kassotis and colleagues reported in the February issue of the Journal of Clinical Nutrition.

The finding has some biological plausibility, Dr. Kassotis and colleagues said, because older people are more likely to have hypotension after eating, which has been found to predict coronary events and total mortality.

Caffeine, on the other hand, tends to increase blood pressure so that "the protection against death from heart disease in the elderly afforded by caffeine is likely due to caffeine's enhancement of blood pressure," Dr. Kassotis said.

The researchers included 6,594 participants who were 32 to 86 during the first follow-up and had no history of cardiovascular disease at the beginning of the study.

They used data from that survey and the earlier NHANES study to analyze the participants' caffeine intake and other factors. Mortality data was obtained from subsequent NHANES follow-up surveys in 1986, 1987, and 1992.

The participants were grouped according to their caffeine intake -- less than half a serving a day and half to two, two to four, and four or more servings a day of coffee, tea, cola, and chocolate. The daily intake in those categories was estimated to be less than 30 grams, 30 to 100 grams, 100 to 350 grams and 350 grams or more.

Analysis found there were 426 cardiovascular deaths during the follow-up, which averaged 8.8 years.

Caffeine intake was inversely correlated with the risk of cardiovascular death, in a dose-responsive manner. Specifically, compared with those in the lowest intake group, the relative risk of death was:

• 0.77 (with a 95% confidence interval from 0.54 to 1.10) for those with an intake from half to two servings a day.
• 0.68 (with a 95% confidence interval from 0.49 to 0.94) for those with an intake from two to four servings a day.
• 0.47 (with a 95% confidence interval from 0.32 to 0.69) for those with an intake of four or more servings a day.
• The trend was statistically significant at P=0.003.

The researchers also broke cardiovascular death into cerebrovascular (including cerebral hemorrhage and thrombosis) and non-cerebrovascular death, which included everything else.

Analysis showed no effect for cerebrovascular deaths, but the pattern for non-cerebrovascular death was similar to the overall effect, Dr. Kassotis and colleagues found.

On the other hand, people older than 65 who had stage two or greater hypertension had no benefit from caffeine, the researchers said.

"If our findings are confirmed," the researchers said, "they may have important ramifications because caffeinated beverages are widely consumed, and heart disease is one of the leading causes of death in the elderly."

Because of its epidemiological nature, the study does not prove a cause-and-effect link between caffeine and lowered heart risk, the researchers said. Also, because of changes in NHANES population over time, it may not generalize easily to the population as a whole.

For these reasons, the authors concluded that the "study does not provide a valid basis for recommending increased consumption of caffeinated beverages. Our findings require confirmation in future epidemiologic, metabolic, and clinical trial studies."