Study Conflicts With Others; More Data Sought : Higher Cholesterol in Women Coffee Drinkers
A UC San Diego medical school study of coffee drinkers in Rancho Bernardo has found higher cholesterol levels in women--but not in men--as a result of moderate coffee consumption, the authors reported this week. High blood cholesterol can bring increased risk of heart disease.
The results, unexplained so far, conflict with other studies on the link between coffee and cholesterol, according to Cedric Garland, a co-author of the study and assistant professor at the school. As a result, Garland and the study’s three other researchers in the community and family medicine department have called for additional experiments to try to determine the precise relationship.
The UCSD study looked at data from 381 men and 320 women living in Rancho Bernardo between 1972 and 1974. The study is part of a National Heart, Lung and Blood Institute program examining cholesterol and its relation to long-term health among Rancho Bernardo residents.
The data showed that women drinking four or more cups of coffee a day had cholesterol levels significantly higher than women who drank no more than one cup a day. The higher levels were exhibited even after researchers accounted for age, obesity, smoking, total dietary fat intake, exercise and alcohol.
The data also showed that the increased cholesterol was due almost entirely to an increase in low-density lipoproteins, fatty packets that contribute to the development of atherosclerosis, or hardening of the arteries.
No significant relationship was found between levels of coffee drinking and cholesterol levels in men.
The study showed that decaffeinated coffee had no effect on blood cholesterol in either men or women, which Garland said could indicate that caffeine causes the effect in women.
“This study appears to indicate that for active women who consume moderate amounts of saturated fats, drinking four or more cups of coffee may significantly elevate blood cholesterol,” Garland said in a prepared release. “Heart disease, America’s No. 1 health problem, is directly associated with cholesterol levels, so the increased risk could be significant.”
The study appears in the June issue of the American Journal of Epidemiology, published by the Johns Hopkins University School of Hygiene and Public Health in Baltimore.
Garland cautioned that the Rancho Bernardo study conflicts with several of the dozen or so studies done in various parts of the world on the coffee-cholesterol relationship. For example, a major study done in Framingham, Mass., from the so-called Framingham Heart Study begun in 1949, has found no evidence that coffee contributes to atherosclerosis. That study refuted previous work that showed a link but had been heavily criticized for not factoring in use of tobacco, since coffee drinkers are considered more likely to smoke cigarettes.
However, a major research project in Norway published in 1983 showed heavy coffee drinking does raise levels of blood cholesterol in men and women who drank nine cups or more a day, compared to those who drank one cup or less. This was true even after smoking, exercise and alcohol consumption were taken into consideration.
In addition, a Stanford University study completed earlier this year found a correlation between higher cholesterol levels and daily consumption of more than two cups of coffee among men, again adjusted for age, smoking, exercise and other environmental factors.
Mirroring the conflicting evidence, the Stanford researchers said their study showed only an association between coffee and cholesterol, not direct proof of cause and effect.