The relationship between coffee consumption and serum cholesterol under consideration of smoking history.

A large German population sample of 6820 men and 7258 women was used to investigate the relationship between coffee consumption, total serum cholesterol and HDL cholesterol. Analyses were conducted on men and women separately. Differences in age, body mass index, diastolic blood pressure, smoking habits, alcohol, fish, milk and tea consumption, physical activity and medication use were controlled for in the analyses. Interactions between coffee consumption and smoking habits in their relationship with serum cholesterol were part of the analyses. For men, a positive relationship between coffee consumption and total serum cholesterol was found among smokers and life-long abstainers but not in the group of ex-smokers. In women a relationship between coffee consumption and total serum cholesterol was also present, but very weak (only statistical significant in covariance analyses). Levels of HDL cholesterol did not correlate with coffee consumption in either men and women. Hypotheses concerning the peculiarities of the group of ex-smokers are developed, and supporting empirical evidence is given. It is suggested that the group of ex-smokers should always be analysed separately.