A number of cohort studies have also been published since the early 1990s. In a cross-sectional study of 10,359 subjects in the Scottish Heart Health Study, it was found that non coffee drinkers had a significantly higher risk of coronary heart disease than the three categories of coffee drinkers (11). After 7.7 years of follow-up of this cohort, coffee consumption was associated with reduced risk of coronary morbidity and mortality although the statistical significance of these associations was marginal (12).
By contrast, a recent publication from the John Hopkins Precursors Study found that most categories of coffee consumption were significantly associated with increased risk of coronary heart disease, particularly heart attack, in smokers and non-smokers (13). However, in an editorial Willett argued that the author’s conclusions were not supported by their data and concluded that the results must have been due to chance (14).
Four subsequent cohort studies have not established any strong associations between coffee drinking and risk of coronary heart disease. A Norwegian cohort study of 38,500 subjects over 12 years found that coffee consumption was associated with increased risk of death from coronary heart disease but only when nine or more cups of strong Scandinavian coffee were drunk (15). In addition, if the first six years of follow-up were excluded, the association disappeared. A publication from the Nurses Health Study in the USA in which 712 cases of coronary heart disease were diagnosed in a cohort of 85,747 women over a period of ten years were unable to find any associations between coffee consumption or caffeine intake and risk of coronary heart disease (16).
In a cohort of 5,766 Scottish men followed up for 21 years there were no associations between coffee consumption and coronary heart disease mortality (17). In a Finnish cohort of 20,179 subjects followed up for 10 years, there were no significant associations between coffee consumption and the risk of nonfatal heart attack, coronary heart disease mortality or total mortality in men or women (18). Although not significant, the highest risks were found in the non-coffee drinkers.
St. Paul, Minnesota, USA
Rochester, New York, USA
United Kingdom, London