Studies examining the association between coffee consumption and risk of myocardial infarction (MI) have been inconclusive, according to background information in a current JAMA article. Caffeine is metabolised primarily by the enzyme cytochrome P450 1A2 (CYP1A2) in the liver.
Ahmed El-Sohemy, Ph.D., of the University of Toronto, and colleagues conducted a study to determine whether gene variations of CYP1A2 modifies the association between consumption of caffeinated coffee and risk of nonfatal heart attack. Fifty-five percent of the cases (n = 1,114) and 54 percent of controls (n = 1,082) were carriers of the slow *1F allele. For carriers of the slow *1F allele, those who drank 2 to 3 cups of coffee a day had a 36 percent increased odds of heart attack; those who drank four or more cups per day had a 64 percent increased odds of heart attack. Corresponding consumption for individuals with the rapid *1A/*1A genotype resulted in the reduced odds of heart attack by 22 percent and one percent, respectively.
Among the slow metabolisers, younger individuals showed an increased risk. The risk associated with drinking four cups/d or more compared with less than one cup/d increased from 2-fold for individuals younger than 59 years to more than fourfold for those younger than 50 years. Among the fast metabolisers who were younger than 59 years of age, those who drank one cup/d or two to three cups per day had a reduced odds of a heart attack by 52 percent and 43 percent, respectively.
"In summary, consistent with most case-control studies, we found that increased coffee intake is associated with an increased risk of nonfatal MI. The association between coffee and MI was found only among individuals with the slow CYP1A2*1F allele, which impairs caffeine metabolism, suggesting that caffeine plays a role in the association," the authors conclude.
MEDICA.de; Source: JAMA and Archives Journals