Writing in the New England Journal of Medicine, Dr. Neal Freedman and colleagues examined the association of coffee drinking with later total and cause-specific deaths among 400,000 people.
Freedman et al. noted that caffeine was generally regarded as unhealthy, but that antioxidants and other bioactive compounds, and other studies had shown inverse associations between coffee drinking and serum biomarkers of inflammation, as well as insulin resistance.
But the team noted that coffee had been linked to an increased risk of heart disease (Lancet 1972;2:1278-81), since it was associated with increased low-density lipoprotein cholesterol levels and blood pressure increases, but that the results of studies were inconsistent and confounders such as smoking were not properly controlled.
Coffee and smoking
For this study, participants were drawn from the National Institutes of Health (AARP Diet and Health Study) in 1995/1996 and were 50 to 71 years old at baseline – those with cancer, heart disease and a stroke history were excluded – and completed lifestyle, dietary and demographic questionnaires.
During a follow-up until the date of death or December 31, 2008 (whichever was sooner) 33,731 men and 18,784 women died. In age-adjusted models the risk of death increased among coffee drinkers.
“However, coffee drinkers were also more likely to smoke and after adjustment for tobacco-smoking status and other potential confounders, there was a significant inverse association between coffee consumption and mortality,” Freedman et al. wrote.
Coffee drinkers were also more likely to drink more than three alcoholic drinks a day, consume more red meat, have a lower level of education, took less physical activity and ate less fruit and vegetables.
Inverse associations were observed for coffee drinkers and deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes and infections, but not for deaths due to cancer.
For instance, compared to non-coffee drinkers, men who drank six or more cups of coffee per day had a 10% lower risk of death, whereas women in the same category had a 15% lower risk.
‘Reassurance’ for coffee drinkers
Questioned about the significance of his research, Dr. Neal Freedman told BeverageDaily.com “As an observational study, we cannot determine whether coffee itself was responsible with less risk of death over the course of our study.
“However we believe that our findings have some reassurance for coffee drinkers. Additional work is needed in this area, as there are many compounds in coffee and whether and these compounds affect health remains to be established.”
Freedman said the team accounted for the other factors associated with coffee drinking “as best we could; however there may have been other exposures for which we could not account which may have been responsible for the association”.
Title: ‘Association of Coffee Drinking with Total and Cause-Specific Mortality’
Authors: N.Freedman, Y.Park, C.C Abnet, A.R Hollenbeck, R.Sinha
Source: The New England Journal of Medicine (2012: 366: 1891-1904, May 17 2012)