Coffee study quells myths
By Cam Wood
June 17, 2008 – Coffee drinkers often wonder if their daily cups of
brew are helping them health-wise or hindering them, and now they can
ponder a new study that adds to the stacks of medical literature on the
June 17, 2008 – Coffee drinkers often wonder if their daily cups of brew are helping them health-wise or hindering them, and now they can ponder a new study that adds to the stacks of medical literature on the subject.
Regular coffee consumption is not associated with a higher death rate in either men or women, according to findings published Monday in the Annals of Internal Medicine. The data were adjusted for age, smoking and other factors.
In fact, consumption of both caffeinated and decaffeinated coffee was associated with a "somewhat smaller rate of death" from heart disease.
"We found that coffee was inversely associated with total deaths – that means higher consumption of coffee was associated with lower risk of total deaths," said Esther Lopez-Garcia, who co-authored the paper while at the Harvard School of Public Health, and who is now an assistant professor of epidemiology at the University of Madrid.
"We need more studies that confirm that coffee consumption has a beneficial effect on health before recommending to consume coffee. However, we can say that to … coffee drinkers, that it's quite clear that coffee doesn't increase the risk of death," she said in an interview Monday.
The American groups studied were large – more than 41,000 men and more than 86,000 women in the Health Professionals Follow-up Study and the Nurses' Health Study. They reported on their coffee consumption, diet and other health-related behaviours every two to four years from 1986 to 1998 for the men and from 1980 to 1998 for the women. Participants were classified according to levels of coffee consumption until their date of death or June 1, 2004, whichever came first.
Women who consumed two to three cups of coffee per day had a 25 per cent lower risk of death from heart disease than those not consuming coffee, Lopez-Garcia said.
For men, this level of consumption was associated with neither a higher nor a lower risk of death during the followup period, the study said. There was no association between coffee drinking and cancer deaths.
The editors of the medical journal caution that the design of the study does not make it certain that coffee decreases the chances of dying sooner than expected.
"Something else about coffee drinkers might be protecting them," they note in a statement. "And some measurement error in the assessment of coffee consumption is inevitable because estimated consumption came from self-reports."
Ahmed El-Sohemy, a nutritional sciences professor at the University of Toronto, says the research suggests that "it's at least not bad news" for coffee drinkers.
"It seems like, overall, coffee doesn't seem to be, you know, making us drop like flies early on," said El-Sohemy, who wasn't involved in the research, and who holds a Canada Research Chair in Nutrigenomics, the science dealing with interaction between nutrition and our genome.
The data suggest that whatever is going on here doesn't have to do with caffeine.
El-Sohemy said coffee is a fairly complex beverage that contains a number of compounds that might have beneficial effects, while others might have adverse effects.
"Whatever is protecting them is not caffeine, so caffeinated beverages other than coffee are not likely to have the same kind of protective effects," he noted.
"Tea might be a little bit different because it also contains other compounds that might be good for you in addition to having caffeine, which might not be good. So it could be the antioxidants, it could be other unique chemicals that are naturally found in coffee that protect."
Lopez-Garcia noted that the study was conducted on a fairly health-conscious population – health professionals – and the findings can't be extrapolated to the larger population. And she noted coffee might be a problem for some people – those with high blood pressure or insomnia, for instance.
El-Sohemy echoed this caution.
"In any study of diet and disease, while we can draw generalized conclusions based on populations, we're really beginning to understand, and it's coming from our knowledge of the human genome, that one size does not fit all," he said.
He noted that a couple of years ago, his research showed that coffee can either increase or decrease the risk of a heart attack, depending on a person's ability to break down caffeine rapidly.
"So while in a population one can see overall a protective effect, for some individuals – and we don't yet know how to identify them – it might actually be harmful."