Scientists from Spain and the US found that drinking two or three cups of coffee a day did not increase risk of death in either men or women and in fact both caffeinated and decaffeinated coffee were linked with a slightly reduced risk of death from heart disease. However, experts cautioned that this could be the result of something else protecting coffee drinkers that was not studied in the research.
The study, which was supported by grants from theUS National Institutes of Health, is published in the 17 June issue of the Annals of Internal Medicine and is the work of lead author Dr Esther Lopez-Garcia of the Universidad Autónoma de Madrid, Spain, and colleagues from the Harvard School of Public Health, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachussetts, US.
“Coffee consumption has been linked to various beneficial and detrimental health effects, but data on its relation with death were lacking.”
Lopez-Garcia and colleagues found that coffee consumption was not linked with a higher risk of death in middle aged men and women, and suggested that:
“The possibility of a modest benefit of coffee consumption on heart disease, cancer, and other causes of death needs to be further investigated.”
For the study the authors used data from participants who were free of cancer and heart disease on enrollment in two large epidemiological studies, one involving American women and the other involving American men. The data on women came from 84,214 women who took part in the Nurses’ Health Study and the data on men came from 41,736 men who took part in the Health Professionals Follow-up Study.
The participants filled in questionnaires every two to four years that included questions about their coffee consumption (for instance how much and how often), other dietary habits, smoking status, and health.
Lopez-Garcia and colleagues then looked at how different kinds of coffee drinking patterns correlated with frequency of death from any cause, from death due to heart disease, and from death due to cancer.
The results showed that:
- Women who drank 2 to 3 cups of caffeinated coffee a day had a 25 per cent lower risk of death from heart disease over the follow up period (84,214 women from 1980 to 2004), compared with women who did not drink coffee.
- Women who drank 2 to 3 cups of caffeinated coffee a day also had an 18 per cent lower risk of death from causes not related to cancer or heart disease, over the follow up period compared to women who did not drink coffee.
- Men who drank 2 to 3 cups of caffeinated coffee a day showed no higher or lower risk of death during the follow up period, 41,736 men from 1986 to 2004) compared with men who did not drink coffee.
- During the follow up, 2,368 of the women died from heart disease, 5,011 from cancer, and 3,716 from other causes.
- 2,049 of the men died from heart disease, 2,491 from cancer, and 2,348 from other causes.
- Overall, taking into account other risk factors such as body size, smoking, diet, and some specific dieases, people who drank more coffee were less likely to die during the follow up period.
- The main reason for this was the lower risk of heart disease among the coffee drinkers.
- There was no link between coffee drinking and death due to cancer.
- In the main, there appeared to be no difference in the link to death rates between caffeinated and decaffeinated coffee, they both appeared to have the same link with lower death rates compared with people who did not drink any coffee at all.
- However, drinking decaffeinated coffee was linked to a small reduction in deaths from all causes and cardiovascular (CVD) diseases.
The authors concluded that:
“Regular coffee consumption was not associated with an increased mortality rate in either men or women. The possibility of a modest benefit of coffee consumption on all-cause and CVD mortality needs to be further investigated.”
Both the editors of the journal and the authors themselves pointed to a possible limitation of the study: the fact that the data came from self-reports, which could mean some measurement error was present in the results.
Also, the editors wrote that the study was not designed to show a causal link, so we cannot be certain that it was coffee consumption that caused these results, it could something else that links coffee drinkers with lower mortality.
“The Relationship of Coffee Consumption with Mortality.”
Esther Lopez-Garcia, Rob M. van Dam, Tricia Y. Li, Fernando Rodriguez-Artalejo, and Frank B. Hu.
Annals of Internal Medicine 17 June 2008, Volume 148, Issue 12, Pages 904-914.
Sources: American College of Physicians press statement, journal abstract.
Written by: Catharine Paddock, PhD