Coffee Consumption and Mortality: Reanalyzing the Data

Abstract & Commentary

By Joseph Varon, MD, FACP, FCCP, FCCM. Dr. Varon is Clinical Professor of Medicine and Professor of Acute and Continuing Care at the University of Texas Health Science Center in Houston; and Clinical Professor of Medicine at The University of Texas Medical Branch at Galveston. Dr. Varon reports no financial relationship to this field of study.

Synopsis: Regular ingestion of caffeine, either as coffee, tea or chocolate was followed in 2 large cohorts of men and women for more than two decades. When caffeine was consumed regularly, there was no increase in the overall mortality. Indeed, a modest benefit of caffeine consumption was noted on overall mortality and in particular death related to cardiovascular disorders. This effect was more pronounced in women.

Source: Lopez-Garcia E, et al. Ann Intern Med. 2008; 148:904-914.

This study was aimed at evaluating the effect of caffeine consumption and the risk of death between two large cohorts of health care professionals. These cohorts included the Health Professionals Follow-Up Study (HPFS) and the Nurses Health Study (NHS), which were started in 1986 and 1976 respectively. Participants with pre-existing cardiovascular disease or malignancies were excluded from this study. A total of 41,736 men and 86,214 women were followed until 2004 for the purpose of this study. Participants were sent questionnaires in different years during the study period inquiring as to baseline caffeine consumption and most current ingestion patterns. The investigators estimated that each cup of coffee had 137 mg of caffeine while a cup of tea had 467 mg, a 12-ounce bottle of a soft drink had 46 mg, and a chocolate bar had 7 mg per ounce. Mortality was then followed by either the next of kin, or by accessing the National Death Index. The primary end point of the study was death from any cause and was classified on the basis of the International Classification of Diseases (ICD coding).

The HPFS participants were followed for 18 years and 6888 deaths were identified. Of them, 2049 had cardiovascular disease-related mortality and 2491 had malignancies. The NHS participants were followed for 24 years with 11095 deaths (2368 from cardiovascular illness and 5011 from cancer). After adjusting for confounding variables, such as cigarette smoking, alcohol intake and regular exercise, an inverse relationship between coffee consumption and death was noted. Mortality from all causes was statistically lower in those participants consuming several cups of coffee per week. This effect was more pronounced among women where there was a decrease of 18% in mortality for those drinking 2-3 cups per day and 26% on those consuming 4-5 cups per day. The majority of the risk reduction was related to less cardiovascular illness. Caffeine ingestion was not associated with the risk of dying from cancer.

Commentary

This study showed an inverse association between caffeine consumption and mortality. A number of theories exist as to why caffeine ingestion could cause a decrease in mortality. Many have postulated the beneficial effects of caffeine on inflammation, and endothelial function.1,2 In a previous study, these same investigators had shown an inverse relationship between coffee consumption with surface adhesion molecules and C-reactive protein.3 Others have reported that regular caffeine consumption reduces low-density lipoprotein oxidation, therefore modifying atherosclerotic plaques.4 However, the specific mechanisms explaining the protective effects of caffeine still require studying. For now and until new recommendations arise, a moderate consumption of coffee every day seems to be beneficial.

References

1. Kleemola P, et al. Arch Intern Med. 2000;160:393-400.

2. Andersen LF, et al. Am J Clin Nutr. 2006;83:1039-1046.

3. Lopez-Garcia E, et al. Am J Clin Nutr. 2006;84:888-893.

4. Yukawa GS, et al. Biochemistry. 2004;69:70-74.