By TAP Integrative

Coffee is one of the most popular drinks worldwide, and there’s no shortage of research looking into its effects on health. The research is often conflicting, though; some studies suggest coffee intake protects health, while others find the opposite.

In an attempt to clarify coffee’s health effects, researchers from the Harvard School of Public Health analyzed data from three very large cohort studies: the Nurses’ Health Study (74,890 women), the Nurses’ Health Study 2 (93,054 women), and the Health Professionals Follow-up Study (40,557 men). The researchers sought to answer four questions about how coffee consumption influences mortality:

  1. Is there a nonlinear relationship between coffee consumption and mortality? In other words, does moderate coffee consumption offer more protection than heavy consumption?
  2. If a nonlinear association exists, could it be because of the confounder of smoking?
  3. What are the associations between coffee consumption and individual causes of mortality—specifically cardiovascular disease and cancer?
  4. Do caffeinated and decaffeinated coffee have the same effects?

After analyzing more than 4 million person-years of follow-up, the researchers determined that consumption of coffee—both caffeinated and decaffeinated—was nonlinearly associated with mortality. Consuming one to five cups a day was associated with a lower risk of mortality than non-consumption, but more than five cups a day was not associated with risk of mortality. However, when looking at people who had never smoked, the association became linear and inverse. That suggests the nonlinear association in the general population was due to confounding by smoking.

The size of this study lends its findings strength, but it is limited by the fact that it relied on food frequency questionnaires, which are prone to reporting errors. It also included primarily white professionals, making it impossible to extrapolate results to other groups. However, in the context of previous studies that have found an inverse relationship between coffee consumption and mortality, the results from this study suggest coffee consumption can be part of a healthy lifestyle.


Ding M, Satija A, Bhupathiraju SN, et al. Association of coffee consumption with total and cause-specific mortality in 3 large prospective cohorts. Circulation. 2015;132(24):2305-2315.


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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.