In an observational study, moderate consumption of unsweetened or sugar-sweetened coffee was associated with lower mortality.

In cohort studies, moderate coffee consumption is linked to lower mortality. Whether this holds for sweetened coffee is unknown. U.K. researchers studied a cohort of ) 170,000 people (mean age 56) who were free of heart disease and cancer and consumed unsweetened, sugar-sweetened, artificially sweetened coffee or no coffee.

Compared with nonconsumers, unsweetened or sweetened coffee consumers had significantly lower mortality after a median of seven years. The association was strongest for 2 to 4 cups daily (hazard ratio, 0.7), with less-strong associations for more and less. Artificially sweetened coffee was not linked to mortality, but a small sample size may have limited detection. The type of coffee (instant, ground, decaf) did not affect these findings.

Multiple factors confound coffee consumption and mortality. Assume a protective causal link. In that case, it may be related to coffee's chlorogenic acids, which have an antioxidant effect and inhibit platelet aggregation. The average amount of sugar added to sweetened coffee was 4 g. (likely less than many Americans add). This study shows that even sweetened coffee is likely safe and may be beneficial.