For many people, the morning can’t begin without a cup of coffee. It’s the boost they need to wake up and get ready to face the day. And one cup is often not enough. But what are the risks – and benefits – associated with coffee consumption?
According to an extensive new study from the University of California, San Francisco (UCSF), it appears there are both positive and negative consequences to drinking coffee – though the negative ones don't seem harmful to health. One-hundred healthy men and women in San Francisco participated in this real-world study. Equipped with Fitbits, electrocardiogram devices, and continuous glucose monitors, they recorded their coffee consumption. Participants drank as much coffee as they wanted for two days, then abstained for two days, repeating this cycle over a two-week period.
The study's major takeaways include the fact that people take an average of 1,000 additional steps on days when they drink coffee, perhaps because they feel more energized or motivated. That increase in physical activity translates to a 6% to 15% decrease in mortality. However, coffee consumption was clearly linked to getting less sleep – 6.6 hours with coffee compared to 7.2 hours without it. The extent of the effect depends on how quickly you metabolize caffeine and how many cups you drink (not surprisingly, more cups equals less sleep).
The study also found that drinking coffee was linked to premature ventricular contractions. These extra or irregular heartbeats are common and are thought to be benign – though this may not apply to people with heart disease (or a high risk based on family history). Coffee consumption did not appear to increase the incidence of premature atrial contractions.
Walk more, sleep less:
- Two-thirds of American adults drink coffee on a daily basis.
- Consuming four to five cups of brewed coffee in a day is considered safe for a healthy adult. This amount would contain approximately 400 milligrams of caffeine.
- Dr. Gregory M. Marcus, one of the study's authors and a professor of medicine at UCSF, endorses the idea that coffee can cause different effects in different people. “The reality is that coffee is not all good or all bad." He also said that, "In general, this study suggests that coffee consumption is almost certainly generally safe."