Drinking Coffee Has Benefits, But It Should Come With These Disclaimers

Findings from one-off studies aren’t the same as doctors’ orders. Even the meta-analysis that looked at 28 studies and found people could drink up to six cups of joe per day without increasing their risk of type 2 diabetes wasn’t meant to be prescriptive, says Jessica Yeh, Ph.D., an epidemiology researcher at Johns Hopkins School of Medicine. (Yeh worked on one of the studies included in the meta-analysis.Coffee and sweetened beverage consumption and the risk of type 2 diabetes mellitus: the atherosclerosis risk in communities study. Paynter NP, Yeh HC, Voutilainen S. American journal of epidemiology, 2006, Sep.;164(11):0002-9262.)

“The implication of this study is that if you’re drinking a lot of coffee, maybe it’s not such a bad thing,” she says. “If you’re not already drinking coffee, there’s no reason for you to start to prevent type 2 diabetes.” Not to mention, many of the studies included in the meta-analysis are based on self-reported coffee drinking, which isn’t the most reliable measurement, Yeh says.

We take study findings to be gospel, but they often look at a very specific subset of people. The one that found drinking four cups of coffee before working out increases stamina, for example, was done on eight super-fit male cyclists (a.k.a. not an accurate representation of the everyday Americans).

Similarly, the study that linked drinking coffee with lower risk of depression and the one that found a decreased incidence of skin cancer only included female participants.Increased caffeine intake is associated with reduced risk of basal cell carcinoma of the skin. Song F, Qureshi AA, Han J. Cancer research, 2012, Sep.;72(13):1538-7445.

And we know caffeine can affect men and women differently. “For women especially, caffeine could interrupt your sleep cycle, increase your blood pressure, and lead to anxiety,” says Taz Bhatia, M.D., a women’s health and integrative medicine expert.

Some of coffee’s key benefits (like improved heart heath and alertness) are thanks to antioxidants. But coffee doesn’t have a magical amount of antioxidants you can’t get elsewhere, says Mark Carter, M.D. “You can get plenty of antioxidants from eating colorful veggies and a varied diet in general,” he says.

This is especially important to consider since coffee comes with obvious drawbacks. “Caffeine is a stimulant, and this may affect sleep/wake cycles and other physiological measures, such as blood pressure and heart rate in the long term,” says Dan Park, M.D., an emergency medicine physician at the Medical University of South Carolina. None of the doctors we spoke with suggested drinking more coffee to just to reap health benefits.

Most of the studies cited in the video call for drinking more than four cups per day (and some even suggest downing them in under an hour!). “When you drink that much coffee, you’re really ramping up your nervous system,” Carter says. “Eventually, there will be some sort of burnout.”