Both coffee and tea can also serve as healthier substitutes for other drinks, too. “If you drink coffee and tea, you are not drinking soda or soft drinks—that clearly is bad for you if they contain sugar,” Dr. Buettner says.
There are some big caveats here, though.
For starters, the study didn’t prove that drinking several cups a day of coffee and tea will help you live longer—it just found an association. Also, the researchers didn’t drill down into what people were having in their coffee or tea, or even the types they had. So, people who regularly enjoyed black coffee and unsweetened tea were also lumped in with those who had specialty coffee drinks and sweet tea.
Keatley also points out that this drink combination provides a lot of caffeine and is on the higher end of what is considered healthy. (The Food and Drug Administration suggests having no more than 400 milligrams of caffeine a day.) “Although there are clear benefits to drinking coffee and tea, it’s important to remember that caffeine has a safety threshold,” Moskovitz says.
Caffeine can also come with side effects, especially when you have it in higher doses, Keatley says. “Caffeine blocks adenosine, the chemical that signals the brain to rest, which increases cortisol and keeps the nervous system in a ‘switched on’ state longer than most people realize,” he says. After a while, this can mess with deep sleep, slow physical recovery, and create dependence on caffeine to function, Keatley points out.
Too much caffeine can also irritate your stomach or worsen reflux, which can damage your esophageal lining and even raise your risk of esophageal cancer, Keatley says.
Finally, Keatley flags something else to consider. “Every single researcher is from the People’s Republic of China, who produce about 40% of the world’s tea,” he says. “Aside from being the largest producer of tea, China is the largest exporter and cultural promoter of tea, which means there is strong economic incentive for positive findings and for framing tea as a national health asset.”
So, what should you take away from this?
If you enjoy having coffee and tea in your day, you’re fine to keep doing just that—provided you stay under 400 milligrams a day (about 32 ounces of coffee) and don’t experience any side effects. But it’s important to make sure you’re getting in plenty of fluids to keep you well-hydrated.
