Americans drink a lot of coffee. Like, a lot. Roughly 80 to 85 percent of Americans drink coffee on a regular basis, according to the American Psychological Association, and the average daily intake is somewhere around 300 milligrams. That's about three (eight-ounce) cups of plain coffee, if you're wondering.
But when it comes to how much coffee is recommended per day, the jury has been back and forth for a while. The 2012 recommendation from the Food and Drug Administration warns adults from exceeding 300 milligrams of coffee a day. As does the recommendation from the International Food Information Council.
Now, a new study published in the journal Food and Chemical Toxicology reviewed 15 years of data to find that consumers can actually safely exceed 300 milligrams a day. Specifically, the average healthy adult can go up to 400 milligrams of caffeine without doing any damage, while pregnant women should stay within 300 milligrams.
Researchers at the International Life Sciences Institute reviewed more than 700 studies published between 2001 and 2015 that looked at the health risks associated with consuming an excessive amount of caffeine from sources ranging from coffee, tea, cola-type beverages, and energy drinks to chocolate, supplements, medicines, energy shots, caffeinated chewing gum, caffeinated sport gel, and caffeinated sport bars. The health risks they looked at were "acute toxicity, cardiovascular toxicity, bone and calcium effects, behavior, and development and reproduction."
"[T]he evidence generally supports that consumption of up to 400 mg caffeine a day in healthy adults is not associated with overt, adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status," the study states.
With levels higher than 400 milligrams, the researchers found links to the likes of depression, anxiety, and hypertension. But that's not to say hitting 500 milligrams a day is a guaranteed travesty. "There's a great deal of inter-individual variability in how people respond to caffeine," Esther Myers, a specialist in systematic research reviews, tells The Atlantic. "That's one of the research gaps. We need to better identify differences and identify people who are more sensitive."
How much is 400 milligrams of caffeine? Depends on what you're drinking. For reference, one can of Coke typically has 34 milligrams of caffeine, a 12-ounce Pike Place roast coffee from Starbucks packs 235 milligrams of caffeine, and a medium coffee from Dunkin' Donuts has 210 milligrams. For plain coffee, four (eight-ounce) cups would sum up to 400 milligrams.
The findings of this study suggest a greater intake of coffee is not harmful, but they're limited to healthy adults. More research is required to see how it would impact those not in a prime state of health or if the health perks associated with low-dose coffee intake are amplified with greater consumption.