That's about three cups per coffee drinker in the United States, where 83 percent of adults can't imagine life without their favorite cup of java.
Add to that tea, caffeinated soft drinks and those infamous energy drinks, and you won't be surprised to read that 90 percent of us consume caffeine in some form or another each day. Is this a bad thing? Not entirely.
Recent research has shown that coffee, in particular, may help prevent diseases like stroke and certain cancers, lower our risk of Parkinson's and dementia, and boost our concentration and memory. Partly that's because coffee beans are seeds, the National Institutes of Health (NIH) reminds us, and like all seeds, they're loaded with protective compounds.
"Coffee is an amazingly potent collection of biologically active compounds," Walter Willett, M.D., of the Harvard School of Public Health, told the National Institutes of Health's newsletter.
Caffeine, a mild stimulant, also provides benefits: It's been linked to lower risks of Alzheimer's disease, for example. But when it comes to caffeine, there really can be too much of a good thing. Those who study caffeine's lesser-known effects point to studies that indicate it can be worrisome for people with high blood pressure, diabetes and osteoporosis. Plus, caffeine can interact poorly with some common medications, and it can worsen insomnia, anxiety and heartburn.
It would make things easier if the caffeine content were listed on food labels so you would know if you've exceeded the 300 mg level that most health experts say is a safe, moderate amount for the day — about the amount in three 8-ounce cups of coffee, depending on how strong you brew it — but so far that's not happening.
So before you turn on that coffeemaker or grab a grande cup from your favorite cafe, here are some things to keep in mind.
First, the bad news about caffeine (and coffee)
Remember: Caffeine is a drug, says Steven Meredith, a researcher in behavioral pharmacology at the Johns Hopkins School of Medicine.
While low to moderate doses are generally safe, caffeine is addictive and users can become dependent on it and find it difficult to quit or even cut back, he says. (Caffeine dependence was even named as a new mental disorder this year.) Anyone who's ever quit cold turkey knows it can trigger pounding headaches, mental fuzziness and fatigue for a couple of days until the body adjusts.
Next page: Coffee and a touchy tummy. »