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Coffee: A Little Really Does Go a Long Way

People who love coffee consider it more than just a drink. It's part ritual, part pick-me-up, part habit.

"It sort of gives me a lift," says long-long-longtime coffee drinker Rich Warwinsky. "And if I manage it well and drink it two or three times a day, half and half, I'm not too crazed."

With this description, it sounds as if Warwinsky is referring to a drug habit. And in fact, he is.

"Caffeine is a drug that can affect our central nervous system and affect some pretty important areas of our lives," says American University caffeine researcher Laura Juliano.

And it's a drug with pros and cons. Caffeine can help put us in a good mood in the morning or help us focus on a task at hand. But it can also make us anxious and interfere with sleep. Juliano is trying to figure out exactly how much she can tolerate. She drinks a little bit of caffeine from coffee first thing in the morning. During a late-morning break at a campus cafe, she ordered decaf.

"Even having it now may have an effect on my being able to fall asleep tonight," she says. "There's research to show that people who have caffeine in the morning can take longer to fall asleep that evening."

Sensitivity to caffeine varies widely from one person to the next. Researchers believe part of the equation is genetic makeup, part is body weight. Also, eating a meal just before consuming caffeine can slow down the stimulant's effect. Smokers can often tolerate more caffeine because nicotine is thought to stimulate the enzymes that break caffeine down.

Juliano says age is another factor.

"People become more sensitve to caffeine as they get older. We require liver enzymes to break down caffeine. And as one ages, there are just changes in our metabolism."

As a general rule of thumb, most caffeine users need a surprisingly small amount of the stimulant to enjoy its pleasant effects. Studies show that 100 milligrams -- just a 6-ounce cup of a typical automatic-drip coffee -- produces a lift.

"People report increased well-being, better mood," Juliano says. "They become more sociable and talkative."

But a higher dose can cause problems.

"Above 200 milligrams -- and certainly by 400 milligrams -- many people report anxious, jittery feelings of uneasiness," Juliano says.

Keeping your daily dose of caffeine under 400 milligrams can be tricky because it's hard to know how much caffeine is in any given cup of coffee or tea.

One study published in the Journal of Analytical Toxicology by researcher Bruce A. Goldberger of the University of Florida College of Medicine shed light on the variability of caffeine content. His research found that 16 ounces of caffeinated coffee from Starbucks had 100 milligrams more of caffeine than the same serving size from Dunkin' Donuts. The study also found that Starbucks' caffeinated breakfast blend, purchased at a Florida store, varied greatly in its caffeine content from day to day. One day, a 16-ounce cup had 259 milligrams of caffeine. Another day, the same size coffee contained 564 milligrams.

Tea offers a much gentler lift. A cup generally contains from 30 to 90 milligrams of caffeine, depending on the variety and how long the bag is steeped. Sodas typically have the least caffeine. A 12-ounce Diet Pepsi, for example, has 36 milligrams.

When people ask Juliano about how to manage their caffeine intake from coffee, she sometimes turns them on to espresso drinks.

Let's say you order a cappuccino, which is made with espresso. "You're actually getting far less caffeine than if you were to get a drip coffee," Juliano says.

"People often think, 'Oh, I had espresso and I really had a jolt.' But in actuality, it could be a better amount [of caffeine] to consume because you're keeping it under 100 milligrams a day, and that's what we recommend, in terms of getting a little boost."

The challenge of our caffeinated society, where eight in 10 adults report consuming caffeine, is that many people fall into dependency without realizing it. What starts as one cappuccino a day can escalate. When this happens, Juliano says, it's not terribly alarming. Compared to classic drugs of dependence, caffeine is considered safe. But there is a downside, which becomes apparent when you skip a day and go into withdrawal.

"The No. 1 symptom you hear people say... is 'Oh, I get this pounding headache,'" Juliano says.

If a caffeine-dependent coffee lover doesn't want a morning pick-me-up on the weekend, cutting back to half a cup is one solution. That little bit of caffeine "may prevent withdrawal," she says.

Then again, you could just break the caffeine habit altogether. If you go cold turkey, research shows that the headaches will last anywhere from a few days to several weeks. Juliano says the other option is to break the caffeine habit over a week or two. That's what she plans to do ... one day soon.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Allison Aubrey is a correspondent for NPR News, where her stories can be heard on Morning Edition and All Things Considered. She's also a contributor to the PBS NewsHour and is one of the hosts of NPR's Life Kit.

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