Whether you drink it hot or cold, coffee is one of the most consumed drinks in the world. Americans alone drink 400 million cups of caffeinated joe a day.
Caffeine, a key ingredient in coffee, is the world’s "most widely used mood-altering drug,” says Dr. Roland Griffiths, a professor in the departments of psychiatry, behavioral science and neuroscience at the Johns Hopkins School of Medicine. “In our country, coffee and soft drinks are the primarily vehicle. In China and the UK, tea is the predominant source of caffeine. In Nigeria, you might chewing cola nut. These are all vehicles for caffeine delivery.”
And caffeine does deliver. According to Griffith, its psychoactive properties start at about 20 milligrams. In order words, just a few sips of coffee.
As part of a two-day series "Caffeinated Nation" TODAY tested some of the major coffee brands to determine which had the most caffeine content. Turns out there's a big range -- at the top is Starbucks medium roast with 250 milligrams in a 12 fl. oz size. The other end of the spectrum is Seattle's Best, with about half as much caffeine at 125 mg per 12 fl. oz. In the middle is Dunkin Donuts and McDonald's at about 165 mg (the Dunkin Donuts small size is 10 oz.)
Caffeine is safe for most people, as long as you keep your daily caffeine intake at under 500 milligrams -- or about two cups of Starbucks coffee -- nutritionist Monica Reinagel, author of "Nutrition Diva's Secrets for a Healthy Diet," told TODAY anchor Savannah Guthrie Thursday.
However, some people are super-sensitive to caffeine's effects.
"People’s sensitivity is different with a lot of substances. Some people need more than one aspirin to get a headache to go away," says TODAY diet and nutrition editor Madelyn Fernstrom. "It’s the amount of caffeine you have and the hard wiring of your brain."
If you are sensitive to caffeine, Fernstrom suggests moderating your intake. “There are really no clear life-threatening health risks associated with caffeine use – however, that doesn’t mean it’s completely benign,” says Griffiths. “There are certain medical conditions that are made worse by caffeine, for which physicians would recommend cutting back: anxiety disorders, sleep disorders, some kinds of stomach disorders, some kinds of heart disorders and pregnancy.”
If you’re a habitual coffee or soda drinker and want to cut back, you should do it gradually.
Fernstrom suggests people cut back to split shots -- half caffeine / half decaf -- or alternate decaffeinated products with the real thing.
“Cutting back gradually over a week’s period is the solution,” she says.
Headaches are a common side effect for those who quit cold turkey. But Griffiths says if you're especially sensitive to caffeine, you might experience more.
“There are wide differences in the expression of caffeine withdrawal,” he says. “You can find two people who are habitual consumers – one of whom will report no apparent effects and the other who will be totally debilitated, experiencing excruciating headaches, muscle pain, lethargy or nausea."
While caffeine is a diuretic -- that means it makes you pee a lot -- coffee contains a lot of water, so it's actually hydrating, Reinagel said Thursday.
Along with providing us with mental focus and alertness, the fact that it comes from a plant means it contains antioxidants.
“Studies continue to show that antioxidants are shown to be health promoting for digestive health, brain health and kidney health,” says Fernstrom.
Most of us, however, simply love the way it tastes – and makes us feel.
“I have to have at least two cups before I can even process information,” says Charlotte Johnson Melton, a 35-year-old high school registrar from Danville, Virginia, who started drinking coffee when she was a little girl. “I even have at least two cups in the evenings, usually decaf. I kill K-Cups. My kitchen is where they come to die.”
Since coffee is a favorite way we consume caffeine in the US, we want to hear how you feel about the bean.
Ok, so you like coffee. But how much?
If you want to share your thoughts about caffeine, #caffeinatednation