Wait, So How Much Caffeine Is Okay?

A caffeine researcher explains how much coffee and soda is too much.

I started drinking coffee when I was in middle school. Since then, I've grown into what I think of as an "avidly caffeinated person." My morning cup of coffee prevents a headache, cups two and three get me through my morning writing, and cup four is a nice little cap to my afternoon. Coffee is a big part of my day, and I love it. But lately, I've been wondering how much daily caffeine is the "right" amount.

As you've likely heard by now, Panera has faced several lawsuits in recent months, with its "Charged Lemonade" at the center of each. This lemonade contains almost as much caffeine per serving as is recommended in an entire day, and the lawsuits allege that multiple people have died as a result of consuming it. In turn, Panera has changed its approach to the lemonade, changing its labels and keeping it behind the counter, away from its self-serve drinks. (As of now, however, the restaurant is still selling it.)

Since the emergence of the Panera lawsuits, I've found myself wondering about my own caffeine consumption. Is my normal routine too much? If I have a work deadline to meet, would it be dangerous to add one more cup in the afternoon?

Your caffeine consumption is probably fine

To get the answers to these questions, I connected with Jennifer Temple, Director of the Nutrition and Health Research Laboratory at University at Buffalo. Temple's research includes, among other things, the effect of caffeine on the body.

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"Whatever you're doing is probably fine," said Temple after I had explained my conundrum. She went on to explain that under normal circumstances, which for most people means slow consumption of about 100 mg of caffeine per serving, our bodies have a pretty solid ability to cut us off when we're consuming caffeine. The stimulant is metabolized in about 10 minutes, and when we've had too much, our bodies have numerous ways of letting us know.

"It varies from individual to individual and can be hard for people to put into words," said Temple. "It's a combination of jittery and nauseous. You start to feel shaky, your stomach doesn't feel quite right. Some people report that their heart starts racing, or they might feel dizzy, have an urgency to urinate, they might report feeling kind of anxious. It's a combination of cardiovascular symptoms that are tied to more emotional response."

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Just about everything Temple said resonated with me. I know very well the feeling of making that extra cup of coffee and then, a few sips in, as it starts to metabolize, realizing that it's not making me feel great. At that point I usually just stop drinking it, which is apparently true for most people.

"Surveys suggest that regular caffeine consumers basically titrate the amount they drink based on how it makes them feel," said Temple. "You know when you've had too much, and you stop drinking."

Some people tolerate caffeine better than others

Temple said that studies on the upper limits of caffeine tolerance are limited, because it wouldn't be ethical to toy with giving people too much caffeine, as caffeine overdose can cause cardiac arrest and death.

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For the most part, though, healthy adults are able to consume around 400 mg of caffeine daily, roughly the equivalent of four mugs of home-brewed coffee. Still, Temple said, there are some people who drink more than on a daily basis and have no ill effects.

Why drinks like Panera’s Charged Lemonade can be dangerous

In the case of a highly caffeinated lemonade, like the one involved in the Panera lawsuits, there are a few things that could contribute to trouble.

The first is that Panera's Charged Lemonade contains more caffeine than even some energy drinks do. Moreover, lemonade is a drink that practically no one associates with caffeine. Lemonade is so dissociated from caffeine, in fact, that Temple has used it in studies where she needs a placebo to a caffeine drinker and needs the person drinking it to absolutely believe they are not drinking caffeine.

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"We use lemonade when we're trying to remove expectancy," she said. "We use it as a neutral beverage [in which] no one would ever expect caffeine."

That means that without proper labeling and warnings, it's plausible that customers could consume caffeinated lemonade without realizing it's caffeinated, or could give it to their child without realizing it has caffeine.

Also, for the most part, people sip coffee slowly, in part because we know that if we down too much caffeine all at once, we might feel sick. Coffee is a delight, but it isn't necessarily thirst-quenching. Lemonade, on the other hand, is famously refreshing, and I definitely drink lemonade in a different manner than I do coffee—often, I gulp it down. If I were to unwittingly drink a bunch of caffeinated lemonade, I might already have consumed too much by the time I figured it out.

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"One of the dangers is that because lemonade can be so quickly consumed, you might feel those signals that are telling you to stop drinking caffeine, but you've already had too much," said Temple.

Caffeine overdose is very dangerous, but also very rare

Temple said that caffeine overdose is exceedingly rare, largely because of the warnings our bodies give us when we're consuming caffeine under normal conditions (relatively slowly and in normal amounts). But when it does happen, it affects the heart and can lead to cardiac arrest and death. Which is why it's especially important that when products do contain caffeine, particularly in high doses, it's made very, very clear to consumers via labeling.

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Unfortunately, Temple says there's not a drug to reverse the effects of too much caffeine, the way Naloxone can reverse the effects of an opioid overdose. As a result, the best tool we have in our toolbox is to be mindful consumers. This means drinking caffeine in doses we know we're generally able to handle, listening to our body when it tells us we've had enough, and being aware and careful when we're consuming things we don't typically associate with caffeine, like lemonade and noodles.

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