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Caffeine Jitters

Sales boost in energy drinks and deaths linked to the products make scientists and regulators worry about safe levels of the stimulant

by Lauren K. Wolf
February 4, 2013 | APPEARED IN VOLUME 91, ISSUE 5

Credit: Shutterstock/iStockphoto/C&EN
Caffeine fiends the world over frequently show their love for the stimulant and the buzz it induces.

When Matthew Penbross woke on a morning in August 2007—a day in which he’d be competing in motocross races near Port Macquarie, Australia—he wanted to be prepared. To improve his reaction speed on the start line, the 28-year-old began drinking Red Bull Energy Drinks soon after he rolled out of bed. All told, he would drink seven or eight of the caffeinated beverages within a seven-hour period.

After his second race that day, Penbross wasn’t feeling well. But despite some short-lived chest pains, he kept riding and went on to win a race in the afternoon. Twenty minutes after he crossed the last finish line of the day, though, his heart stopped.

Penbross had no family history of heart disease, and he regularly drank a few Red Bulls per day, news reports later stated. The hospital doctors who treated his collapse and helped him recover went on to suggest that the excessive amount of caffeinated energy drinks he consumed was the likely culprit (Med. J. Aust.2009,190, 41).

Stories like Penbross’ have surfaced with increasing frequency in recent years. According to a report released last month by the U.S. Substance Abuse & Mental Health Services Administration, the annual number of emergency room visits associated with energy drinks increased to 20,000 in 2011, a 36% boost from the previous year. Late last year, the New York Times reported that the U.S. Food & Drug Administration is investigating reports of five deaths linked to Monster Energy drinks and 13 deaths linked to 5-Hour Energy shots.

Credit: Shutterstock/C&EN
Most beverages contain less caffeine than the recommended daily limit, but some are too caffeinated for pregnant women and children. a = Limit proposed by Health Canada. b= Limit proposed by U.K. Food Standards Agency. c = Average value. SOURCES: Consumer Reports, December 2012; Curr. Opin. Pediatr., DOI: 10.1097/mop.0b013e3283506827; J. Am. Med. Assoc., DOI: 10.1001/jama.2012.170614; J. Food Sci., DOI:10.1111/j.1750-3841.2010.01561.x

To download a PDF of this article, visit (C&EN, February 4, 2013, pages 9–12).
Credit: Shutterstock/C&EN
Most beverages contain less caffeine than the recommended daily limit, but some are too caffeinated for pregnant women and children. a = Limit proposed by Health Canada. b= Limit proposed by U.K. Food Standards Agency. c = Average value. SOURCES: Consumer Reports, December 2012; Curr. Opin. Pediatr., DOI: 10.1097/mop.0b013e3283506827; J. Am. Med. Assoc., DOI: 10.1001/jama.2012.170614; J. Food Sci., DOI:10.1111/j.1750-3841.2010.01561.x

To download a PDF of this article, visit (C&EN, February 4, 2013, pages 9–12).

As concerns about the safety of these products have risen, so too have their sales. According to SymphonyIRI Group, a Chicago-based market research firm, the market for caffeinated energy drinks hit $9.8 billion last year.

“People often don’t understand the potential risk of these beverages,” says Bruce A. Goldberger, director of forensic toxicology at the University of Florida’s pathology labs. Caffeine is a stimulant and, when consumed at high enough levels, can have negative effects.

Monster Energy vigorously defends its safety record. In response to the fatality reports FDA is investigating, the company released the following statement: “Neither the science nor the facts support the allegations that have been made. Monster reiterates that its products are and have always been safe.” The firm also says a 16-oz can of its product contains only about half the caffeine found in a 16-oz cup of premium coffee, such as Starbucks.

Caffeine safety has proven hard to measure. Although scientists have established the toxic dose to be somewhere around 10 g, they say that the value can fluctuate depending on how a person processes the stimulant. Caffeine gets cleared from the body at different rates because of genetic variations, gender, and even whether a person is a smoker. For this reason, it’s difficult to set a safe limit of daily consumption on the compound. Physiological differences, as well as differences in the way people consume caffeine, have tied FDA in knots as it has debated how to regulate the substance.

Caffeine has long been prized for its ability to increase a person’s alertness and energy. According to lore, these properties were noted in the 9th century by an Ethiopian goatherd who found his flock frolicking after eating coffee berries from nearby bushes. What is not lore is that caffeine is one of the most frequently ingested pharmacological substances in the world. People proclaim their love of the chemical by displaying its structure on T-shirts, mugs, and jewelry. According to FDA, at least 80% of adults in the U.S. consume caffeine every day.

Scientists know a lot about how the popular stimulant triggers alertness in the body at low doses, says Bertil B. Fredholm, emeritus professor of pharmacology at the Karolinska Institute, in Sweden. Once the compound gets absorbed into the bloodstream, it moves to the liver, where it is metabolized. There, cytochrome P450 enzymes yank different methyl groups off caffeine to transform it into the primary metabolites paraxanthine, theophylline, and theobromine.

Caffeine and its metabolites subsequently bind to proteins called adenosine receptors located throughout the body. When they bind to two of these receptors—named A1 and A2A—the stimulants block the proteins from interacting with their natural partner, the small molecule adenosine. Normally, adenosine’s interaction with its receptors regulates nerve cell activity as well as the release of neurotransmitters such as dopamine. It also promotes sleepiness.

But when caffeine or its metabolites prevent adenosine from doing its job, dopamine and other neurotransmitter levels increase, leading to a surge in nerve activity in the brain and on the heart. This action then causes a jump in heart rate and blood pressure.

Like other indulgences in life, however, too much of a good thing can be bad. “Whereas low-dose caffeine effects are wakefulness, a little bit of arousal, and slight euphoria,” Fredholm says, “high-dose effects are anxiety, irritation, and general mental discomfort—a completely different kettle of fish.” Those negative high-dose effects are especially worrisome, given that researchers still don’t fully understand their origins.

“High-dose caffeine effects are much more complex,” Fredholm explains. “It’s still unknown precisely what the primary mechanism of action is in the brain and elsewhere.”

Credit: Substance Abuse & Mental Health Services Administration
Energy drinks are being increasingly linked with hospital visits in the U.S. NOTE: ER visits for 2012 not yet available. SOURCE: Substance Abuse & Mental Health ­Services Administration
Credit: Substance Abuse & Mental Health Services Administration
Energy drinks are being increasingly linked with hospital visits in the U.S. NOTE: ER visits for 2012 not yet available. SOURCE: Substance Abuse & Mental Health ­Services Administration

The toxic level in humans, about 10 g, is roughly the equivalent of imbibing 75 cups of brewed coffee (in 8-oz mugs) or 120 cans of Red Bull over a few hours.

But that lethal limit can vary widely from person to person, experts say. Caffeine is processed differently in each individual, so setting a precise safety limit is not a straightforward matter.

And standard animal models haven’t been much help. “Mice and rats—the animals we’d normally use to determine lethal doses of substances—metabolize caffeine much more quickly than humans,” says James D. Lane, a medical psychologist at Duke University Medical Center. So it’s hard to compare the health effects of caffeine in rodents and humans, he adds.

For these reasons, scientists have struggled to distinguish benign, low doses of caffeine from troublesome, high doses.

In 2003, a team at Health Canada, a government regulatory agency, reviewed more than 200 studies about caffeine’s effects on human health. On the basis of the survey, the team concluded that 400 mg of caffeine per day (or about three 8-oz cups of brewed coffee) is a safe dose for healthy adults to consume (Food Addit. Contam., DOI: 10.1080/0265203021000007840). At and below this level, the average person does not experience negative mood changes or heart problems, the report stated.

The Health Canada team also recommended a limit of 2.5 mg per kg body weight per day for children. For an average 10-year-old in the U.S., that’s about 75 mg of caffeine, or two 12-oz cans of Coca-Cola.

But these recommended “safe” levels of caffeine are just statistical averages over the population. Some people tolerate caffeine and can ingest large quantities of the compound without ill effects, and others can’t, explains Emma Childs, a behavioral psychopharmacologist at the University of Chicago.

Fifty percent of the caffeine a person takes in gets cleared from the body, on average, in five hours. But studies have shown this rate can vary because of other drug use: Women taking oral contraceptives break down caffeine slower than those not on a contraceptive pill, and people who smoke process the stimulant faster than those who don’t.

Genetics also plays a big role in how a person reacts to caffeine. For example, men metabolize caffeine faster than women.

Scientists have also found that certain DNA sequence variations in the gene coding for CYP1A2, the main cytochrome P450 enzyme that metabolizes caffeine, control how fast or slowly a person breaks down the stimulant. The variations, called single-nucleotide polymorphisms (SNPs), increase the levels of the enzyme present in the liver.

Also influencing how people react to caffeine are SNPs in a gene called ADORA2A, which codes across the body for the adenosine receptor A2A. For instance, Childs and her group showed in 2008 that study participants with a particular SNP in ADORA2A began feeling anxious after consuming only 150 mg of caffeine. Participants without the SNP didn’t experience caffeine-induced anxiety until they had ingested 450 mg of the substance (Neuropsychopharmacology, DOI: 10.1038/npp.2008.17).

Fortunately, Childs says, “people with the ADORA2A polymorphism are pretty cognizant of it.” The gene defect is usually associated with panic disorder, she adds. “So those people know how much they’re allowed to have and when they’ve had too much.”

It’s more difficult, Childs says, to advise slow caffeine metabolizers who have polymorphisms in their CYP1A2 liver enzyme. “Without genetic testing,” she explains, “it’s hard to know whether you need to be careful with intake.”

Because of the variability in caffeine sensitivity among people, FDA has stopped short of recommending a consumption limit for the entire population. The agency goes only so far as to state on its website, “Experts agree that 600 mg (four to seven cups of coffee) of caffeine or more each day is too much.”

The agency has also found it difficult to regulate the caffeine content of food and drink. Caffeine is a psychoactive drug, but it is also a natural ingredient in widely consumed beverages such as coffee and tea.

At one point in the early 1980s, FDA considered prohibiting the addition of synthetic caffeine to soft drinks for safety reasons. But beverage manufacturers claimed the compound was a necessary flavor enhancer for their products.

The agency relented, but it put a limit of 0.02% on the amount of compound allowed to be added to cola-type beverages. That’s a concentration of about 6 mg per oz, a threshold that drinks like Pepsi Max (5.8 mg per oz) bump up against but don’t surpass.

But “beverage” limitations don’t apply to drinks like Monster Energy or 5-Hour Energy. These caffeine-rich products are sold as something different: dietary supplements. The 1994 Dietary Supplement Health & Education Act allows drinks marketed this way to contain ingredients such as vitamins, minerals, herbs, and other substances that supplement a person’s diet. And if one of those substances is caffeine, it is free of FDA’s 0.02% food-additive restriction.

As a result, drinks such as Monster Energy may contain caffeine levels in excess of 6 mg per oz. And because the beverage manufacturers sometimes include caffeine as part of a drink’s proprietary “energy blend,” the amount of the stimulant doesn’t need to be reported on the bottles. These blends include compounds such as glucuronolactone and taurine, although experts agree that caffeine is the active ingredient delivering the power boost.

Cytochrome P450 enzymes in the liver break down caffeine into its primary metabolites by pulling off methyl groups.
Cytochrome P450 enzymes in the liver break down caffeine into its primary metabolites by pulling off methyl groups.

FDA doesn’t have enough evidence to stop the practice, says Daniel Fabricant, director of FDA’s Division of Dietary Supplement Programs. “For FDA to seek a limit on any ingredient in a dietary supplement, we have to demonstrate that there is a significant or reasonable risk of illness or injury under the normal conditions of use or in the labeling,” Fabricant says.

That happened for Canada in 2011 when it announced a limit of 180 mg of caffeine per energy-drink serving. A cap hasn’t been instituted in the U.S., but FDA says it is taking seriously reports of five deaths and about 30 adverse events possibly linked to Monster Energy that have occurred since 2008.

FDA released those records after a Freedom of Information Act request was submitted by Wendy Crossland, the mother of a teenage girl who died in 2011 of a heart arrhythmia. The 14-year-old, Anais Fournier, consumed a 24-oz Monster Energy drink at a mall near Hagerstown, Md. The next day, she drank another 24-oz can and then collapsed.

Each can of Monster contains an estimated 240 to 280 mg of caffeine, a daily dose that is considered safe for adults. Fournier, however, was younger and smaller than the average adult and had a preexisting heart condition.


“Caffeine will increase adrenaline in your body, and it will increase blood pressure,” says Duke’s Lane. For habitual users, “it generally increases the wear and tear on your body.” Healthy adults don’t typically notice these mild effects, but the changes can exacerbate underlying conditions such as heart disorders, particularly at acute doses.

Reports of adverse events connected with 5-Hour Energy shots are also being scrutinized by FDA. Since 2009, the agency has received about 90 filings related to the product, including records of 13 deaths. Unlike energy drinks, which sit on grocery store shelves next to sodas and come in 8- to 24-oz cans, energy shots are sold next to the Tic Tacs and gum at the cash register in 2-oz servings.

Even though 5-Hour Energy bottles do not list caffeine content, in December, Consumer Reports said the shots contain 215 mg of the stimulant. That’s almost seven times the concentration of an average cup of brewed coffee and 19 times the 0.02% FDA limit for beverages.

Living Essentials, the maker of 5-Hour Energy, has responded to the scrutiny by issuing commercials about its product safety and by claiming each shot contains the amount of caffeine in a cup of premium coffee, such as Starbucks.

“But energy shots aren’t cups of coffee. It’s not comparing apples to apples,” says Goldberger, the University of Florida toxicologist. “Your typical cup of coffee comes hot; you wouldn’t usually gulp it down.” On the other hand, he says, “energy shots come in 2-oz containers that can be gulped.”

Lack of data is something else FDA has been grappling with, says supplements director Fabricant. “Looking into adverse event reports is challenging because quite often, you don’t have a lot of background information,” such as the person’s medical history, age, and size or details about exactly what happened. “But we’re always reviewing and rereviewing the reports,” he adds.

The number of drinks it took to cause an adverse event isn’t listed in the records submitted to FDA either. But a survey of calls to an Australian poison information center between 2004 and 2010 suggests that number could be a factor in why people get sick. About 200 calls related to energy drinks came in during the seven-year period, and the average subject consumed five beverages before feeling ill (Med. J. Aust., DOI: 10.5694/mja11.10838).

“It’s generally recognized that caffeine is a mildly addictive stimulant drug,” says Michael F. Jacobson, executive director of the Center for Science in the Public Interest (CSPI), a consumer health advocacy group. Some young adults view it as a legal way of getting high.

The average subject involved in the Australian poison center calls, for instance, was 17 years old. And 30% of the time, the subject used the energy drinks in combination with alcohol or drugs like Ecstasy.

“The Federal Trade Commission probably needs to look into the marketing of these products,” Goldberger contends.

That’s because the amped-up message attached to energy drinks is quite different from the relaxed, good-to-the-last-drop one associates with coffee, he says. One energy drink, called Cocaine, once labeled itself “the legal alternative.”

It’s not just beverages that have been caught up in the caffeine craze: Ballpark favorite Cracker Jack will soon come as Cracker Jack’d—2-oz packages of the familiar candy-coated kernels jammed, in certain flavors, with 70 mg of caffeine from coffee. According to the label, they’re “snacks with impact.”

Cracker Jack’d will also join caffeine-laden candies, waffles, and even pancake syrup. So far, these items are sold mostly on the Internet and haven’t caused problems, says CSPI’s Jacobson, “but if they prove to be popular, you can bet there’s going to be an escalation of small companies selling them in stores. Major marketers might then see the new niche and capture their share of the profits.”

Frito-Lay, the maker of Cracker Jack’d, has responded to concerns about its product line by saying it stands behind the safety of its caffeine-containing kernels. “All marketing for the products will be exclusively aimed at adult consumers, and the package design and appearance are wholly different from Cracker Jack to ensure there is no confusion among consumers,” Frito-Lay says.

CSPI’s Jacobson is not convinced. The trend of pumping products full of caffeine, he argues, deserves attention from FDA before it gets out of hand.

To download a PDF of this article, visit (C&EN, February 4, 2013, pages 9–12).



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Matt Turner (February 4, 2013 4:59 PM)
Why is a 16 oz cup of "Starbucks" coffee much more than 2x as potent than a brewed 8 oz cup??
James Forrest (February 4, 2013 6:27 PM)
Why, but to skew the analysis of course! Starbucks' 16oz drinks come standard with 2oz (2 shots) of espresso. According to the handy chart in the article, 2oz espresso amounts to 80mg, under HALF as much caffeine as in the chart's listing of an 8oz brewed cup of coffee, 133mg. Yet somehow the same 2oz of espresso in a 16oz Starbucks amounts to 330mg magically!? The chart is bogus.
Tom (February 5, 2013 1:02 PM)
James, the chart says "16 oz cup of Starbucks coffee" -- no espresso shots in that.
annalita (February 6, 2013 12:18 PM)
Espresso isn't the same as brewed coffee. If the chart says coffee it likely refers to brewed coffee, not the espresso-based Americano for instance. Given these numbers, an Americano would be a better bet if you're looking to lower caffeine intake (also more tasty imo).
Chris (February 6, 2013 12:37 PM)
"According to the handy chart in the article, 2oz espresso amounts to 80mg, under HALF as much caffeine as in the chart's listing of an 8oz brewed cup of coffee, 133mg."

Check your math, half of 133 is 66.5mg therefore there is more than half the amount of caffeine in an espresso shot than a home brewed cup of coffee. There is 60% the amount of caffeine in an espresso shot with respect to a home brewed cup of coffee. If Starbuck's 16oz drink came with two espresso shots, then that's 160oz from the espresso which leaves 150mg leftover from the coffee itself which would make up the other 12oz of the cup (16 - 2 - 2 = 12). A home brewed cup will have different amounts of caffeine based on the bean, roast and brewing process. The amount listed for the 16oz cup is not farfetched and if you think it is, just go ahead and have one. It will keep you up, that is for sure.
Rover (February 6, 2013 4:01 PM)
I'm no nath guy but if 160mg of caffeine comes from 2 booster espresso shots in the Starbucks coffee, doesn't it leave a remaining 170mg of caffeine from the remaining 12oz of leftover coffee(330-160mg) and (16-(2x2)=12oz coffee left)?

If 8oz of brewed coffee gives you 93mg of caffeeine @ 11.625mg caffeeine/oz of coffee, then 12oz gives you 139.5mg of caffeine.
Total caffeine in Starbucks should be 160+139.5= 299.5
Remaining 30.5mg of caffeine? Magic I guess.....
Like he said....chart is bogus.

Also, Starbucks coffee beans are not stronger than regular coffee beans because they do not have a magic strain of Arabica coffee beans that is stronger than regular coffee.
asdf (June 10, 2013 1:43 PM)
8oz of brewed coffee gives 133mg, not 93mg (93mg is from instant coffee). Also, the 330mg of caffeine in Starbucks 16 oz coffee appears to come right from their menu:

Don't try to calculate stuff like this with assumptions. Get the facts straight.
Steven C (February 7, 2013 12:40 PM)
Chris, check with your Barista! The espresso shots are not added to brewed coffee. Normally milk (Grande Latte etc.), syrups or chocolate, or even just water (Grande Americano).

Grande size (16oz) has 2 espresso shots unless you request more. The cited sources suggest 40 to 64mg caffeine per 1oz shot, therefore 80-128mg caffeine. Still somewhat short of the dubious 330mg claim.
Torrey (February 6, 2013 2:55 PM)
The 330mg of caffeine in Starbucks 16 oz coffee appears to come right from their menu:

Grande 16oz - Nutrition Facts Per Serving (16 fl oz) - Caffeine 330mg
Jungle (February 14, 2013 9:18 PM)
confirmed! it is funny to see so many argue a point without doing any research.
Steven C (February 7, 2013 12:30 PM)
One of the chart's own cited sources, doi:10.1001/jama.2012.170614 gives an 'average value' of 85mg in 8oz brewed coffee, which would place it below most of the energy drinks. But the chart shows it as 133mg. The Starbucks figure also seems false by a factor of 2x or 3x. But is what has been repeated already in UK media. Lawsuit anyone?
Shawn (February 7, 2013 5:35 PM)
Also bogus is where a bromine might appear from shedding a methyl group. In the metabolite breakdown, that path makes no sense. Even if true, what is the import?
Ryan (February 10, 2013 2:04 PM)
Are you talking about the 'bromine' in theobromine? There's not actually any bromine in theobromine, and there isn't any sulfur either.
John Milligan (March 11, 2013 11:29 PM)
The theobromine is from "food of the gods" because it was first found in chocolate. It was only later discovered to be a metabolite of caffeine.
Jenna (March 19, 2013 3:49 PM)
Starbucks does sell regular coffee, not just espresso drinks. Do you not know that?
Rusty (February 4, 2013 6:31 PM)
Because Starbucks probably uses stronger beans and its twice the amount.
Sample (February 6, 2013 9:07 PM)
They just use more coffee per oz of water than other coffee places, this gives starbucks brewed coffee that bold kick.
Nope (February 4, 2013 9:49 PM)
I couldn't find a source, but one blog claimed Starbucks "double brews" by using more coffee grounds per batch resulting in stronger coffee.
Mike McCluskey (February 5, 2013 11:19 AM)
because 8x2=16.
Sam (February 6, 2013 11:16 AM)
Starbucks coffee has a lot more caffeine in it than regular coffee. The 330mg is accurate.
Tom S. (February 6, 2013 2:15 PM)
According to Starbucks nutritional information 330mg is correct
Vic Torino (February 7, 2013 5:54 PM)
Isn't is obvious?
Edie (February 8, 2013 11:05 AM)
Because there is a variance in caffeine content of different coffees and how they are made. See
andy (February 4, 2013 5:39 PM)
We should totally concentrate on keeping pot illegal. /facepalm
Can't Stop/ Won't Stop (February 4, 2013 6:04 PM)
Nos has 260 mg of caffeine per can. I'm pretty sure it gave me appendicitis, but it's worth is because it tastes good and feels like I shot up some crystal meth (I would imagine)
chris (February 4, 2013 6:35 PM)
I really don't see caffeine disappearing or being scaled down at all, ever. They are labelled as dietary supplements (the energy drinks) and should be treated as such; if you can't stomach 6 meals within an hour, why should you consider trying to stomach 6 cans of it within an hour? That's not exactly apples to apples and i know it varies blah blah blah. personally i think it's a load of BS because i've combined 2 monster nitrous anti gravities with 3 bottles of extra strength 5 hour energy, 2 zipfizz oranges, and 4 oz of 5150. 5150 alone has 500mg of caffeine per oz. hey, still breathing, and breathing well for that matter.
grahams (February 4, 2013 8:32 PM)
@Matt Turner:
Coffee beans that are less roasted (cheaper quality usually) have more caffeine in them.
fading (February 4, 2013 10:37 PM)
I dont usually have a caffeine sensitivity but on one occasion i had Starbucks brand brewed coffee at home and had two relatively big mugs full of it over the period of like 2 hours and then i drank a Bawls Energy drink (I had never had that brand, but have had others like monster, red bull, rockstar, 2 hr energy, etc) and somehow either just the energy drink or the combination of the coffee and the energy drink caused me to start like full body shake and unable to stop! Scared me so much i did go to the ER. They didnt do crap, and basically kept asking me if i had taken any drugs.... First thing they did was run a urine test. They did do an EKG...and then put me in a bed (not hooked up to any monitors, no IV etc) and didnt even check up on me, it eventually went away on its own and i asked to leave.
Steve (February 4, 2013 11:28 PM)
I'm kinda libertarian on this type of thing BUT there is something odd going on with these energy drinks, beyond just telling people how much caffeine there is on the label. I used to drink 1 Monster every day for months, no problem, felt fine... then one day out of nowhere it caused a sudden huge rash on my torso and tingly tightness in my chest... I know it was the energy drink because any time since then, if I even have one, this happens, so I have stopped completely. At least from my personal experience, there seems to be a threshold where things appear fine, but in the background something builds up, causing a significant reaction at some point, even with moderate use. This should be looked into further.
landale (February 5, 2013 6:47 PM)
Steve, it sounds like you're actually having a mild allergic reaction. You can become allergic to anything at any time, so it makes sense that you consumed these beverages for months until it happened.

My husband had the same problem with the painkiller Aleve. Fine for years, then one day he took it and came out in a huge itchy rash on various spots of his body. We narrowed it down to that and now he doesn't take it at all and hey - no rash.

This is why I stick to a good cup of java for my energy boost - less ingredients to potentially cause a reaction. I used to drink energy drinks every day and then stopped when it became clear they were affecting my sleep. Now I have a large cup of coffee in the morning and I'm good for the rest of the day. Occasionally I'll drink a caffeinated soda but I never feel anything from those.
realsit (February 6, 2013 12:43 PM)
Agree with the allergy thing. Happened to me with chocolate a while back (it sucks!) THe important thing to keep in mind is that while we're focusing on caffine which has a relatively good saftey record, these suckers have ALL SORTS of other stuff in them, some well understood, some not so much. I'm still drinking blue monster though...
Anna O. (February 4, 2013 11:52 PM)
Matt, several factors affect the caffeine concentration in a cup of coffee. Some strains of coffee plant produce more caffeine than others, and the amount within a strain can vary depending on growth conditions. Then, the roasting process burns off some caffeine, so darker roasts actually contain less caffeine than lighter roasts. A rougher grind of the beans leads to more caffeine leaving the bean and entering the brew liquid. Finally, the length of the brew time is important- the longer you brew, the more caffeine leaves the beans. The values quoted here for an 8 oz cup of brewed coffee vs 16 oz at Starbucks are not unreasonably different, although it is true that Starbucks coffee is typically stronger than average.
J1shalack (February 5, 2013 9:44 AM)
We should restrict caffeine to people over 21 and licensed to drink it. They should not be able to buy multi-packs and not be permitted to carry them. There should be a national registry of who buys and drinks caffeinated beverages. Our governments should micro-manage our lives to the tiniest point and remove all possible risks. After all, we are obviously too stupid to think for ourselves...
landale (February 5, 2013 6:59 PM)
It's all about being responsible and listening to your body. It makes sense that nobody should drink 8 Red Bulls, but people are so impatient that they drink a caffeinated beverage and expect the effects to kick in right away. It's like taking 8 painkillers because 2 didn't work right away (I've known people to do this). These things take time to metabolize in the body.

Also another worrying trend is people using caffeine as a substitute for sleep. There's no shortcut that gets us around a good 8 hours a night, but I work night shift with people who think it's OK to sleep as little as 2-3 hours. Couple that with energy shots and you have a recipe for disaster. Think about all the strain you're putting on your heart when you push your exhausted body to go beyond its limits. Here in America we seem to resent sleep as a waste of time, which results in accidents and strain on the body and mind. Better sleep discipline needs to be taught and that would reduce the need for energy shots in the first place. Instead we've become a 24/7 society where we never seem able to tell anybody or anything to just wait. My coworkers are shocked I turn off my cellphone when I sleep. "But what if somebody calls?" That's what voicemail is for, in my opinion. The thousands of texts you are receiving from people who demand you respond is destroying your ability to shut down and rest, leading to a more dangerous, more cranky workplace.
snertking (February 6, 2013 1:18 PM)
oooh... a whopping 21 admissions to ER rooms in 2011... it's a god damn epidemic.
SRSLY, i bet if you could mine the data fully, you'd find many more innocuous things have much higher rates of being associated with ER room visits. I'd bet dollars to donuts for instance rubber bands account for way more ER visits each year than a measly 21... perhaps we need to regulate them too...
Jason (February 6, 2013 1:46 PM)
That is 21,000 in 2011
aqualad (February 6, 2013 3:29 PM)
thats 21 thousand. Not 21. and in responding to J1shalack, yes, it appears that some people are too stupid to thing (or analyze) things for themselves. especially children and uninformed/uneducated adults.
Bob (February 6, 2013 3:31 PM)
Sporting activities. The number of ER visits associated with sports is huge. Should probably just flat out ban sports of any kind. Not to mention cars, motorbikes, hammers, screwdrivers, power tools, stairs, water.....
Wes (February 6, 2013 3:44 PM)
That chart is in thousands. 21,000 ER visits in 2011.
generalpf (February 6, 2013 3:54 PM)
That's in thousands, dude.
Pump_Dragon (February 6, 2013 5:34 PM)
That is in thousands genius
chucktesya (February 6, 2013 6:02 PM)
21000 dumbass, not 21. Graph is in thousands.
christine voor (February 6, 2013 5:08 PM)
Too much caffeine is not good , period ! Too much of anything is bad. Too much caffeine gives me the shakes and causes my heart to race, listen to your body its trying to tell you something,
laurenkwolf (February 6, 2013 6:25 PM)
Um, @snertking, just to clarify, you've read the graph incorrectly. It's in units of thousands. So, that's more than 20,000 ER visits. Not 21.
Aaron (February 7, 2013 10:20 AM)
If only people could read, eh?
Nobody (February 7, 2013 9:18 AM)
It's fascinating how biased people become when something they hold dear is revealed to be more dangerous than they expected.
Steven C (February 7, 2013 12:11 PM)
A Starbucks Grande (16oz) what? I see no mention of Starbucks or Grande in the cited sources...

Starbucks Grande-size espresso-based hot drinks are made with 2 espresso shots unless you requested extra, so presumably 2x64mg = only 128mg.

I doubt a 16oz drip-brewed coffee could be much more than 2x the cited figure for 8oz brewed coffee, 2x85mg = 130mg

You could combine these to make the cocktail known as 'red eye' (definitely not on the menu), but even that could be estimated as 185mg (filter coffee with single shot) from the figures cited in these journals.

To get 330mg caffeine from a single drink at Starbucks you may need to order a Quad Venti (20oz) Mocha (I estimate 4x85mg = 340mg, plus whatever caffeine content the chocolate has).
Michael Gross (February 7, 2013 3:32 PM)
As I see it, it's not the caffeine that's the problem but the abuse by the user.
laurenkwolf (February 11, 2013 12:09 PM)
Hi all, I see a lot of readers stumped by the 330 mg value listed for Starbucks coffee. That's a grande brewed coffee. Here's a good link for you:
You see the 330 mg listed clearly.
Matt (February 11, 2013 7:48 PM)
FYI-Starbucks coffee isn't a special anything. They use Breakfast Blend as their basic coffee measure which is a medium roast-They use 8oz of ground coffee per pot. That's how they get their caffeine content and they admit it varies widely on the very same site you all reference. Dunkin Donuts coffee by comparison is 203 mg of caffeine in a 16 oz cup (they say 178 mg per 14 oz or 12.7142 mg per oz). This amount isn't a surprise because Dunkin Donuts uses 6oz of ground coffee per pot. Thus the difference in the caffeine measure.
melody (February 15, 2013 2:48 PM)
I'm enjoying these comments! One commenter above talked about roast type, grind, and time brewing as having an effect on caffeine in coffee. I've noticed since I switched from standard Mr. Coffee drip to a French press I can drink 2 or 3 cups of coffee without those anxious side effects. Also a French press makes me feel classy and smug- another benefit. Before I used to get unpleasant after cup #2. This is not a scientific data point, though.
Dennis Lynn (February 16, 2013 10:16 PM)
Why not create a new energy drink that is mixed with grapefruit juice. So the P450 system can be inhibited by the gf-juice and increase the effects of the caffeine!

GFE-Juice = grape fruit energy juice. Same amount of caffeine, twice the toxicity!
Rajiv (May 13, 2013 7:25 AM)
I'm glad that people are taking proper notice, although caffeine in moderation is not necessarily bad for you it is important to regulate ourselves. Far too many products have caffeine in them, this all mounts up and we then find ourselves in a problem. I'm working on a coffee alternative that is naturally caffeine free and if any of you are interested in free samples head over to

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