Caffeine and Energy Drinks: Consumption and Safety

November 3, 2011

There was a period when European civilization existed without any access to caffeine-no coffee, no tea, and no cocoa. This era was known as the Dark Ages.

Caffeine is the most widely consumed neuroactive substance in the world, surpassing alcohol and nicotine. Annual coffee bean production is on the order of seven million tons per year. Add tea and ready-to-drink beverages (carbonated and not), and most of the world has a caffeine habit. But in recent years, caffeine has broken away from its traditional beverage sources and widened its scope to new venues: “energy” drinks, sports performance enhancers, and alcohol-containing beverages. This expansion, with concomitant aggressive marketing to adolescents and young adults, has engendered a negative expert opinion and regulatory backlash.

How does caffeine work? For one, caffeine occupies receptors for adenosine-a naturally occurring fatigue-signaler in the brain (see figure on page 40). Adenosine is released into the blood after prolonged lack of sleep and also in the evening as available light dims. There is an important difference between this signal of fatigue and actual fatigue. Using caffeine does not eliminate the need for sleep; it just puts the signal for sleep to sleep for a while. People who wake up after an insufficient amount of night’s sleep still have elevated adenosine; hence the miraculous impact of a morning cup of coffee.

The surprising reality is that 10 years of explosive growth of caffeinated energy drinks has not resulted in a net increase in caffeine consumption. According to National Health and Nutrition Examination Survey (NHANES) data posted by the USDA, little, if any, change in per capita caffeine consumption has occurred since the 2001-02 survey.(1) Table 1 shows the 2007-08 survey results by sex and age.

Over the near-decade period covered by the NHANES surveys, coffee consumption declined slightly, finishing at about 24 gal/year, as did carbonated soft drinks, finishing at about 46 gal. Tea finished at 9 gal. Current estimates for caffeinated energy drinks are on the order of 1 gal/person per year. Apparently, any net caffeine contribution from the caffeinated energy drinks has been roughly balanced by a decrease in coffee and caffeine-containing carbonated beverages.

Energy Drinks: A Caffeine Binge

Thus, it appears the new health problem from energy drinks is not the caffeine per se, but the fact that packaging and marketing entices the user to consume a lot in a short period of time, resulting in a caffeine binge.

Energy drinks and the subset of small-volume products referred to as energy shots grew out of the successes of Red Bull, a European product that reached the United States in 1997. Key ingredients are caffeine at 80 mg and taurine at 2000 mg per 8.3-oz can. From one, many: estimates are that as many as 300 caffeinated “energy” beverages are on the U.S. market, including the energy shot market dominated by 5-hour Energy and an emerging class of pre-workout products intended to improve the exercise experience.

The PepsiCo product amp ENERGY portrays some of the conflicts in characterizing these products. It comes in a 16-oz can described as containing two servings. This product is marketed as an energy supplement, with ingredient amounts in a Supplement Facts panel-yet each serving contains 29 g (110 cal) of sugar, making it more akin to a food. Each serving (remember, two per can) contains 71 mg of caffeine, plus 150 mg of guarana extract, the latter containing an unspecified additional amount of caffeine. Other ingredients include inconsequential amounts of taurine, ginseng, and B vitamins. Two cans, not beyond the thirst-quenching needs of a teenage boy, deliver at least 284 mg of caffeine.

Regulatory Approaches

The energy drink backlash began a few years ago. In 2008, a group of some 100 concerned physicians and research scientists petitioned FDA to establish new regulation to require labeling for caffeine content, limiting the amount of caffeine per serving, and a warning statement on labels and advertising of the health risks of caffeine, especially for groups at higher risk. Review articles delineated adverse effects,(2-5) including adverse effects in children.(6-8)

There are conflicting opinions as to whether caffeine during pregnancy increases risk of miscarriages or preterm births. Women who consume caffeine during pregnancy are also likely to smoke and drink alcohol-known negatives for pregnancy outcomes. So the caffeine may not be causative. In August 2010, the American College of Obstetricians and Gynecologists issued a position paper stating that caffeine consumption below 200 mg/day does not appear to increase risk.(9)

The primary risk appears to be acute intoxication. Symptoms include nausea, vomiting, heart palpitations and arrhythmias, gastrointestinal upset, plus feelings of anxiety and nervousness. Dr. S.M. Siebert, Department of Pediatrics, University of Miami, wrote: “Of the 5448 U.S. caffeine overdoses reported in 2007, 46% occurred in those younger than 19 years.”(8) Most of the energy shot products are aware of the risk and clearly state on the label not to consume more than two a day-and if so, at least several hours apart.

As a Washington-based senior food and drug attorney notes, many of the larger companies have voluntarily taken the step of providing caffeine content on the label. The American Herbal Products Association has long recommended that caffeine content from all sources be labeled. FDA already has the authority to deem caffeine content to be material information under 21 USC 321(n), allowing for mandatory content labeling. Canada already requires this action for energy drinks. The American Beverage Association concurs that caffeine content in milligrams per serving should be clearly labeled, as should a warning statement for at-risk populations plus persons sensitive to caffeine.(10)

In conclusion, the main concern is complications from binge-type consumption. Recommendations for caffeine content are: “Label, limit, and warn.” Labeling for caffeine content-and having that include naturally occurring caffeine in ingredients such as guarana or yerba maté-would help unsuspecting users from unknowingly being exposed to an acute dose far in excess of their typical intake. Paul Dijkstra, CEO of InterHealth Nutraceuticals (Benicia, CA), concurs, “There should be full disclosure…on the label in order for a consumer to make an informed decision.” He added that negative press on the dangers of too much caffeine may pressure FDA to act.

Recommending a daily limit of 400 mg/day (value used by Health Canada) would provide a guideline for what might be considered a safe range, but realistically, tens of millions of people exceed this amount without any apparent ill effects. Warnings would cover the need to limit consumption by young children and pregnant or lactating women.

All the Other Energy Ingredients

More attention and concern have been expressed for caffeine content than for all of the other energy ingredients, combined. Red Bull contains 2000 mg taurine per serving. Taurine is a non-essential amino acid, synthesized from the sulfur-containing amino acids methionine and cysteine. Taurine appears to be safe, but evidence for health or performance benefits is still weak. Guarana and yerba maté are sources of caffeine and other bioactives. Tea, fruit, and berry extracts are sources of flavonoids, a subset of polyphenols associated with antioxidant and other health benefits. Ginseng has traditional usage as a rejuvenator. B vitamins are essential for metabolizing carbohydrates, lipids, and protein for energy. However, there is little evidence that B vitamins in excess of Recommended Daily Intake (RDIs) have any additional benefits. Other than the no-calories energy shots, most of the energy drinks have settled in the neighborhood of 110 cal/serving. This puts them on par with carbonated beverages and lower than 8-oz servings of fruit juices.

The Rise and Fall of CABs

Anyone who has walked into a liquor store in recent years is aware of the shrinkage of the beer display space, to make room for non-beer beverages of similar alcohol content. A few years ago, this niche saw a spectacular rise and fall of caffeinated alcohol beverages (CABs), coming from basically nowhere to a peak in excess of 20 million gallons per year by 2008 before being crushed by FDA.

Caffeine + alcohol = a wide-awake drunk. Caffeine does not speed the absorption of alcohol, nor slow metabolic breakdown. Rather, what caffeine does is mask the depressive effects of alcohol, allowing more alcohol consumption without feeling as drunk. According to the Centers for Disease Control, alcohol contributes to 79,000 deaths per year, with over half of those associated with binge drinking.(11) Behavioral studies clearly showed that combining caffeine with alcohol resulted in more frequent and more severe binge drinking, with the expected consequences: increases in fights, risk-taking behavior, and unprotected, unplanned, or force-involved sexual activity. Many CAB drinkers also believe, mistakenly, that caffeine would preserve their reflexes and visual reaction time, resulting in decisions to drive while they were in fact impaired and legally intoxicated.(12)

In 2008, several state’s district attorneys petitioned FDA to take action against CABs. The response was swift. In November 2009, FDA sent letters to CAB producers, in effect stating that caffeine in an alcohol beverage is not Generally Recognized As Safe (GRAS), and unless the manufacturer can provide evidence of safety, please stop. Everyone stopped.


Research Highlight: Caffeine Interaction

By Jennifer Kwok Grebow, Editor-in-Chief

We know that caffeine, when used responsibly, is safe. But what about caffeine paired with other ingredients? A study published early this year in the International Journal of Medical Sciences concluded that a weight-management supplement containing bitter orange, caffeine, and green tea did not lead to increased cardiovascular stress.(13)

The double-blind, placebo-controlled crossover study was performed on 23 mildly overweight subjects. Over a 24-hour period, subjects consumed four capsules, with each capsule containing: 13 mg of p-synephrine from bitter orange (specifically, Advantra Z, a branded bitter orange ingredient from West Caldwell, NJ-based Nutratech Inc.), 176 mg of caffeine in the form of guarana extract, and 55.5 mg of green tea extract.

Subjects’ heart rate and blood pressure were monitored, as well as expired air. The researchers concluded that the supplement did not affect heart rate, systolic and diastolic blood pressure, or mean arterial pressure. They said blood pressure in hypertensive subjects did not change significantly after supplementation.

Nutratech notes that this study using Advantra Z involved more subjects, as well as multiple rather than a single dose, compared to previous studies involving Advantra Z.



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8. SM Seifert et al., “Health effects of energy drinks on children, adolescents, and young adults,” Pediatrics, vol. 127, no. 3 (March 2011): 511–528.

9. American College of Obstetricians and Gynecologists, "ACOG Committee Opinion No. 462: Moderate caffeine consumption during pregnancy," Obstetrics and Gynecology, vol. 116, no. 2 (August 2010): 467–468.

10. “ABA guidance for the responsible labeling and marketing of energy drinks,” American Beverage Association, accessed August 2011 from:

11. “Caffeinated alcoholic beverages,” Centers for Disease Control, accessed August 2011 from:

12. DL Weldy, “Risks of alcoholic energy drinks for youth,” Journal of the American Board of Family Medicine, vol. 23, no. 4 (July-August 2010): 555–558.

13. J Seifert et al., “Effect of Acute Administration of an Herbal Preparation on Blood Pressure and Heart Rate in Humans,” International Journal of Medical Sciences, vol. 8, no. 3 (published online March 2, 2011): 192–197.