I’ve been writing a lot lately about the health benefits linked to coffee and/or caffeine. So it’s only fair to note that, for all the good it might do us, too much caffeine, at least under some circumstances, can be harmful.

For instance, a report published last week by the Substance Abuse and Mental Health Services Administration (SAMHSA) found a big uptick in the number of emergency-department visits involving consumption of non-alcoholic energy drinks. The American Beverage Association takes issue with the study’s methodology.

In 2009 (the last year for which data are available), the report says, 13,114 people visited hospital EDs for reasons related to energy-drink consumption. That’s up from 1,128 in 2005; the numbers peaked in 2008 at 16,053 — more than 10 times as many ED visits as occurred three years earlier.

Overall, the report says, 45 percent of energy-drink-related ED visits occurred among people ages 18 to 25, and 64 percent of those making such visits were male. Fifty-six percent of the ED visits involved consumption of energy drinks alone, not in combination with prescription drugs, alcohol or other substances, though 10 percent of visits involved energy drinks combined with alcohol, the report says.

The report identifies energy drinks as “flavored beverages containing high amounts of caffeine and typically other additives, such as vitamins, taurine, herbal supplements, creatine, sugars, and guarana, a plant product containing concentrated caffeine.” These drinks, readily available to people of all ages at convenience and grocery stores and any number of other venues, but marketed largely to teens and young adults, typically contain more caffeine than coffee or cola.

According to the report, “The total amount of caffeine in a can or bottle of an energy drink varies from about 80 to more than 500 milligrams (mg) of caffeine, compared with about 100 mg in a 5-ounce cup of coffee or 50 mg in a 12-ounce cola.” Of course, it’s hard to make comparisons without knowing how many ounces of energy drink that can or bottle contains, information I couldn’t find in the report.

The report notes that consuming too much caffeine can cause heart arrhythmias, hypertension, dehydration, sleeplessness and “nervousness” and adds that other problems can occur among people with cardiac conditions, eating disorders, diabetes and anxiety disorders.

The American Beverage Association (representing the non-alcoholic beverage industry) has issued a response noting, among other things, that the report should have placed the number of ED visits in the context of the nearly 124 million annual ED visits in the U.S. and should have emphasized that the number of energy-drink-related ED visits declined from 2008 to 2009. 

"The number of emergency room visits by people who consumed energy drinks, as reported in the paper, represented less than one one-hundredth of one percent of all emergency visits. In addition, this report shares no information about the overall health of those who allegedly consumed energy drinks, or even what symptoms brought them to the ER in the first place. Furthermore, it shows that nearly half of those who visited the emergency room had consumed alcohol or taken illegal substances or pharmaceuticals, making their consumption of energy drinks potentially irrelevant," the ABA statement says.

Here’s a column I wrote last year about whether I should allow my teenage son to enjoy an occasional energy drink. I did allow it — until, as predicted, he completely lost interest in them.