Troops who take dietary supplements to lose weight or get ripped may be getting more caffeine than is healthy, according to a new study published online Monday at JAMA Internal Medicine.

Chemicalanalysis of 31 popular supplements sold on military bases that containcaffeine showed that fewer than half accurately listed caffeine content,with some products containing more caffeine than five 12-ounce MountainDews.

Although the study did not name the products tested, theresearch is important, author Dr. Pieter Cohen said, becauseservicemembers who use supplements probably also consume caffeine fromcoffee, energy drinks and food and may be getting too much of a goodthing.

"Caffeine is extremely safe in the amounts found in food,and research has showed with low to moderate doses, your performance -increased vigilance and decreased reaction time - is better. But likeany drug or medication, get too much of it, and the benefits decrease.At high doses, you are going to have side effects," Cohen said.

Cohen, an assistant professor at Harvard University and internist at Cambridge, Mass.-based Cambridge Health Alliance, teamed with other researchers, including Patricia Deuster with the Uniformed Services University Consortium for Health and Military Performance, on the research.

Thegroup looked at the caffeine content of the 31 top-selling supplementssold at installation exchanges that either listed caffeine as aningredient or probably contained it, based on other ingredients ontheir labels.

Most were weight-loss or workout enhancement supplements, and one was marketed as a multivitamin, Cohen said.

Ofthe 20 products that listed caffeine on their labels, nine containedaccurate amounts, according to the researchers, although "accurate"meant within 10% of the listed amount.

In one case, this meant theproduct, with a label noting it contained 400 mg of caffeine - 11 timesthe amount in a 12-ounce Coke - actually contained 435 mg of caffeine,or the amount found in 12 Cokes.

Five of the products contained far less (27%) or more (113%) caffeine than stated.

Andsix listed caffeine on their labels without any amount noted, as isallowed under Food and Drug Administration regulations. Those six allcontained "high amounts of caffeine ranging from 210 to 310 mg perserving," according to the study.

"This is all legal andlegitimate from a regulatory standpoint, but from a consumer standpoint,it's not helpful. The quantity of caffeine should be clearly stated on alabel and needs to be accurate," Cohen said.

In December, FDAofficials said they were reviewing the safety of energy drinkscontaining caffeine and other stimulants to include an investigation ofadverse reactions to energy drinks and shots as well as consultationswith outside experts, according to the office of Sen. RichardBlumenthal, D-Conn.

In November, the FDA confirmed it had receivedreports of 13 deaths and 92 medical events associated with people whohad taken the popular shot 5-hour Energy.

In October, the FDA also said it was investigating reports of five deaths among those who consumed Monster Energy drinks.

Thereports of adverse health problems after consumption of these energydrinks does not imply that the drinks caused the problems or evencontributed to them, however. It means only that consumers, physicians,medical facilities or the company itself notified FDA of a medicalproblem that occurred either during or after consuming the products.

Cohen said he looked at dietary supplements because he believes they are an overlooked source of caffeine for servicemembers.

Headvised troops to consume caffeine from only well-labeled sources,such as caffeine pills, gum and sodas, all of which are regulated by theFDA.

"We don't want to throw caffeine under the bus. Caffeine is asafe, fantastic ingredient. ... I would avoid supplements that listcaffeine in any amount on their labels. Combining them with energydrinks or any other caffeinated product could be detrimental to yourhealth," he said.