The amount of caffeine in diet supplements varies widely and product labels are often inaccurate or have no caffeine information at all, according to a new study of supplements sold on military bases.
Although the caffeine doses probably wouldn't be a problem on their own, they may cause issues when the pills or powders are combined with energy drinks, coffee and other high-caffeine food and beverages, researchers said.
"Consumers really have no idea when they're purchasing supplements what's in them, even if they carefully read the label," said Dr Pieter Cohen from Harvard Medical School in Boston, who worked on the new study.
He and his colleagues analysed the caffeine content of 31 dietary supplements sold on military bases that are known to have added caffeine or herbal ingredients that naturally contain caffeine.
What the study found
Eleven of the supplements listed herbal ingredients, and all of those had no caffeine or only minimal traces, the research team reported.
Among the other 20 products, nine had labels with accurate caffeine information. Another five had varying caffeine contents that were either much lower or higher than the amount listed on the label.
The remaining six products did not have caffeine levels on their labels, but had very high amounts according to the chemical analysis - between 210 and 310 mg per serving. In comparison, an eight-ounce cup of coffee has about 100 mg of caffeine.
Those levels are especially worrisome for military service members abroad, he said, because side effects of caffeine such as tremors and anxiety may hit them extra hard due to the stressful environment.
Lack of information
Too much caffeine, according to Dr Cohen, "could push one over from just being a little on edge to having a full-blown panic attack."
One limitation of the study was that the researchers only tested one sample of each supplement. Because of that, Dr Cohen said it wouldn't be right to call out any single company on its products.
What stood out to him was how common inaccurate labelling or lack of information was, across the board.
"When we look at the totality of products that have caffeine in them that are consumed on military bases, half the bushel is rotten," he said.
A spokesperson for GNC, which produces and sells diet and nutritional supplements, said in an email, "We believe that all GNC brand labelling is appropriate as to ingredients and dosage. GNC does, like many other retailers, sell third party products and questions on their labelling practices should be addressed directly to those manufacturers."
Dr Cohen said the laws for regulating supplements are "inadequate," but that the US Food and Drug Administration (FDA) also isn't doing a good enough job enforcing the labelling regulations that do exist.
The FDA public affairs office did not respond to requests for comment before press time.
Dr Cohen recommended that non-military members also avoid supplements that list caffeine on the label - since it's hard to know just how much of it they actually contain.
(Reuters Health, January 2013)
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