Dive Summary:

• The study, published in the Journal of the American Medical Association, found that the majority of labeling on caffeine containing supplements was inaccurate.
• This came as a shock to researchers, as labeling and dietary regulations are already quite lenient for products marketed as supplements.
• Out of 20 products tested, 9 were within 10% of the caffeine listed, 5 were much farther off with caffeine content ranging from 27% - 113% of the listed value.  The last six only had caffeine listed in the ingredients, but all contained a surprising large amount of it.

From the article:

Fewer than half the caffeine supplements sold on military installations accurately list the amount of caffeine they contain, according to a new study.