When shopping for soda, it’s a reasonable assumption that store-brand colas have more or less the same amount of caffeine as the name brand, right? Or at least the same amount of caffeine from one bottle to another. Some scientists studied a wide variety of sodas, tested their caffeine levels and learned…not so much.

In the context of the pro-generic medicine stance that Consumerist took in this post about the McNeil plant that produced bacteria-ridden medicine for kids, reader Todd sent us a study published in the Journal of Food Science in 2007. The data may be a little out of date, but it’s not flat yet. It’s fascinating. The study found that while name-brand sodas were pretty consistent in their caffeine content, store-brand drinks weren’t. Some of Food Lion’s version of Mountain Dew didn’t have any caffeine at all, entirely defeating the point.

Based upon the standard deviations listed in Table 3 to 6, the quality control of national-brand beverages appeared generally better than that for the store-brand beverages. Additional lots were obtained and analyzed for some beverages whose duplicate lots had quite different caffeine values. Products displaying large variations between lots included Rite Aid’s Big Fizz Cola, Walgreens Cola, Walgreens Diet Cola, Dollar General’s CloverValley Cola, CloverValley Diet Cola, Save-a-Lot’s Dr Pop, Winn-Dixie’s Chek Diet Kountry Mist, and Ingle’s Laura Lynn Mountain Moon Drop. In addition, 1 lot of Food Lion’s Mountain Lion was found to contain no caffeine (this sample was not included in the data analysis). Thus, there appears to be less stringent quality control with store-brand products than with the national-brand products.

Caffeine content of prepackaged national-brand and private-label carbonated beverages. (Abstract only) [PubMed]

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