A new peer-reviewed study from researchers at the University of Illinois and Ohio State University found 66% of commercial kefir products overstated probiotic count and “contained species not included on the label.”
Kefir, widely consumed in Europe and the Middle East, is growing in popularity in the U.S. Researchers examined the bacterial content of five kefir brands. Their results, published in the Journal of Dairy Science, challenge the “probiotic punch” the labels claim.
“Our study shows better quality control of kefir products is required to demonstrate and understand their potential health benefits,” says Kelly Swanson, professor in human nutrition in the Department of Animal Sciences and the Division of Nutritional Sciences at the University of Illinois. “It is important for consumers to know the accurate contents of the fermented foods they consume.”
Probiotics in fermented products are listed in colony-forming units (CFUs). The more probiotics, the greater the health benefit.
According to a news release from the University of Illinois: “Most companies guarantee minimum counts of at least a billion bacteria per gram, with many claiming up to 10 or 100 billion. Because food-fermenting microorganisms have a long history of use, are non-pathogenic, and do not produce harmful substances, they are considered ‘Generally Recognized As Safe’ (GRAS) by the U.S. Food and Drug Administration and require no further approvals for use. That means companies are free to make claims about bacteria count with little regulation or oversight.”
To perform the study, the researchers bought two bottles of each of five major kefir brands. Bottles were brought to the lab where bacterial cells were counted and bacterial species identified. Only one of the brands studied had the amount of probiotics listed on its label.
“Just like probiotics, the health benefits of kefirs and other fermented foods will largely be dependent on the type and density of microorganisms present,” Swanson says. “With trillions of bacteria already inhabiting the gut, billions are usually necessary for health promotion. These product shortcomings in regard to bacterial counts will most certainly reduce their likelihood of providing benefits.”
The news release continues:
When the research team compared the bacteria in their samples against the ones listed on the label, there were distinct discrepancies. Some species were missing altogether, while others were present but unlisted. All five products contained, but didn’t list, Streptococcus salivarius. And four out of five contained Lactobacillus paracasei.
Both species are common starter strains in the production of yogurts and other fermented foods. Because those bacteria are relatively safe and may contribute to the health benefits of fermented foods, Swanson says it’s not clear why they aren’t listed on the labels.
Although the study only tested five products, Swanson suggests the results are emblematic of a larger issue in the fermented foods market.
“Even though fermented foods and beverages have been important components of the human food supply for thousands of years, few well-designed studies on their composition and health benefits have been conducted outside of yogurt. Our results underscore just how important it is to study these products,” he says. “And given the absence of regulatory scrutiny, consumers should be wary and demand better-quality commercial fermented foods.”