THE SCIENCE BEHIND THE EXPERIMENT
We tested 18 products, including three different brands of each kefir, yogurt, miso, sauerkraut, kimchi and kombucha. Dr. Chapman took 1 milliliter of each product and mixed it for 60 seconds with 9 milliliters of phosphate buffer saline. This homogenized the mixture to ensure that each sample was representative of the total.
The solution was then placed in petri dishes with tomato juice agar, a selective medium for Lactobacilli species —that’s technical speak for ensuring that only the bacteria we wanted to measure was isolated. The plates were then incubated anaerobically, or without oxygen, at 95°F for 48 hours. Then the number of colonies on each plate was counted. (Probiotics are measured in colony forming units, or CFU, which you may recognize from your probiotic supplement.)
We did the experiment twice, took two samples of each product in each experiment, and averaged the numbers for all products in a category. The caveat: We didn’t get results for all products, and we only measured one species, Lactobacilli (we did not account for diversity of strains). We also can’t speak to all brands of products beyond what we tested, as some brands may have more or less probiotics depending on their fermenting process. Having said that, according to Dr. Chapman, this is a pretty good measure of where each of these types of ferments stand.
An image taken under the microscope of individual Lactobacilli organisms from sauerkraut at approximately 1,500 times magnification.