The 36 young, sedentary male participants in this study were divided into three groups: Exercise only (12 participants) - Aerobic exercise; Exercise + Boza (12 participants) - aerobic exercise plus 300 mL/day boza (a traditional Turkish yeast-fermented grain beverage); Exercise + Kefir (12 participants) - aerobic exercise plus 300 mL/day kefir. Blood was drawn before and after the intervention, and, for each group, the study authors did a "before-and-after" comparison of 19 blood values, without correcting for multiple comparisons.
They found that the serum levels of alanine aminotransferase (ALT) and total oxidant status (TOS) were significantly reduced in the exercise + kefir group; the serum levels of triglycerides, very-low-density lipoproteins (VLDL), creatinine, and chlorine (Cl) were significantly reduced in the exercise + boza group; and no blood parameters were significantly reduced in the exercise-only group.
The authors used a statistical test to compare the exercise+(kefir/boza) groups to the exercise-only group, but didn't include the results of that test in the paper. Between that omission, the small sample size, and the lack of statistical correction for multiple comparisons, these findings should be treated as preliminary.
Note: The kefir used in this study was commercial Turkish kefir produced by Atatürk Orman Çiftliği.