Effects of kefirs on glycemic, insulinemic and satiety responses
We hypothesized that three types of kefir (Lifewayy Low Fat Strawberry Kefir, ProBugs Kefir, orange flavor, and Lifewayy Low Fat Plain Kefir) would have low glycemic index (GI), high insulinemic index (II) and high satiety index (SI). Secondarily, we hypothesized that there would be no significant correlations among postprandial satiety, glucose and insulin responses. Lastly, we hypothesized that kefir, like other dairy products, would have dissociation of GI and II. To test our hypotheses, this study was divided into three phases. In Phase I, a portion of Lifewayy Low Fat Strawberry Kefir (S group) and a portion of ProBugs Kefir, orange flavor (O group) containing 50 g of available carbohydrates were tested. In Phase II, a portion of Lifewayy Low Fat Plain Kefir (P group) containing 25 g of available carbohydrates were tested. In Phase III, 240-kcals portions of all three types of kefirs were tested. In all phases a single meal, randomized crossover design was performed in which the test meals were fed to 10 healthy, male and female adults. The total glucose AUC of S group (p< 0.0023), O group (p< 0.0002) and P group (p< 0.0002) were significantly lower compared with their respective glucose controls. A slight, but not significant inverse relationship between glycemic and satiety responses was observed with kefir beverages (r = -0.87; P = 0.13). Using a variance of component analysis, it was found that in the future, a significant relationship between the correlated effects of the treatments on GI and SI can be further tested by increasing the number of subjects to 12. Like other dairy products, kefir showed a dissociation of GI and II. Kefir can potentially be a useful food choice for patients with diabetes who are required to control their blood glucose levels.