Consumption of probiotic yogurt and vitamin D‐fortified yogurt increases fasting level of GLP‐1 in obese adults undergoing low‐calorie diet: A double‐blind randomized controlled trial

Energy restriction and manipulation of macronutrient composition of the diet are the main approaches that are used by people who aim to lose weight. When such strategies are employed, appetite and endocrine regulators of satiety, such as gut peptides, all are deeply affected. The gut microbiota–brain axis controls energy homeostasis in humans by affecting central satiety and gut peptides. The purpose of this study was to evaluate if the synergistic effect of probiotics and vitamin D in yogurt matrix can modulate this effect. In the double‐blind, randomized, placebo‐controlled trial, 140 obese adults were randomly allocated into four groups: 1) regular yogurt plus low‐calorie diet; 2) PY plus low‐calorie diet; 3) vitamin D‐fortified yogurt plus low‐calorie diet, and 4) probiotic and vitamin D co‐fortified yogurt plus low‐calorie diet. All groups were encouraged to increase their physical activity. Glucagon‐like peptide‐1 (GLP‐1), peptide Tyrosin‐Tysrosin (PYY), ghrelin, anthropometric variables, insulin, fasting blood sugar (FBS), insulin resistance/sensitivity, 1,25(OH)(2) D(3), dietary intake, and physical activity were measured before and after 10 weeks. The difference between groups for GLP‐1 after 10 weeks was significant after adjusting for baseline GLP‐1 and protein intake as confounders. PY showed the largest effect size (ES) on GLP‐1 (p = 14.2) and FBS (p = 14) compared with others. Pairwise comparison of yogurts effect sizes on GLP‐1 showed a significant difference in group 1 vs. group 2 (p = .001), group 1 vs. group 3 (p = .003), and group 1 vs. group 4 (p = .048). Vitamin D‐fortified yogurt had the largest effect size on the serum level of vitamin D and it showed a significant difference with RY (p = .018) and PY (p = .002). Consumption of vitamin D‐fortified yogurt and PY could be regarded as a promising approach during calorie restriction.