The Impact of Synbiotic Yogurt Consumption on Insulin-Resistance Surrogates, Atherogenic and Novel Anthropometric Indices in Adults With Metabolic Syndrome: A Randomized Clinical Trial Publisher

Summary: Does synbiotic yogurt improve metabolic syndrome? A 12-week trial found no significant improvement in key metabolic risk measures. #MetabolicSyndrome #Nutrition

Jowshan M R ; Zolghadrpour M A ; Imani H ; Rahmanian R ; Karimpour F ; Hamedi Shahraki S ; Amirkhizi F ; Asghari S
Source: Nutrition and Metabolism Published:2026

Abstract

Background: Metabolic syndrome (MetS) represents a well-recognized contributor to cardiovascular risk, and synbiotics have recently gained attention as a potential dietary strategy for its management. The present study aimed to determine whether a novel synbiotic yogurt formulated with Lactobacillus plantarum, Lactobacillus pentosus, and the yeast Kluyveromyces marxianus affects atherogenic markers, cardiometabolic parameters, and insulin resistance surrogates in individuals among individuals diagnosed with MetS. Methods: A 12-week double-blind, standard-yogurt-controlled randomized clinical trial was conducted, enrolling 44 adults with MetS who were randomized to either 300 g/day of synbiotic yogurt (n = 22) or a matched control yogurt (n = 22); 41 (22 synbiotic, 19 control yogurt) completed and were analyzed. A comprehensive panel of cardiometabolic outcomes was evaluated at baseline and week 12, encompassing atherogenic indices including the Atherogenic Index of Plasma (AIP), Castelli’s Risk Index-I (CRI-I), Castelli’s Risk Index-II (CRI-II), Atherogenic Coefficient (AC), and oxidized low-density lipoprotein (ox-LDL); cardiometabolic measures including the Visceral Adiposity Index (VAI), Waist Triglyceride Index (WTI), and Cardiometabolic Index (CMI); body shape and adiposity indices including A Body Shape Index (ABSI), Body Roundness Index (BRI), Body Adiposity Index (BAI), Conicity Index, Abdominal Volume Index (AVI), and Weight-adjusted Waist Index (WWI); and surrogate markers of insulin resistance including the Triglyceride-Glucose Index (TyG), Hepatic Steatosis Index (HSI), triglyceride to high-density lipoprotein ratio (TG/HDL), TyG-Body Mass Index (TyG-BMI), TyG-Waist Circumference (TyG-WC), Metabolic Score for Insulin Resistance (METS-IR), and Lipid Accumulation Product (LAP). Results: At the end of the 12-week period, statistically significant between-group differences were limited to four indices, namely CRI-I (p = 0.039), CRI-II (p = 0.038), AC (p = 0.039), and BAI (p = 0.027), all of which favored the control group. Within-group analyses indicated that the control arm experienced significant reductions in AIP, CRI-I, CRI-II, AC, TG/HDL, and METS-IR, whereas participants in the synbiotic arm demonstrated significant decreases only in TyG and TyG-BMI. No significant changes were observed in other indices. Conclusions: According to our findings, 12 weeks of daily synbiotic yogurt consumption did not significantly improve insulin resistance surrogates, atherogenic, and novel anthropometric indices in adults with MetS. Trial registration number: Iranian Registry of Clinical Trials (registration ID: IRCT20220426054667N1; registration date: 2022-05-18). © The Author(s) 2026.