CONSUMPTION OF A PHENOLIC-RICH SORGHUM BEVERAGE IMPROVES GLYCEMIC HOMEOSTASIS IN ADULTS WITH OBESITY: A SINGLE-BLIND, RANDOMIZED, PLACEBO-CONTROLLED STUDY

INTRODUCTION: Sorghum (Sorghum bicolor) is an excellent dietary source of bioactive compounds. Its phenolic-rich matrix has been associated with beneficial effects on glucose metabolism through antioxidant and anti-inflammatory mechanisms. However, evidence from randomized clinical trials evaluating chronic sorghum consumption on postprandial glycemic response in adults with excess body weight remains limited. OBJECTIVE: To evaluate the effects of ten weeks of daily consumption of a phenolic-rich sorghum beverage on postprandial glycemic response in adults with excess body weight.  METHODS: A single-blind, randomized, placebo-controlled clinical trial was conducted in adults with overweight and obesity. Body weight, height, body mass index (BMI), waist circumference, body fat percentage, and fasting blood glucose were assessed at baseline and week 10. Participants were allocated to consume either a phenolic-rich sorghum beverage or an isocarbohydrate control beverage daily for 10 weeks and were stratified according to BMI into four groups: sorghum-overweight (n=10), sorghum-obesity (n=15), control-overweight (n=11), and control-obesity (n=15). Postprandial glycemic response was assessed at baseline and after the intervention by measuring capillary blood glucose at fasting and at 15, 30, 45, 60, 90, and 120 min. Glycemic response was analyzed using a linear mixed-effects model considering group, intervention, and sampling time. The incremental area under the glucose curve (iAUC), peak blood glucose concentration, time to peak glucose, and maximum glucose increment were calculated and compared using Student's t-test. The study was approved by the Ethics Committee of the Federal University of Viçosa (CAAE: 53827321.4.0000.5153) and registered in the Brazilian Registry of Clinical Trials (RBR-32v2gm5). RESULTS: A total of 51 adults with excess body weight completed the study. Among participants with obesity, the sorghum group exhibited lower blood glucose concentrations at 45, 60, and 90 min compared with the control group (p<0.001). In addition, the sorghum group showed lower iAUC than the control group at the endpoint (p=0.014), accompanied by lower peak blood glucose concentration (p=0.034), lower maximum glucose increment (p=0.009), and a longer time to peak glucose (p=0.011). No differences in postprandial glycemic parameters were observed for the overweight groups (p>0.05). Furthermore, no changes in BMI, waist circumference, body fat percentage, and fasting blood glucose were observed after the 10-week intervention in any of the study groups. DISCUSSION: The improvement in postprandial glycemic response despite unchanged fasting glucose highlights the importance of postprandial measures for detecting early metabolic benefits of dietary interventions. The observed effects may be attributed to the phenolic compounds in sorghum, which have been associated with reduced carbohydrate digestion and glucose absorption. CONCLUSION: Daily consumption of a phenolic-rich sorghum beverage for ten weeks improved postprandial glycemic response in adults with obesity, supporting the metabolic potential of sorghum-derived bioactive compounds as part of dietary strategies for glycemic management. ACKNOWLEDGMENTS: This study was supported by FAPEMIG, CNPq, and CAPES.