Kefir reduces insulin resistance and inflammatory cytokine expression in an animal model of metabolic syndrome

There is growing evidence that kefir can be a promising tool in decreasing the risk of many diseases, including metabolic syndrome (MetS). The aim of the present study was to evaluate the effect of kefir supplementation in the diet of Spontaneously Hypertensive Rats (SHR) in which MetS was induced with monosodium glutamate (MSG), and to determine its effect on metabolic parameters, inflammatory and oxidation marker expression and glycemic index control. Thirty animals were used in this experiment. For the induction of MetS, twenty two-day-old male SHR received five consecutive intradermal injections of MSG. For the Negative Control, ten newborn male SHR received intradermal injections of saline solution (0.9% saline solution). After weaning, animals received standard diet and water ad libitum until reaching 3 months old, for the development of MetS. They were then divided into three groups ( n = 10): negative control (NC, 1 mL saline solution per day), positive control (PC, 1 mL saline solution per day) and the Kefir group (1 mL kefir per day). Feeding was carried out by gavage for 10 weeks and the animals received standard food and water ad libitum. Obesity, insulin resistance, pro- and anti-inflammatory markers, and the histology of pancreatic and adipose tissues were among the main variables evaluated. Compared to the PC group, kefir supplementation reduced plasma triglycerides, liver lipids, liver triglycerides, insulin resistance, fasting glucose, fasting insulin, thoracic circumference, abdominal circumference, products of lipid oxidation, pro-inflammatory cytokine expression (IL-1β) and increased anti-inflammatory cytokine expression (IL-10). The present findings indicate that kefir has the potential to benefit the management of MetS. Kefir supplementation in rats with induced metabolic syndrome was able to lower fasting glucose, fasting insulin levels, and reduce insulin resistance.