Functional Food Potential of White Tea: Targeting GREM1 Expression and Metabolic Dysregulation in Obesity

Background: Obesity is a major global health concern, being associated with insulin resistance and multiple metabolic disorders. Gremlin 1(GREM1), a bone morphogenetic protein(BMP) antagonist, is increasingly recognised as a key regulator of adipose tissue dysfunction and impaired thermogenesis in obesity. White tea has demonstrated antioxidant and anti-obesity properties in experimental models. The aim of this study was to evaluate the effects of white tea on metabolic parameters and GREM1 expression in rats made obese by a high-fat diet (HFD). Methods: A total of 40 male Sprague-Dawley rats were randomised into five groups: a standard diet group (STD); a high-fat diet group (HFD); an HFD + orlistat group (HFD + ORL); an HFD + 50 mg/kg white tea group (HFD + WT50); and an HFD + 150 mg/kg white tea group (HFD + WT150). Obesity was induced by feeding the rats a 45% high-fat diet for 3 weeks. Serum insulin, glucose and HOMA-IR levels were measured. Levels of GREM1 and BMP4 in serum and retroperitoneal adipose tissue were assessed. Results: White tea supplementation, significantly reduced weight gain and HOMA-IR compared to the HFD group. GREM1 mRNA expression in visceral adipose tissue decreased markedly in the WT50 and WT150 groups (p = 0.002 and p = 0.017, respectively). Serum GREM1 levels were significantly lower in the white tea-treated groups than in the HFD group (p = 0.011). Tissue BMP4 levels were only significantly reduced in the WT50 group (p = 0.005). There was a negative correlation between serum BMP4 levels and weight gain (rho = –0.440, p = 0.015). Conclusion: White tea has been shown to have a protective metabolic effect in obese rats, suppressing GREM1 expression and improving insulin sensitivity. White tea could therefore serve as both a dietary antioxidant and a molecular regulator of adipose tissue function in obesity management.