Consumption of Sericin Enhances the Bioavailability and Metabolic Efficacy of Chromium Picolinate in Rats

The effects of silk sericin (SS) supplementation on the functionality of chromium picolinate (CrPic) and lipid metabolism were assessed in male Sprague-Dawley rats to determine whether SS improves the bioavailability of CrPic and contributes to beneficial changes in lipid profiles and cardiovascular risk markers. Rats were administered different doses of SS (0, 1, 10, and 100 mg kg^-1 body weight (BW)) in conjunction with CrPic (300 µg kg^-1 BW) for 8 weeks through oral gavage. Body and organ weights, lipid profiles, glucose levels, chromium (Cr) accumulation, total protein, and adipocyte size were evaluated. Additionally, FTIR analysis was conducted to investigate the binding and release behavior of SS with CrPic. Although body weight and daily feed intake were comparable among groups, a significant increase in pancreas weight and reduction in omentum weight were observed across all CrPic-SS groups. Increased dosages of SS resulted in a significant reduction in triglyceride and plasma glucose levels. All CrPic and CrPic-SS treatments reduced LDL and total cholesterol while increasing HDL. Cr accumulation was elevated in the liver and kidneys of groups administered 10 and 100 mg kg^-1 BW of SS, accompanied by a significant increase in total protein levels and a reduction in adipocyte size to less than 50 µm in all rats. FTIR analysis indicated that SS binds to CrPic at pH 2.0 and releases it at pH 7.0, demonstrating pH-dependent delivery similar to the gastrointestinal tract and possibly improved CrPic functionality. These findings indicate that SS improves the bioavailability of CrPic and positively affects lipid metabolism and cardiovascular risk markers in vivo.