A fermentation product of Cordyceps sinensis increases whole-body insulin sensitivity in rats

Objective: CordyMax(TM) Cs-4 (Cs-4) is a standardized mycelial fermentation product of Cordy-ceps sinensis, a fungus that has been used for various pharmacologic, metabolic, and ergogenic purposes. The goal of this investigation was to determine the effects of oral Cs-4 administration on whole-body insulin sensitivity, skeletal muscle glucose transport, and endurance performance. Design: We studied different indices of carbohydrate metabolism in rats that received Cs-4 orally at a dose of 2 g/kg of body weight daily for 30 days. Results: C-peptide response observed during the oral glucose tolerance test (OGTT) after 10 days of treatment was significantly decreased in the Cs-4-treated group (Cs-4, 52,802 +/- 4,124 vs. control, 70,696 +/- 6309 pM x 120 min; p < 0.05). The integrated insulin area under the curve (53.3 +/- 4.9 ng/mL x 120 minutes) and the glucose-insulin index (6.6 +/- 0.6 units) obtained from the OGTT were significantly decreased (p < 0.01) in the Cs-4-treated group compared to their vehicle-treated counterparts (82.1 +/- 8.1 ng/mL x 120 minutes; 9.9 +/- 0.7 units) after 20 days of treatment. Neither integrated glucose area under the curve observed during either OGTT, basal- or insulin-stimulated 2-deoxyglucose transport nor skeletal muscle GLUT-4 concentrations were affected by Cs-4 treatment. In addition, swim time to exhaustion did not differ between groups in this animal model. Conclusion: We conclude that CordyMax Cs-4 may have potential beneficial effects by maintaining whole-body glucose disposal with a less pronounced increase in insulin secretion after a carbohydrate challenge, however, its effects on endurance performance remain questionable.