The adverse effects of long-term l-carnitine supplementation on liver and kidney function in rats

Levo-Carnitine (l-carnitine) is widely used in health and food. This study was to focus on the adverse effects of 8-week oral supplementation of l-carnitine (0.3 and 0.6 g/kg) in female and male Sprague Dawley rats. l-carnitine reduced body and fat weights, as well as serum, liver, and kidney lipid levels in rats. Simultaneously, hepatic fatty acid β-oxidation and lipid synthesis were disturbed in l-carnitine-fed rats. Moreover, l-carnitine accelerated reactive oxygen species production in serum and liver, thereby triggering hepatic NOD-like receptor 3 (NLRP3) inflammasome activation to elevate serum interleukin (IL)-1β and IL-18 levels in rats. Alteration of serum alkaline phosphatase levels further confirmed liver dysfunction in l-carnitine-fed rats. Additionally, l-carnitine may potentially disturb kidney function by altering renal protein levels of rat organic ion transporters. These observations may provide the caution information for the safety of long-term l-carnitine supplementation.