Acute and subchronic toxicity of FCD, a soybean extract combined with l-carnitine, in Sprague–Dawley rats

Soy products are primarily composed of proteins, phytochemicals such as isoflavones, soy lipids, and carbohydrates. Recently, soy isoflavones with l-carnitine were reported to exhibit anti-obesity effects in mice. FCD, a combination of soybean extract and l-carnitine, is a newly developed food substance. As a part of its safety assessment, acute and 13-week subchronic toxicity studies were performed in a total of 100 Sprague–Dawley (SD) rats. In the acute study, a single limit dose of 2000 mg/kg was orally administered to five male and five female rats. No adverse effects or mortality was observed during a 14-day period or upon gross pathological examination. In the subchronic study, FCD was orally administered in daily doses of 500, 1000, and 2000 mg/kg for 13 weeks, resulting in no mortality, and no changes in hematological and serum biochemistry parameters, gross pathology or histopathology. However, body weights of females were significantly decreased 10 weeks after treatment at an average of 2000 mg/kg. In addition, a slight decrease in mean food and water consumption was observed at the same dose level for 13 weeks. Therefore, the no-observed-adverse-effect-level (NOAEL) of FCD was considered to be 2000 mg/kg for male and 1000 mg/kg for female SD rats.