Safety of a Coleus forskohlii formulation in healthy volunteers

Abstract

Coleus forskohlii (CF) is an Indian plant that has been used in Ayurvedic medicine. Several trials have reported the weight-loss effects of CF extract. We investigated the safety and efficacy of CF extract (Forskohlii, DHC Corporation) in healthy volunteers. A dose escalation study was performed to determine the type and frequency of adverse events. Twenty-nine healthy subjects were recruited in an open-label trial and were administered escalating doses from 250 to 1000 mg over a 4-week period. Patients were examined on a daily basis for adverse events. Blood, urine, and stool samples were obtained before and after supplementation in a subset of 10 subjects to assess the safety of the supplement. All 29 subjects completed the study. Intake of CF was associated with minor gastrointestinal adverse events such as soft stool and diarrhea, which appeared to be dose-related. There were no major adverse events. At each dose of CF, either 6 or 7 subjects reported minor GI events. C. forskohlii formulation appears to be well tolerated in daily oral doses up to 1000 mg, and warrants further investigation for its efficacy as a long-term anti-obesity intervention. This study was registered at http://www.umin.ac.jp, as UMIN000008224.