Licorice flavonoid oil effects body weight loss by reduction of body fat mass in overweight subjects

Licorice flavonoid oil (LFO) is a new dietary ingredient for functional foods consisting of licorice hydrophobic polyphenols in medium-chain triglycerides (MCT). In an effective dose finding study conducted previously, LFO has exhibited a dose-dependent body fat-reducing effect. Here we report the weight-reducing effect of LFO in a placebo-controlled, double-blind, long-term (12 weeks) ingestion study at 300 mg/day, the minimal effective dose observed in the dose finding study. A total of 103 overweight subjects [body mass index (BMI): 24-30] completed this study and were analyzed. Body weight increased in the placebo group, but was maintained at close to pre-ingestion level in the LFO group, resulting in significant (p < 0.05) differences in the changes in body weight and between the LFO group and the placebo group at each time-point. Dual-energy X-ray absorptiometry (DXA) measurement of body fat indicated that the weight-reducing effect was attributable to reduced body fat. No clinically significant adverse events occurred during the 12-week ingestion period. To confirm the safety of LFO for practical use we also conducted a placebo-controlled, double-blind safety study in 40 overweight subjects with a 4-week excessive ingestion at 1800 mg/day; 6 times the dose of the 300 mg/day study that exhibited a weight-reducing effect. No clinically significant adverse events occurred during the 4-week ingestion period. Based on these findings in both human studies it was shown that LFO is a safe ingredient for functional foods even for long-term or excessive ingestion, with a potential weight-reducing effect.