Efficacy and safety of Elaeis guineensis and Ficus deltoidea leaf extracts in adults with pre-diabetes

Individuals with pre-diabetes (fasting glucose 100–125 mg/dl) are at increased risk of developing diabetes; 50% of U.S. adults aged ≥65 y had pre-diabetes in 2005–08. Extracts of the leaves of E. guineensis (a tropical plant producing edible oil), and F. deltoidea (a traditional tea) contain phenolic compounds that have hypoglycemic effects in vitro and in vivo. Therefore, a study of the efficacy and safety of these leaf extracts was undertaken.

Otherwise healthy adults with pre-diabetes (15m/15f; aged 21 to 65 y; BMI ≥25 and < 40 kg/m²) were assigned to one of 3 groups for 8 weeks: E. guineensis leaf extract 500 mg or 1000 mg or F. deltoidea leaf extract 1000 mg. Assessments at baseline and throughout the study included: fasting plasma glucose, insulin, OGTT, and HOMA-IR; body weight and waist circumference; vital signs, comprehensive metabolic and lipid panels. Statistical analyses included paired Student’s t-test and ANCOVA or non-parametric tests when indicated.

E. guineensis intervention for 8 weeks decreased fasting plasma glucose and insulin levels, glucose and insulin areas under the curve, and insulin resistance, and increased insulin sensitivity. The 500 mg dose of E. guineensis had a more consistent effect on reducing glycemia than the 1000 mg dose and the insulin findings at the two dose levels were somewhat inconsistent. Differences in the distribution of baseline insulin levels in the low and high dose groups may explain some of these observed differences in responses. F. deltoidea leaf extract had no effect on glycemia variables but both total and LDL cholesterol concentrations were significantly decreased in this group. There were no significant differences in change of weight; however waist circumference was significantly lower in the E. guineensis groups after intervention. At baseline and after 8 weeks of intervention, vital signs and safety lab tests were within normal limits and not significantly different between groups or due to intervention.

These results suggest that the leaf extracts of E. guineensis and F. deltoidea may have positive effects on glucose and lipid levels and are safe for use in humans. Further study is required to determine the maximum effective dosages and the mechanisms of action.