Effect of Nigella Sativa Oil Extract on Leptin and adiponectin in type 2 diabetic patients: A Randomized, Double Blind, Placebo controlled Clinical Trial

The effects of herbal medicine in management of chronic diseases such as diabetes are under investigation. One of the most recent herbal medicine to management of diabetes is nigella Sativa. The mechanism of the effect of nigella Sativa on diabetes is not clear. One of the mechanisms that improves insulin resistance among type 2 diabetes is an increase in adiponectin concentration and a decrease in serum leptin concentration, but few studies have examined the effect of nigella Sativa on leptin and adiponectin concentrations. The aim of this double-blind randomized controlled clinical trial was to investigate the effect of nigella Sativa oil extract on serum leptin and adiponectin concentrations in patients with type 2 diabetes mellitus.

Forty-three type 2 diabetic patients, aged 30-55 years (20 women, age: 53.7±6.3 years) were randomly assigned to groups designated to the intervention (n=23) and the control (n=20) groups. Intervention group consumed 2 capsules daily, (500 mg extract of black seed oil), while control group consumed 2 capsules (500 mg, placebo), both for 8 weeks. Leptin and adiponectin concentrations were measured at baseline and again after the 8-week intervention. To calculate changes in leptin and adiponectin, baseline and end-of-intervention values were used to compare baseline and end-of-intervention values in each group, using the paired t-test.

Extract of black seed oil significantly decreased leptin concentrations in the intervention group (baseline 7.3±0.6; after intervention 5.2 ± 0.3, p < 0.005) compared to the control group (baseline 7.6 ± 0.9, after intervention 7.8 ± 0.9, p=0.41). There was no significant change in adiponectin concentrations after both Nigella Sativa Oil Extract and placebo consumption.

It seems that Nigella Sativa Oil Extract reduces serum leptin concentrations in type 2 diabetic patients, however no significant effect on adiponectin concentrations was found.