Nigella sativa oil with a calorie-restricted diet can improve biomarkers of systemic inflammation in obese women: A randomized double-blind, placebo-controlled clinical trial

Background: Inflammation is one of the primary mechanisms in the development of metabolic complications. Although anti-inflammatory characteristics of Nigella sativa (NS) have been indicated in animal models, clinical trials related to the effects of NS on inflammatory parameters are relatively scarce.

Objective: The aim of the present study was to determine the effects of NS oil combined with a calorie-restricted diet on systemic inflammatory biomarkers in obese women.

Methods: In this double-blind placebo-controlled randomized clinical trial, 90 volunteer obese (body mass index = 30-34.9 kg/m(2)) women aged 25-50 years were recruited. Participants were randomly divided into two groups, an intervention group (n = 45) and a placebo group (n = 45). Each group received either: (1) a low-calorie diet with 3 g/day of NS oil or (2) a low-calorie diet with 3 g/day placebo for 8 weeks.

Results: A total of 84 females (intervention group = 43; placebo group = 41) completed the trial. Subjects in the intervention group did not report any side effects with the NS oil supplementation. NS oil decreased serum levels of tumor necrosis factor-alpha (-40.8% vs -16.1%, P = .04) and high-sensitivity C-reactive protein (-54.5% vs -21.4%, P = .01) compared to the placebo group. However, there were no significant changes in interleukin-6 levels (-8.6 vs -2.4%, P = .6) in the NS group compared to the placebo group.

Conclusions: NS oil supplementation combined with a calorie-restricted diet may modulate systemic inflammatory biomarkers in obese women. However, more studies are needed to clarify the efficacy of NS oil as an adjunct therapy to improve inflammatory parameters in obese subjects.