The effect of Nigella sativa on TAC and MDA in obese and overweight women: secondary analysis of a crossover, double blind, randomized clinical trial.

Purpose: Since obesity is a risk factor for various diseases and is associated with increased oxidative stress conditions, some herbs are considered to be effective in reducing obesity and its complications.
Methods: This secondary analysis investigates the effect of Nigella sativa (N.S) oil supplement on total antioxidant capacity (TAC) and malondialdehyde (MDA) levels in obese/overweight women. Obese and overweight healthy women were randomized to receive 2,000 mg/d of N.S supplement and placebo. The intervention periods lasted 8 weeks and were separated by a 4-week washout period. Also, each participant was given an iso-calorie diet. Baseline characteristics and TAC and MDA levels were measured. Pkcross analysis was performed for statistical analysis using Stata software. Also, Cohen's d was estimated as effect size for all results to assess the magnitude of the effects.
Results: 39 women completed the study. N.S oil supplementation at a dose of 2000 mg/d significantly increased serum TAC (P effect = 0.017, Cohen's d = 1.81) and reduced serum MDA (P effect < 0/001, Cohen's d =  - 0.32).
Conclusion: Based on our findings taking N.S supplementation for 8 weeks can improve antioxidant conditions in obese and overweight adults. However, more studies with a larger population and the presence of both genders need to be done to confirm the results.Registration number: IRCT20180430039475N1. © Springer Nature Switzerland AG 2022.