The efficacy of Nigella sativa L. oil on serum biomarkers of inflammation and oxidative stress and quality of life in patients with knee osteoarthritis: A parallel triple‐arm double‐blind randomized controlled trial

Abstract The aim of this double‐blind clinical trial was to investigate the effects of Nigella sativa oil on serum inflammatory and oxidative stress biomarkers and quality of life in patients with knee osteoarthritis (OA). Forty‐five patients who met the eligibility criteria were randomly divided into three groups with a ratio of 1:1:1. The first group received 2.5 mL oral N. sativa oil twice/day plus placebo topical oil, the second group received 2.5 mL topical N. sativa oil three times/day plus placebo oral oil, and the third group received oral and topical oil placebos. There were no intergroup differences in baseline characteristics. After 6 weeks of supplementation, oral N. sativa caused a significant improvement in the serum levels of hs‐CRP ( p = .003), MDA ( p = .003), and TAC ( p = .001). Oral N. sativa oil compared to placebo (aMD (95% CI): −0.81 (−1.45 to −0.19); p = .012) and topical N. sativa oil [aMD (95% CI): −0.76 (−1.38 to −0.15); p = .016] significantly reduced hs‐CRP serum levels. Significant improvements were observed in the general, physical, and mental health subscales in the oral and topical N. sativa oil compared to the placebo group ( p < .05). The six‐week oral N. sativa oil supplementation was effective in improving inflammatory biomarkers in knee OA. Both oral and topical N. sativa oil increased the quality of life.