Volume 49, November 2022, 101666AbstractBackground and purpose

The oil of Nigella sativa (NS) seeds has analgesic and anti-inflammatory effects. Therefore, the efficacy and safety of NS oil in the treatment of knee osteoarthritis were evaluated.

Materials and methods

One hundred and sixteen patients aged 50–70 years were randomly assigned to take 2.5 mL NS oil (N = 58) or placebo (N = 58) orally every 8 h for 1 month. WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) was the primary outcome measure and Visual Analog Scale (VAS) for pain, number of 500 mg acetaminophen tablets taken per day during the trial, patients’ satisfaction with the interventions, complete blood count and the blood levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine and blood urea nitrogen were the secondary outcome measures.

Results

Fifty two and 54 patients respectively in the NS oil and placebo groups completed the study. The VAS scores were decreased by 33.96 ± 17.04% (NS oil group) and 9.21 ± 0.32% (placebo group) (p < 0.001), and WOMAC total scores were decreased by 27.72 ± 18.61% (NS oil group) and 1.34 ± 2.31% (placebo group) (p < 0.001) compared to baseline. The NS oil reduced the dose of acetaminophen significantly compared with the placebo (p = 0.001). The patients were significantly more satisfied with the NS oil than the placebo (p < 0.001). The NS oil had no significant effect on the other variables. There was no side effect.

Conclusion

Oral NS oil safely reduces the osteoarthritis symptoms and analgesic dose in the knee osteoarthritis patients.

Section snippetsAuthor contribution statement

Hasan Fallah Huseini: Conceptualization, Methodology, Software, Funding acquisition; Reza Mohtashami: Data curation, Project administration; Elaheh Sadeghzadeh: Visualization, Investigation; Soraya Shadmanfar: Resources, Supervision, Validation; Fataneh Hashem-Dabaghian: Formal analysis; Saeed Kianbakht: Writing- Reviewing and Editing.

Trial design

This study was a two-arm, randomized, double-blind, placebo-controlled and parallel-group trial.

Participants

This trial was conducted in the Baqiyatallah hospital (Tehran, Iran) from 2018 to 04–20 to 2019-12-22. Inclusion criteria were Iranian males or females aged 50–70 years diagnosed with primary knee osteoarthritis using the criteria of the American College of Rheumatology, grade 1 or 2 of osteoarthritis according to the Kellgren-Lawrence criteria, WOMAC (Western Ontario and McMaster Universities

Quantitative analysis of thymoquinone

The concentration of thymoquinone in the NS oil was 0.97 ± 0.05 mg/mL (Fig. 1, Fig. 2, Fig. 3).

Fatty acid analysis

Linoleic acid (49.37%), palmitic acid (20.27%), oleic acid (5.76%), stearic acid (5.48%), palmitoleic acid (0.94%), arachidic acid (0.90%) and myristic acid (0.63%) were the main fatty acids of the NS oil. Polyunsaturated fatty acids, saturated fatty acids and monounsaturated fatty acids constituted respectively 58.59%, 28.04% and 6.70% of the NS oil.

Clinical trial

The CONSORT flow diagram of the trial is shown in

Discussion

The purpose of this trial was to evaluate the efficacy and safety of the oral intake of NS oil for the symptomatic treatment of the knee osteoarthritis patients. As regards the results, two measures of pain, i.e. VAS and WOMAC corroborated analgesic action of the oral NS oil in the knee osteoarthritis. Further, the NS oil decreased WOMAC stiffness score more than WOMAC pain and function scores. While the patients of this study had mild radiographic knee osteoarthritis according to the

Conclusion

The results suggest that oral intake of 2.5 mL of the NS oil every 8 h is safe and decreases the symptoms and analgesic dose in the knee osteoarthritis patients. Studies ascertaining the NS oil's mechanisms of action, bioactive compounds, and effects on joint space narrowing in osteoarthritis are recommended.

Declaration of competing interest

None.

Acknowledgement

This study was taken from the dissertation of Dr. Elaheh Sadeghzadeh for the degree of internal medicine specialist and funded by the Institute of Medicinal Plants (Karaj, Iran) affiliated with the Academic Center for Education, Culture and Research, and the Baqiyatallah University of Medical Sciences (Tehran, Iran).

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