Asthma is an incurable condition caused by chronic inflammation in the lungs. The goal of treatment is to control or reduce the severity of exacerbations. Black cumin (Nigella sativa, Ranunculaceae) seeds have anti-inflammatory, immunomodulatory, and antioxidant effects. Initial studies indicate that black cumin may be beneficial for patients with asthma; however, these studies had weak designs. The purpose of this single-blind, randomized, placebo-controlled study was to evaluate the effects of black cumin on clinical outcome measures and indicators of airway inflammation and airway constriction in patients with partly controlled asthma.
Patients (n = 76, age 18-65 years) with asthma according to the criteria of the National Institutes of Health were recruited from the pulmonary outpatient clinic of the University of Dammam, Saudi Arabia. Included patients had partly controlled asthma according to Global Initiative for Asthma guidelines, were nonsmokers, and had treatment for ≥ 3 months with daily maintenance therapy with inhaled corticosteroids without any concomitant asthma medications except for short-acting β-agonists. Excluded patients used additional asthma medications (e.g., leukotriene modifiers or oral steroids), had a severe exacerbation or hospitalization for asthma within 1 month prior to or during the study period, had chronic diseases, had compliance < 90% of the assigned medication, or were pregnant or lactating. Inclusion/exclusion criteria were confirmed after a 1-week run-in phase.
Patients were randomly assigned to receive placebo (520 mg charcoal powder; Arkopharma Pharmaceutical Laboratories; Carros, France) or 1 g or 2 g black cumin ground seeds taken as either one 500-mg capsule twice daily or two 500-mg capsules twice daily [Bio Extracts (Pvt) Ltd; Colombo, Sri Lanka] for 12 weeks. Patients were also required to continue with their regular maintenance inhaler therapy. Most patients were using budesonide [spelled incorrectly in the original article] 400 mcg daily and the remainder, fluticasone propionate 250 mcg twice daily. Control of asthma symptoms was assessed at 6 weeks and 12 weeks with (1) Asthma Control Test (ACT) to collect information about daytime and nocturnal symptoms, activity limitations, rescue inhaler use/need, exacerbation frequency, and baseline lung function; (2) recording of moderate or severe exacerbations as defined by the American Thoracic Society and European Respiratory Society criteria; (3) spirometry to measure forced expiratory volume at one second (FEV1% predicted), forced vital capacity, and forced expiratory flow (FEF25-75%); (4) peak expiratory flow (PEF) measured 2x/day at home before medicine was taken; (5) measurement of fractional exhaled nitric oxide (FeNO); and (6) blood drawn to measure total immunoglobulin E (IgE) and cytokines (interleukin [IL]-4, IL-10, IL-17, interferon-gamma [IFN-γ], and eotaxin).
At baseline, all 3 groups were similar in pulmonary function tests and all measured parameters. Treatment with placebo had no significant effect on any measured parameter. At 12 weeks, both black cumin groups had significant increases in the cytokine IFN-γ (P = 0.05 for both). There were no significant changes in any other cytokine measured. Compared with baseline, 1 g black cumin significantly reduced FeNO at 12 weeks (P < 0.05). Compared with baseline, 2 g black cumin significantly reduced IgE at 12 weeks (P < 0.01). Both black cumin groups had significantly higher ACT scores compared with baseline and compared with placebo at 6 weeks and 12 weeks (P < 0.001 and P < 0.01, respectively). For pulmonary function tests, FEV1% predicted and FEF25-75% were significantly improved compared with baseline in patients treated with 2 g black cumin for 6 and 12 weeks (P < 0.05 and P < 0.01, respectively). FEF25-75% predicted was significantly improved compared with baseline in patients treated with 2 g black cumin for 6 weeks (P < 0.01). Compared with placebo, both black cumin groups had significant improvement in PEF variability at 6 and 12 weeks (P < 0.05). Black cumin was well tolerated and no adverse effects were reported.
The authors conclude that adding black cumin to regular maintenance inhaler therapy improves overall control and decreases exacerbations in patients with partly controlled asthma. The authors state that this is the first study to demonstrate that black cumin can decrease FeNO, a marker of inflammation underlying the pathogenesis of asthma, in patients with asthma. However, the effect was observed only with the 1-g dose. The authors do not hypothesize why the 2-g dose did not have the same effect. The improvements in function as measured with the ACT correspond with the improvements in FeNO. IFN-γ is known to suppress inflammation in asthma, and in this study, there was a significant increase in IFN-γ with both doses of black cumin. Prolonged inflammation can result in remodeling of lung tissue, and the authors point out that black cumin may help reduce the severity of remodeling. The authors hypothesize that black cumin may be working by reducing pulmonary inflammation, which may ultimately prevent progression of bronchial remodeling. The authors were unable to receive consent for obtaining bronchoalveolar lavage or induced sputum samples to measure inflammatory cells. One of the advantages of the study was the excellent and robust randomization scheme. One limitation of this study was that it was single-blind rather than double-blind—the patients were blinded but not the researchers. This could have introduced bias into the data. The authors report no conflict of interest.
Salem AM, Bamosa AO, Qutub HO, et al. Effect of Nigella sativa supplementation on lung function and inflammatory mediators in partly controlled asthma: a randomized controlled trial. Ann Saudi Med. 2017;37(1):64-71.