The effect of Nigella sativa on oxidative stress and inflammatory biomarkers: a systematic review and meta-analysis

Abstract

ObjectivesThe present systematic review of literature was conducted to study the effect of Nigella sativa (N.S) on oxidative stress and inflammatory biomarkers.ContentDifferent online databases such as Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), Scopus, Web of Sciences, EMBASE, and Clininaltrial.gov for English articles and national databases of SID, Magiran, Irandoc, and Iranmedex for Persian articles, which were published until March; 2019 were scrutinized. All Randomised Controlled Trials (RCTs) and quasi-experimental studies that aimed to compare the impact of N.S along, with placebo or without supplementation, on inflammatory factors and oxidative stress were entered in the present study.SummaryFinally, 11 RCTs covering 710 women and men, in total, were participated in the present meta-analysis. Significant differences were observed in Tumor Necrosis Factor alpha (TNF-α) (Weighted Mean Difference (WMD) =−2.15 pg/mL, 95% Confidence Interval (CI) =−3.22–−1.09, I2=32%; 5 trials with 262 participants) superoxide dismutase (WMD=63.79 µ/gHb, 95% CI=6.84–120.75, I2=0%; 2 trials, with 88 participants), and total antioxidant capacity (WMD=0.34 mmol/L, 95% CI=0.04 to 0.63, I2=94%; 5 trials with 232 participants). Nevertheless, there was no significant difference in high sensitivity C-reactive protein (WMD=−0.98 mg/L, 95% CI=−1.98–0.03, I2=78%; 5 trials with 267 participants), Interleukin 6 (IL-6) (WMD=−0.25 pg/mL, 95% CI=−0.65 to 0.16, I2=0%; 2 trials with 134 participants), and malondialdehyde (WMD=−0.95 nmol/mL, 95% CI=−1.97–0.08, I2=68%; 4 trials with 179 participants).OutlookGenerally speaking, N.S probably results in the improvement of superoxide dismutase serum levels, TNF-α, and total antioxidant capacity. Thus, further studies are required to fully assess its impacts on all oxidative stress and inflammatory biomarkers.

Nigella sativa and health outcomes: An overview of systematic reviews and meta-analyses

“…Subsequently, 210 records were excluded after screening titles and abstracts. The full texts of 34 records were further evaluated, and 20 records (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) were eventually included in the analysis (Figure 1 shows the flow chart of study selection).…”

“…All meta-analyses were published in peer-reviewed journals between 2016 and 2022. These studies were conducted in seven regions: 13 from Iran ( 28 , 30 , 33 , 34 , 37 – 45 ), two from China ( 32 , 35 ), and one each from Australia ( 26 ), India ( 27 ), United Kingdom ( 29 ), the USA ( 31 ), and Indonesia ( 36 ). The number of RCTs ranged from three to 50, with 187–3,679 subjects.…”

“…Four studies registered protocols on the PROSER platform ( 27 – 29 , 39 ) and one in the Cochrane library ( 31 ). In terms of the risk of bias tools, 10 studies used the Cochrane risk of bias tool ( 26 – 28 , 30 , 31 , 33 , 35 , 39 , 44 , 45 ), nine studies used the Jadad scale ( 32 , 34 , 36 – 38 , 40 – 43 ), and one used the standardized JBI critical appraisal checklist ( 29 ). Table 1 summarizes the basic characteristics of the included meta-analyses.…”

“…Most studies have reported forms of N. sativa, including capsules, oils, and powders. Nineteen studies reported doses of N. sativa, ranging from 0.5 to 6 g or 2.5 to 5 ml daily (26)(27)(28)(29)(30)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45). Five studies reported the frequency of N. sativa administration, which varied between once, twice, and thrice a day (29, [32][33][34][35].…”

“…In adults, studies have observed that N. sativa intake significantly reduced tumor necrosis factor-α (TNF-α) (26,33,34), high-sensitivity C-reactive protein (hs-CRP) (34,35), interleukin-6 (IL-6) (33), and C-reactive protein (CRP) (38,40). However, other meta-analyses have shown that N. sativa supplementation had no effect on TNF-α (37,38), hs-CRP (33), IL-6 (33), and CRP (37). In addition, one study observed that consumption N. sativa decreased interleukin-4 and increased interferon-γ in patients with asthma, but the difference was not statistically significant (32).…”