The effect of Nigella Sativa on Cardiometabolic Outcomes: A Systematic Review and Meta-Analysis of C

Abstract

Objective: Nigella Sativa, commonly known as Blackseed, has been mentioned in the Hadith as a cure for all diseases except death. In the past Black seed has been used as a treatment for a number of medical conditions including infections and headaches. Recently studies have been performed to evaluate the medicinal properties and therapeutic potential of Blackseed. We conducted a systematic review and meta-analysis of controlled trials to assess the effect of Blackseed on cardiometabolic outcomes.Methods: MEDLINE, EMBASE, and The Cochrane library were searched through September 2017. Randomized and non- randomized controlled trials of ≥1-week duration that assessed cardiometabolic risk factors in participants from all health backgrounds were included. Two independent reviewers extracted relevant data and assessed risk of bias (Cochrane Risk of Bias tool). Data was pooled using random effects inverse variance method and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Heterogeneity was assessed (Cochran Q) and quantified (I2 statistic).Results: We included 15 trials (n=1,010, median length = 8 weeks). The blackseed dose ranged from 150mg to 2g/day or 2.5ml to 5ml/day. Regular blackseed intake reduced systolic blood pressure (MD= -7.59 mmHg [95% CI, -10.61, -3.45]), diastolic blood pressure DBP (MD=-3.49 mmHg [95% CIs, -5.67, -1.30]), LDL-Cholesterol (MD=–4.40 mmol/L [95% CIs, -5.83, -2.98]) and increased triglycerides (MD=6.48 mmol/L [95% CIs, 2.65, 10.31]) but it had not effect HDL-cholesterol. Regular blackseed intake had no effect (p>0.05) on glycemic markers (fasting blood glucose, HbA1c), liver enzymes (AST, ALT and GGT), inflammatory and renal markers (uric acid, blood urea nitrogen), or adiposity (weight, weight circumference, BMI). Conclusion: Pooled analyses show a modest beneficial effect of blackseed intake on blood pressure, and a varying effect on lipid markers. There is a need for larger, longer and higher quality trials, as our confidence in the results is low.