Synergistic Effects of Nigella sativa and Exercise on Diabetic Profiles: A Systematic Review

Individually, Nigella sativa (NS) and physical training interventions have been shown to be effective preventive and therapeutic strategies for diabetes mellitus. However, the effect of these in combination on bioindicators of diabetes has not yet been evaluated; there is little information available in the literature. A systematic review was therefore performed to assess any mutually potentiating impacts of NS and physical training interventions in diabetic subjects. A search was performed on this topic in the PubMed, CINAHL, Google Scholar and Web of Science databases for randomised, quasi-randomised or non-randomised controlled trials, studies with factorial or single-cohort pre-post designs, case series as well as case reports. The search terms encompassed various combinations of the following: "exercise", "training", "physical activity", "NS", "treadmill", "swimming", "Thymoquinone", "Nigellone", "caraway oil" and "black seeds". Two reviewers screened the abstracts of 202 identified publications according to predetermined inclusion criteria-i.e. papers published from 2009 onwards in the English language, studies on human or animal subjects, and the assessment of diabetic bioindicators following the combined administration of NS and exercise regimens in comparison with just one of these interventions or against controls. Despite the rich data available regarding the effect of both interventions separately, two human studies and two animal studies were ultimately included in the review. However, the benefit of combined administration of NS and exercise regimens on glycemic and lipidemic control was much more obvious compared to exercise alone. In conclusion, these findings suggested that combined administration of NS and exercise regimens could be used as an effective adjuvant for oral antidiabetic drugs in diabetes control.