Ginger for health care: An overview of systematic reviews

Objectives: To summarize the evidence from systematic reviews (SRs) and meta-analyses that evaluated the efficacy of ginger in treating any conditions and critically assess the quality of these evidence. Methods: A systematic search of the literature was conducted from inception until February 28, 2019 using the PubMed, EMBASE, Web of science, Cochrane library, and four Chinese databases. Literature selection and data extraction were conducted by two independent reviewers. The quality of SRs was evaluated using the AMSTAR-2 tool. The GRADE system was used to assess the quality of evidence. Results: Twenty-seven SRs were included. The number of included studies were various, range from 3 to 27. The condition with the most included SRs was nausea and vomiting (n = 12, 44.4%). Many SRs showed a promising efficacy of ginger, including nausea and vomiting, metabolic syndrome and pain, while the effect of ginger for platelet aggregation failed to draw a certain conclusion. The quality of SRs was heterogeneous. All of included SRs well complied with the Item 1 (research questions included the components of PICO) and Item 3 (explained selection of the study designs for inclusion). Twenty review failed to provide registration information. Only one SR reported the sources of funding for studies included. Conclusions: In our overview, most of SRs suggest ginger is a promising herbal medicine for health care, which is beneficial for nausea and vomiting, metabolic syndrome and pain. However, considering the limited quality of included evidence and heterogeneity of different clinical trials, more well-design studies are required to confirm the conclusion further.