Associations between plant-based diets, plant foods and botanical supplements with gestational diabetes mellitus: a systematic review protocol

Introduction Gestational diabetes mellitus (GDM) is one of the most common health complications during pregnancy. Medical nutrition therapy is the mainstay of treatment for GDM, however, there is no current consensus on optimal dietary approaches to prevent or control hyperglycaemia in pregnancy. The aim of this systematic review is to assess the relationships between plant-based dietary patterns, plant foods and botanical dietary supplements with GDM and maternal glycaemic biomarkers.Methods and analysis A predefined search strategy was used on 16 June 2021, to search PubMed, Embase and CINAHL Plus with Full Text (EBSCOhost), as well as ClinicalTrials.gov, for studies published as original articles in English. Articles will be included if they are human observational studies or clinical trials and will be excluded if they are review articles or conference abstracts. We will use Cochrane’s risk of bias tools for interventions that are parallel arm (Risk of Bias tool for randomised trials version 2 (RoB 2)) and single arm, non-randomised intervention studies (Risk of Bias In Non-randomised Studies-of Interventions (ROBINS-I)). For observational, case–control and cross-sectional studies, we will use the National Heart, Lung and Blood Institute’s quality assessment tools. Data will be synthesised in a narrative format describing significant results as well as presenting the results of the quality assessment of studies.Ethics and dissemination This systematic review does not require ethical approval as primary data will not be collected. The review will be published in a peer-reviewed journal and disseminated electronically and in print.PROSPERO registration number CRD42022306915.