Dietary carbohydrate intake and health-related outcomes: a protocol for the evidence evaluation methodology for the new guideline on dietary carbohydrate intake of the German nutrition society.

Abstract

This protocol outlines the rigorous process for developing the new German guideline on dietary carbohydrate intake and its impact on health-related outcomes, building on a substantial body of evidence regarding carbohydrate quantity and quality. A professional guideline panel has been established, and research questions have been formulated a-priori. The novel methodological approach follows a structured process and adheres to established recommendations for guidelines. Umbrella reviews of systematic reviews with meta-analyses of randomized controlled trials or prospective observational studies on carbohydrate quantity and quality in relation to health-related outcomes will be conducted. Relevant aspects of carbohydrate intake include total carbohydrates, dietary sugars, starch, the dietary glycaemic index, the dietary insulin index, dietary glycaemic load, dietary insulin load, dietary fibre, and whole grains. The prioritized outcomes include body weight-related outcomes, type 2 diabetes, dyslipidemia, elevated blood pressure, cardiovascular diseases, cancer, and dental caries and periodontal diseases. The literature search will be conducted in MEDLINE and Epistemonikos starting from 2015, as older reports are likely covered or superseded by more recent ones. The most comprehensive systematic review with meta-analysis with the highest methodological quality standards (according to a modified version of AMSTAR 2) will be selected for each specific association or effect. The certainty of evidence will be rated using the GRADE approach. The guideline development will follow the Evidence-to-Decision (EtD) framework. This methodological protocol is in line with international standards and provides transparent framework for the guideline on dietary carbohydrate intake and health-related outcomes of the Germany Nutrition Society.