METADIS: CARBHEALTH Carbohydrate staple foods - facing the challenge to improve their quality for a better metabolic health

After the start of the project in April 2020, and the implications of lockdown and the pandemic, we were finally able to start with our multicenter clinical trial, the bread- exchange study. For this study, our project partner Nofima AS had produced to different breads. These breads were also then investigated in a study to determine their glycemic index. Now, the clinical study is ongoing at all project sides and has even be finished at one side in Germany. Recruitment of participants runs smoothly and we expect to report the results during 2023. The protocol of the clinical trial was published in the journal 'BMJ Open' in 2022 Further, we have conducted a systematic review which investigated the glycemic response to different types of bread in published articles. This study was accepted by the journal 'Advances in Nutrition', which is a high-ranked journal within nutrition science. It is expected that the article is published by the end of 2022. Data from the HUSK2 study on whole grain intake, bread intake and the biomarker alkylresorsinols are currently being analysed for their association with the metabolic syndrome. The metabolic syndrome is a condition of obesity combined with either dyslipidemia, hyperglycemia and hypertension which was present in about 1/3 of the participants in HUSK2. The metabolic syndrome is associated with increased risk of cardiovascular disease and diabetes mellitus. We expect the results and a scientific publication during the first part of 2023. We still have digital meetings with all the project partners. However, we were able to have one in person meeting with all partners in May 2022 in Bergen. Also, we presented first results at international conferences, which are still mostly digital.

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Carbohydrates are the main energy source in most European diets. Their metabolic effects depend on several aspects ranging from chemical structure to food processing which is best captured by the combined consideration of dietary fiber, whole grain, glycemic index, and dietary sugar. In Northern and Central European diets, bread is a major carbohydrate source, however, beneficial metabolic effects of bread may be confined to bread with a low glycemic index (GI) only. The 5 partners from Norway, Germany, and Sweden in this consortium will run a 16-week RCT involving 250 persons at risk of type 2 diabetes (T2DM) to test a newly developed bread containing the oat-derived fiber beta-glucan characterized by a comparably low GI of 57 for its effects on glycemic control. A conventional high-fiber bread without beta-glucan and a high GI (>70) will serve as a comparator. Secondary outcomes include body weight and composition, serum lipids and hepatic steatosis index as well as gastric emptying, satiety and postprandial glycemic response in subgroups. Furthermore, the long-term relevance of bread intake and carbohydrate quality for body weight and T2DM or glycemic control will be analyzed in existing observational cohorts involving middle-aged healthy adults (HUSK study, Norway) and in lean and obese children followed-up until adulthood (KFO and Life child, Germany). Alkylresorcinols, established biomarkers of whole-grain consumption will be measured in plasma samples of the cohorts and will supplement self-reported dietary data. Finally, RCTs and observational studies on the relevance of bread consumption for body weight, glycemic control/T2DM, and associated cardiometabolic outcomes will be summarized in systematic reviews and meta-analyses. Taken together this project will address the overall hypothesis that habitual consumption of a high fiber bread can form an integral part of a plant-based healthy diet associated with benefits for body weight and T2DM risk.