Combining Fasting and Fibre Interventions to Optimise Their Gut Microbiome-mediated Health Benefits

Combining Fasting and Fibre Interventions to Optimise Their Gut Microbiome-mediated Health Benefits

This study builds on the knowledge that fasting provides metabolic health benefits and that prebiotic interventions can enhance the gut microbiome's metabolic output to likewise improve host health. Whether long-term fasting and dietary fibre interventions could be combined to achieve synergistic improvements in host metabolic health is however unknown. The goal is to provide a proof of concept in a human trial that supplementing 10±4 days fasting with dietary fibre synergistically improves metabolic outcomes via gut microbiome-mediated effects. To assess this, we aim to analyse gut microbiome changes, functional outputs, and key metabolic markers such as butyrate production, glycaemic control and ketosis.

The randomised controlled trial includes 75 participants and has two arms: one involving fasting with fibre supplementation (n = 50) and one involving fasting without fibre supplementation (n = 25). All participants will undergo a fasting period of 10±4 days according to the Buchinger Wilhelmi protocol, followed by a stepwise reintroduction of food of up to 4 days. As dietary fibre we will use maize-derived resistant starch type IV, selected based on its ability to stimulate beneficial gut microbes like Oscillibacter and corn starch as placebo. Two main visits will be conducted: before and at the end of the fasting period. During these visits, blood and stool samples will be collected, and questionnaires will be completed. Additionally, daily measurements of anthropometric parameters and well-being will be recorded. Stool samples will also be collected one month afterwards as a follow-up. Participants' metabolic health will be evaluated through various clinical parameters (e.g., body measurements, blood pressure, glycaemic control, ketones, well-being). Additionally, multi-omics data, including metagenomics and metabolomics, will provide insight into the composition of the microbiome, as well as its outputs and functions. Furthermore, the effects of fasting on extracellular vesicles in blood will be explored.

Inclusion Criteria:

• Men and women
• Age: 18-65 years old
• Fasting for 10±4 days at the Buchinger Wilhelmi clinic in Überlingen
• BMI ≥ 25 kg/m²
• Signed informed consent

Exclusion Criteria:

• intake of antibiotics up to 2 months prior the study
• regular intake of pre-, post- and probiotics up to 2 months prior the study
• diagnosed Crohn's disease, Ulcerative colitis, IBD, coeliac disease
• medicated high blood pressure
• diagnosed diabetes mellitus type I
• medicated diabetes mellitus type II
• diagnosed kidney stone
• active malignant disease
• known substance addiction
• pregnancy or breastfeeding
• diagnosed with cachexia, anorexia nervosa, advanced kidney, liver or cerebrovascular insufficiency
• inability to sign the informed consent
• participation in another study