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

Condition(s) studied

Investigational drug(s) / intervention(s)

Fibre Arm: 10±4 days of fasting according to the Buchinger Wilhelmi fasting protocol, followed by a structured food reintroduction period, combined with 20 g/day of maize-derived resistant starch type IV.

Control Arm: 10±4 days of fasting according to the Buchinger Wilhelmi fasting protocol, followed by a structured food reintroduction period, combined with 1.2 g/day of corn starch placebo.

Study summary

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.

Eligibility

Primary outcome measure(s)

• Abundance of butyrate-producing gut bacteria — Baseline (T0) and end of the 10±4-day fasting period (T1)
  Change in the relative abundance of butyrate-producing gut bacteria assessed by metagenomic profiling of faecal samples.
• Change in fasting venous plasma glucose — Baseline (T0) and end of the 10±4-day fasting period (T1)
  Fasting venous plasma glucose concentration measured by clinical laboratory analysis (mmol/L).

Trial sites (1)

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