More than 7.4 million people in the UK are currently waiting for surgery. Behind that number are real people-patients preparing mentally and physically for procedures ranging from joint replacements to major heart and abdominal operations.

This research forms part of a broader strategy known as prehabilitation - preparing the body before surgery to improve outcomes afterward. For patients waiting for surgery, it represents a shift from passive waiting to active preparation.

Heart surgery for bypass or valve replacements results in inevitable yet controlled trauma. It increases inflammation, stress hormones and immune system demand. The body then has to repair itself - quickly and efficiently. And here's the surprising part. Inside your gut live trillions of bacteria - called your gut microbiome. These bacteria help regulate inflammation, strengthen your immune system and protect against infection.

This randomised clinical trial is investigating a fascinating question:

Can improving your gut microbiome through consumption of fibre before surgery help you recover faster, reduce time in ICU, shorten hospital stays, and lower complication rates? The placebo controlled trial will randomise 80 patients following eligibiilty checks to either 5g of prebiotic fibre/300mg of magnesium (WellBiome) OR 5g of maltodextrin for a period of 6-8 weeks prior to surgery. Patient will provide blood, urine and faecal samples at baseline and upon admission for surgery, and two further blood samples at day 3 and 6 post operatively.

Following surgery, patient outcomes will be assessed and compared between the experimental group (prebiotic fibre/magnesium) and placebo group (maltodextrin). The investigators are focussing on the time spent in the intensive care unit, complications and overall hospital stay. By documenting and quantifying these the investigators can calculate the costs and any savings between the groups.

INCLUSION CRITERIA:

• Aged 50-80
• BMI ≥ 25-40kg/m²
• Waist circumference >94cm (men) and 88cm (women)
• HbA1c 42-58 mmol/mol (6.0-7.5 old HbA1c units)
• No known intolerances to oligosaccharides and xylooligosaccharides
• Be stable dose of cholesterol and blood pressure medication for 3 months
• Be willing to participate and sign to that effect.

EXCLUSION CRITERIA

• Active cancer
• Any gastro-intestinal surgery or currently under the care of the GI clinical team for any clinically significant digestive issue (Crohn's, IBS, ulcerative colitis).
• On or had antibiotic treatment in the last 3 months.
• Patients who have taken ibuprofen in the last week or any condition that increases the likelihood of regular or sustained use during the intervention.
• On proton pump inhibitors (Omeprazole, Esomeprazole, Lansoprazole, Rabeprazole, Pantoprazole) within the last one month on long acting non-steroidal anti-inflammatory drugs in the last month or any condition that increases the likelihood of regular use during the intervention.
• Taking any prebiotic or probiotic supplementation within the last three months
• Patients who are vegetarians or vegans

We will share the clinical study report and derived data with researchers who provide a methodologically sound proposal and whose proposed use of the data has been approved by the study steering committee.

Starting 6 months following publication and ending 5 years after publication.

Researchers who provide a methodologically sound proposal and whose proposed use of the data has been approved by the study steering committee.