Background of the study:

Protein intake is often higher than recommended in Western countries. This leads to increased amounts of protein flowing into the large intestine. Next to increased dietary protein intake, protein digestibility, and endogenous protein losses also affect the amount of protein entering the large intestine. However, these aspects have barely been studied, especially in humans. The large intestine is home to the largest bacterial ecosystem of the body. During the fermentation of protein by these bacteria (microbiota), metabolites are produced such as ammonia, branched-chain fatty acids, biogenic amines, phenolic compounds, indoles, and N-nitroso compounds. There is evidence that some of these metabolites could be harmful for gut epithelia, gastrointestinal health, and health in general after they enter blood circulation. In general, doing measurements inside the gastrointestinal tract is invasive. During this project the protein fermentation will be studied in the gastrointestinal tract using feces and urine, but also in situ using the GISMO GEN1 ingestible. This ingestible contains sensors to measure pH, ammonium, temperature, and redox potential.

Objective of the study:

The primary objectives of this study are:

1. To investigate the feasibility of the GISMO GEN1 System to monitor biomarkers in the gastrointestinal tract by studying the ingestible transit time, data coverage, participant experience, and serious adverse events (if applicable).
2. To study the effect of a 7-day high versus low digestible protein source present in the diet on protein fermentation in healthy subjects, measured by ammonia concentrations.

Study design:

The study is divided into 2 phases. In phase 1, preliminary feasibility of the GISMO GEN1 ingestible system will be assessed and the baseline measurements will be taken without any dietary restrictions. An interim analysis will be performed after phase 1 and only after a positive evaluation of the GISMO GEN1 System, the study will continue with phase 2.

Phase 2 is a randomized cross-over controlled feeding trial. Two diets will be used: one diet containing a high digestible protein source, and the other diet containing a low digestible protein source. Each diet will be given for 7 days, with a wash-out period in between. Measurements done during the dietary interventions will be compared to the other diet, and to the baseline measurements.

Study population:

15 healthy male or female volunteers, age 16 or older, BMI 18.5-30.

Intervention:

A high digestible protein diet (30 g/d whey protein) and a low digestible protein diet (30 g/d bovine plasma protein).

Primary study parameters/outcome of the study:

Ammonia as biomarker for protein fermentation, measured in feces and urine and in situ by the GISMO GEN1 ingestible.

Also, ingestible transit time, data coverage, participant experience, and serious adverse events.

Secundary study parameters/outcome of the study (if applicable):

Secondary study parameters include other protein fermentation related metabolites measured in feces, urine and blood; microbiome composition; transit time; absorption kinetics.

Inclusion Criteria:

• Males and females
• Age between 16 years or older
• BMI between 18.5-30 kg/m2
• Normal bowel movement: at least one defecation per 48 hours
• Suitable veins for insertion of cannula

Exclusion Criteria:

• Having a current or past medical history or surgical events that may either put the subject as risk because of participation in the study, or influence the results of the study, including, a swallowing disorder, gastrointestinal or liver or endocrine or renal or cardiovascular disease, any other chronic disease, partial bowel resection, renal failure, cancer, nose/throat diseases, gastric bypass surgery, use of anticoagulants; as determined by the medical supervisor;
• Use of any medications in the week before the study that could substantially alter gastrointestinal motor function (e.g., opioids, prokinetics, anticholinergics, laxatives), or acidity (PPI, H2RA), as determined by medical supervisor;
• Having a bleeding/coagulation disorder, including hemophilia, Von Willebrand disease, Bernard-Soulier, Glanzmann thrombasthenia or thrombocytopenia;
• Swallowing disorders; Among others: dysphagia, any oropharyngeal or oesophageal stricture, functional abnormality, or anxiety disorders related to swallowing disorders;
• Severe dysphagia to food or pills;
• Suspected or known strictures, fistulas, or physiological/mechanical GI obstruction;
• Previous GI abdominal surgery; Except: uncomplicated appendectomy, and/or laparoscopic cholecystectomy;
• Pregnancy, recent childbirth in last 6 months, or actively trying to get pregnant;
• Planned MRI procedure during the study;
• Pacemakers, defibrillator, infusion pump, or other implanted electromedical devices;
• Suffering >2 times per week from: nausea / vomiting / decreased appetite / abdominal pain / high blood pressure / headaches, shakiness, and weakness / fever / diarrhea / constipation;
• Unwilling to undergo an X-ray examination and/or ultrasound (in case sensorcapsule exit cannot be confirmed);
• Working in a professional healthcare facility (e.g. hospital, dental office, emergency room), military area (e.g. submarine, near radar installation), or heavy industrial area (e.g. power plants, automotive, mining, refineries) during the duration of the study;
• Having an allergy or intolerance towards compounds in the prescribed foods (e.g. gluten, lactose, fish, peanuts, soy, nuts);
• Following a vegetarian or vegan diet;
• Use of prebiotic supplements or probiotics for 3 months before the start of the study;
• Use of antibiotics within 2 months of starting the study or planned during the study;
• Excessive alcohol consumption (alcohol: <21 consumptions/week for men, and <14 consumptions/week for women);
• Use of soft drugs within 1 month of starting the study or during the study;
• Use of hard drugs;
• Hemoglobin levels <8.5 mmol/L for men and <7.5 mmol/L for women;
• Participation in another biomedical study;
• Not having a GP;
• Being an employee of Wageningen University, Division of Human Nutrition and Health.

Participants are masked regarding the protein source in the dietary intervention. Participants are not masked regarding the ingestible.