Effects of a Diet Based on Inulin-rich Vegetables on Gut Health and Nutritional Behaviour in Healthy Humans

Study Overview
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Brief Summary
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Inulin-type fructans (ITF) are fermentable dietary fibres that can confer beneficial health effects through changes in the gut microbiota. However, their effect on gut sensitivity and nutritional behaviour is a matter of debate. The investigators evaluated, in healthy individuals, the impact of shifting from their usual food habits towards a diet based on the daily consumption of ITF-rich vegetables on gut microbiota, gastro-intestinal symptoms and food-related behaviour.

Official Title
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Modification of the Gut Microbiota Following the Consumption of Inulin-rich Vegetables: Effect on Gut Tolerance, Transit, Behaviour and Digestion in Healthy Humans

Conditions
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Healthy

Intervention / Treatment
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* Other: Diet based on inulin-rich vegetables


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI between 20 and 25 kg/m² Caucasian ethnicity Hydrogen producers (assessed by hydrogen breath test) Exclusion Criteria: Smokers Laxative consumption (<4 weeks) Severe intestinal problems Psychiatric problems or use of antipsychotic Consumption of antibiotics, pro/prebiotics, fibre dietary supplement, or any molecules that modifies the intestinal transit (<6 weeks) Specific dietary practise (vegetarian, vegan,...) Specific dietary treatment (<6 weeks) (e.g. high protein diet) Excessive alcohol consumption (>3 glasses/day) Consumption of the following drugs: proton pump inhibitor, antidiabetic drugs, cholesterol lowering drugs Inconclusive acceptability test (regarding the protocol of the intervention and the vegetables used in the protocol)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Dietary intervention<br> | Other: Diet based on inulin-rich vegetables<br>* During two weeks, healthy subjects were instructed to adhere to a controlled diet based on ITF-rich vegetables (±15 g ITF/day).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gut microbiota composition | Gut microbiota composition is assessed by 16S rRNA pyrosequencing. This analysis allows to obtain the relative abundance (%) of the different bacterial taxa and OTUs (operational taxonomic units). | 33 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gut microbiota fermentation in vivo | Gut microbiota fermentation is assessed in vivo by an hydrogen breath test. After an oral load of purified inulin, the level of expired hydrogen (ppm) is measured. | 33 days | 
| Gut microbiota fermentation in vitro | Gut microbiota fermentation is assessed in vitro by the measurement of total gas (ml/g of dry matter) produced from subject feces incubated with inulin-rich substrates. | 14 days | 
| Gastrointestinal Symptoms | Gastrointestinal symptoms were assessed by Visual Analogue Scale (horizontal line of 100 mm). Each subject completed seven separate scales, one for each symptom (rumble, burp, bloating, discomfort, nausea, flatulence, cramp), ranging from no sensation (0 mm) to very severe sensation (100 mm). | 33 days | 
| Appetite-related feelings | Appetite-related feelings were assessed by Visual Analogue Scale (horizontal line of 100 mm). Each subject completed seven separate scales, one for each appetite-related feeling (satiety, intention to eat, fullness, sweet envy, very sweet envy, fat envy, salt envy), ranging from no sensation (0 mm or 100 mm depending on the feeling) , to very strong sensation (0 mm or 100 mm depending on the feeling). | 33 days | 
| Correlation of gastrointestinal symptoms with gut bacteria | The levels of gastrointestinal symptoms were correlated (Spearman correlations) with the relative abundance of bacterial taxa and OTUs (operational taxonomic units) | 33 days | 
| Short chain fatty acids production | Short chain fatty acids (SCFAs) production was assessed in vitro by the measurement of total SCFAs (mg/g of dry matter) produced from subject feces incubated with inulin-rich substrates. | 14 days |