Skip to main content
OpenTrials
Recruiting

NCT Number: NCT07268508

Impact of a Pro-diversity Gut Microbiota Diet After a Bariatric Surgery on Gut Microbiota, Eating Behaviour and Sensory Function

Bariatric surgery is the most effective treatment for long-term weight loss and reducing obesity-related health risks. It alters the gastrointestinal tract as well as metabolic and hormonal functions, influencing eating behaviour. However, weight loss outcomes and long-term maintenance vary between patients, likely due to changes in the gut microbiota. Dietary recommendations aimed at improving microbiota diversity could help support sustained weight loss after surgery.

The BariaGut Taste study aims to compare two dietary approaches following bariatric surgery: nutritional counselling promoting gut microbiota diversity versus standard nutritional counselling. One year after surgery, the study will evaluate differences in microbiota diversity, changes in food preferences and eating behaviours, sensory profiles (taste, smell), levels of digestive and gut hormones fasting, before and after eating, cardiometabolic parameters, mental health, physical activity, and more, to better understand Bariatric surgery is the most effective treatment for long-term weight loss and reducing obesity-related health risks. It alters the gastrointestinal tract as well as metabolic and hormonal functions, influencing eating behaviour. However, weight loss outcomes and long-term maintenance vary between patients, likely due to changes in the gut microbiota. Dietary recommendations aimed at improving microbiota diversity could help support sustained weight loss after surgery.

The BariaGut Taste study aims to compare two dietary approaches following bariatric surgery: nutritional counselling promoting gut microbiota diversity versus standard nutritional counselling. One year after surgery, the study will evaluate differences in microbiota diversity, changes in food preferences and eating behaviours, sensory profiles (taste, smell), levels of digestive and gut hormones fasting, before and after eating, cardiometabolic parameters, mental health, physical activity, and more, to better understand the mechanisms that may explain variations in response to bariatric surgery.

The BariaGut Taste study is a prospective, randomized, controlled trial with two parallel groups, involving non-diabetic patients aged 25 to 65 y undergoing either sleeve gastrectomy or Roux-en-Y gastric bypass. The trial will be conducted at the digestive surgery department of Edouard Herriot Hospital, the endocrinology-diabetes-nutrition department of Lyon Sud Hospital Center, and the Human Nutrition Research Center Rhône-Alpes. 60 participants are expected to be recruited, with 30 in each arm.

Participants will be enrolled before surgery during a routine care visit with the surgeon. They will then undergo a metabolic assessment visit conducted exclusively for research purposes. This visit will allow to collect baseline data on primary outcomes via blood, expired air, and stool samples, anthropometric measurements, indirect calorimetry, a battery of questionnaires (TFEQ-21, DEBQ, PHQ-9, SF36, GSES, PANAS, ESUL, BES, DERS, GAD-7, IPAQ, BAQ, GSRS, sensory alterations, Bristol and Likert scales, and FNS), computerized food preference tests (LFPQ), and a standardized, video-recorded ad libitum buffet.

Participants will be followed up at 3, 6, and 12 months after surgery through visits combining clinical care and research assessments. The dietary interventions specific to each group will be provided since the 3-month visit. The assessments conducted before surgery will be repeated at 6 and 12 months, also integrating clinical care objectives.

Additional blood, stool, and adipose tissue samples collected during surgery will be stored to create a biobank.

Recruiting

Interested in participating?

Request Info

Key information

Age range

25 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Hospital Edouard Herriot, digestive surgery department, Lyon, France

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Between 25 and 65 years old
  • Undergoing either sleeve gastrectomy or Roux-en-Y gastric bypass
  • With grade 3 obesity (BMI≥40 kg/m²) or with BMI≥35 kg/m² and at least one comorbidity likely to be improved after surgery, with the exception of type 2 diabetes
  • Signed consent form
  • Living less than an hour and 30 minutes from the hospital
  • Presence of effective and stable contraception for women of childbearing potential

Exclusion criteria

  • Type 2 diabetes
  • Presence of a contraindication to bariatric surgery
  • Presence of gastrointestinal pathologies with an inflammatory component, known gastroparesis, total gastrectomy, colectomy, exocrine pancreatic insufficiency, known endocrine pathologies inducing hyperglycaemia (uncontrolled dysthyroidism, acromegaly, hypercorticism, etc.), severe chronic renal insufficiency (< 30mL/min), or hepatocellular insufficiency
  • Claustrophobic
  • Pregnant or breastfeeding women
  • Taking an obesity treatment 3 months before surgery
  • Taking a corticoids, immunosuppression, anabolizing, or growing hormones, antibody treatments less than 3 months before inclusion
  • Daily taking of laxatives or drugs that can strongly interfere with the composition of the intestinal microbiota. If taken sporadically, the patient can be included at a distance (3 weeks) from the laxatives taken.
  • Specific diets (vegetarian, vegan or without gluten)
  • No French speaker
  • Already included in other study
  • Donated blood in the last two months
  • Without freezer access
  • With allergy or intolerance to food propose in ad libitum buffet

Treatment and study plan

nutritional counseling

Other

Nutritional counseling

Primary outcomes

  1. Microbiota diversity 12 months after surgery

    Time frame: Primary outcome will be assessed three times : before the surgery, 6 and 12 months after

    The change in the diversity of the microbiota (shot gun metagenomic analysis, counting the number of microbial genes), between before surgery and one year after surgery (delta) between the two dietary intervention groups.

Secondary outcomes

  1. Eating behaviour during a standardised, filmed and validated ad libitum buffet : Food intake

    Time frame: Before the surgery and at 6 and 12 month after

    energy intake, macro- and micronutrient intake The items chosen during the buffet from the 17 items that will be offered will be noted. The quantities in g and calories consumed of each item will be estimated from the weighing of the plates before and after the buffet, the contribution of each of the items to the energy intake will also be evaluated.

  2. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Nutritional quality

    Time frame: Before the surgery and at 6 and 12 month after

    Nutritional quality through analysis of the foods chosen and consumed Buffet items are classified (pre-defined classification) into seven groups based on their macronutrient content and energy density: starchy foods, meat and fish, fruits and vegetables, dairy products, sweet desserts, sauces, and sweetened beverages. They are also classified according to their fat, sugar, and protein content, and their energy density (4 groups).

    The quantities consumed in grams and as a percentage of energy intake per group will be assessed for each subject and per visit.

  3. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    time spent selecting food at the buffet, duration of ingestion, ingestion speed, total meal duration, number of bites per minute, total number of bites and bites by food type, and food choices

    Several indicators will be assessed for the buffet's microstructure based on the analysis of videos taken during the buffet:

    • Buffet time
  4. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal appreciation

    Time frame: Before the surgery and at 6 and 12 month after

    time spent selecting food at the buffet, duration of ingestion, ingestion speed, total meal duration, number of bites per minute, total number of bites and bites by food type, and food choices Assessed with visual analog scale from 1(worse outcome) to 10 (better outcome)

  5. Eating behaviour and preferences : Behaviors

    Time frame: Before the surgery and at 6 and 12 month after

    binge eating using sub-scores from tthe BES (Binge Eating Scale) for binge eating

    BES : Binge Eating Scale - score from 0 to 46, score of 46 = highest level of binge eating disorder

  6. Eating behaviour and preferences : Food preferences

    Time frame: Before the surgery and at 6 and 12 month after

    Food preferences using the short version of the LFPQ (Leeds Food Preference Questionnaire) LFPQ : Leeds Food and Preference Questionnaire- score from 0 to 100 on preference or motivation for a type of food, high score = strong preference or motivation

  7. Appetite : hunger level

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : hunger

  8. Appetite : satiety

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated rom 0 (worse outcome) to 10 (better outcome) on the following dimensions : feeling of satiety

  9. Appetite : desire to eat

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : desire to eat

  10. Appetite : prospective consumption

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : consommation

  11. Appetite : meal appreciation

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated rom 0 (worse outcome) to 10 (better outcome) on the following dimensions : meal appreciation

  12. Sensory functions : detection scores

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Taste Strips tests

  13. Sensory functions : intensity

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Taste Strips tests

  14. Sensory functions : pleasantness

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Taste Strips tests

  15. Sensory functions : edibility of tastes

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Taste Strips tests

  16. Sensory functions : edibility of odors

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Taste Strips tests

  17. Self-reported alterations in sensory functions

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using dedicated questions

  18. Body perception

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using the BAQ questionnaire (Body Awareness Questionnaire) BAQ : Body Awarness Questionnaire - score from 13 to 65, score of 65 = positive assessment of one's body

  19. Appetite : desire to eat

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated from 0 to 10 on the following dimensions: desire to eat

  20. Appetite : prospective consumption

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using visual analog scales rated from 0 to 10 on the following dimensions

  21. Microbiota composition

    Time frame: Before the surgery and at 6 and 12 month after

    Evaluated via gene function analysis from metagenomics data, metabolomics and short-chain fatty acid quantification

  22. Microbiota function

    Time frame: Before the surgery and at 6 and 12 month after

    Evaluated via gene function analysis from metagenomics data, metabolomics and short-chain fatty acid quantification

  23. Endocrine, digestive or intestinal hormones

    Time frame: Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)

    Blood sample to measure :

    Adiponectin µg/ml

  24. Exhaled gas profiles

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed by volatolomic signatures

  25. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    BMI will be assessed

  26. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    Energy metabolism by indirect calorimetry

  27. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    postprandial plasma markers: We will assess: glycaemia (g/L)

  28. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    CRP

  29. Vital parameters

    Time frame: Before the surgery and at 6 and 12 month after

    Blood pressure

  30. Nutritional status: Blood vitamin

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Blood vitamin status :

    For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

    The vitamins assessed are :

    • Vitamin B12 (pmol/L) should be above 145 pmol/L
  31. Nutritional status : Blood mineral

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Blood mineral status:

    • Calcium (mmol/L) should be above 64 mmol/L
    • Phosphor (mmol/L) should be above 0.81 mmol/L
    • Magnesium (mmol/L) should be above 0.66 mmol/L
    • Sodium (mmol/L) should be above 136 mmol/L
    • Potassium (mmol/L) should be above 3.4 mmol/L
    • Chlore (mmol/L) should be above 98 mmol/L
  32. Nutritional status : Plasma fatty acid

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Plasma fatty acid profile

  33. Nutritional status : Protein

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Protein status

  34. Average energy

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits

  35. macronutrients intakes and proportions

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits

  36. micronutrients intakes and proportions

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits

  37. Mental health: Quality of life

    Time frame: Before the surgery and at 6 and 12 month after

    Quality of life using the SF36 questionnaire SF36 - health status questionnaire - score from 0 to 100, score of 100 = excellent perceived health

  38. Mental health: Self-confidence

    Time frame: Before the surgery and at 6 and 12 month after

    Self-confidence and self-efficacy using the GSES GSES: Generalized Self-Efficacy Scale - score of 10 to 40, score of 40 = strong confidence in one's ability to effectively manage different life situations and challenges

  39. Mental health: Depression

    Time frame: Before the surgery and at 6 and 12 month after

    Depression with PHQ-9 PHQ-9: Patient Health Questionnaire

    -score from 0 to 27, score of 27=severe depression

  40. Mental health: Anxiety

    Time frame: Before the surgery and at 6 and 12 month after

    Anxiety assessment using GAD-7 GAD-7: Generalized Anxiety Disorder - if score >7 then anxiety disorders should be suspected

  41. Physical activity

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using the short version of the IPAQ IPAQ: International Physical Activity Questionnaire - continuous daily energy expenditure score, high score means high AP

    The questionnaire allows the subject to be classified according to 3 levels of activity: inactive, moderate, high.

  42. Emotions: positive and negative

    Time frame: Before the surgery and at 6 and 12 month after

    positive and negative emotion assessed using the PANAS scale PANAS: Positive Affectivity and Negative Affectivity Scale - 2 scores from 10 to 50 - positive affectivity score = 50 best, negative affectivity score = 50 worst

  43. Emotions: food phobias

    Time frame: Before the surgery and at 6 and 12 month after

    food phobias using the FNS questionnaire FNS : Food Neophobia Scale -score from 10 to 70 - score of 70 = neophobia, i.e. less willingness to try new foods

  44. Emotions: loneliness

    Time frame: Before the surgery and at 6 and 12 month after

    loneliness using the ESUL questionnaire University of Laval Loneliness Scale - score from 20 to 80, score of 80 = most pronounced feeling of loneliness

  45. Changes in stool consistency

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Bristol stool scale Bristol scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools

  46. Changes in stool frequency

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Bristol stool scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools

  47. Changes in gastrointestinal symptoms

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Bristol stool scale

  48. Grade of hepatic steatosis

    Time frame: Before the surgery and at 12 month after

    Evaluation by FibroScan® but only for patients who had a FibroScan® performed before surgery.

  49. Grade of hepatic fibrosis

    Time frame: Before the surgery and at 12 month after

    Evaluation by FibroScan® but only for patients who had a FibroScan® performed before surgery.

  50. Eating behaviour and preferences : Behaviors

    Time frame: Before the surgery and at 6 and 12 month after

    Behaviors (emotional eating and cognitive restraint) using score from the DEBQ (Dutch Eating Behavior Questionnaire) a DEBQ : Dutch Eating Behaviour Questionnaire : 3 sub-scores: cognitive restriction, reactivity to external stimuli and emotionality from 1 to 5, score 5 = strong impact of eating behavior

  51. Hepatic metabolic flexibility

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed via the degree of alteration of MAMs (Mitochondia-Associated Membranes) in peripheral blood mononuclear cells (PBMCs), only for patients who had a FibroScan® performed before surgery.

  52. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    thyroid function: Thyroid function is assessed based on TSH levels in mIU/L (should be above 0.4 mIU/L and below 4.8 mIU/L), 2.

    The assessment for the research is whether the measures are within the limits or not (yes/no variable).

  53. Compliance and follow-up of advice given during the intervention

    Time frame: until month 12

    Based on the three 24-hour reminders completed by participants before each visit, the dietitian will classify participants into three categories: good, average or poor compliance.

  54. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    time spent selecting food at the buffet

  55. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    duration of ingestion

  56. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    ingestion speed

  57. Changes in stool consistency

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Likert scale Likert scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools

  58. Changes in stool consistency

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using gastrointestinal symptoms using GSRS Gastrointestinal Symptom Questionnaire - score 15 to 105, score 105=severe gastrointestinal symptoms

  59. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    complete blood count

  60. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    AST

  61. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    ALT

  62. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    gamma GT

  63. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    bilirubin

  64. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    alkaline phosphate

  65. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    creatinine

  66. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    uric acid

  67. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    ionogram results: Sodium (mmol/L) which should be between 136 and 145 Potassium (mmol/L) which should be between 3.4 and 4.5 Chlorine (mmol/L) which should be between 98 and 107 Bicarbonates (mmol/L) which should be between 22 and 29

  68. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    coagulation : prothrombin time

  69. Changes in stool frequency

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Likert scale

  70. Changes in stool frequency

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using gastrointestinal symptoms using GSRS : 15 questions with answers from No discomfort at all at Very severe discomfort (7 levels)

  71. Changes in gastrointestinal symptoms

    Time frame: Before the surgery and at 6 and 12 month after

    Assessed using Likert scale

  72. Changes in gastrointestinal symptoms

    Time frame: Before the surgery and at 6 and 12 month after

    gastrointestinal symptoms using GSRS

  73. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    total meal duration

  74. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    number of bites per minute

  75. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    total number of bites

  76. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    bites by food type

  77. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    food choices

  78. Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure

    Time frame: Before the surgery and at 6 and 12 month after

    Calorie intake consumed per minute of the buffet

  79. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    ionogram results:

    Anion gap = (Na+ + K+) - (HCO3- + Cl-) (mmol/L) which should be between 12 and 20

  80. Endocrine, digestive or intestinal hormones

    Time frame: Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)

    Blood sample to measure :

    Ghrelin pg/ml acylated ghrelin pg/ml

  81. Endocrine, digestive or intestinal hormones

    Time frame: Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)

    Blood sample to measure :

    GIP pmol/l total GLP-1 : pmol/L glucagon : pmol/L

  82. Endocrine, digestive or intestinal hormones

    Time frame: Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)

    Blood sample to measure :

    total PYY : ng/L

  83. Endocrine, digestive or intestinal hormones

    Time frame: Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)

    Blood sample to measure :

    leptin : ng/ml

  84. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    We will assess: insulin (mU/L)

  85. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    We will assess: triglycerides (mmol/L), HDL (mmol/L), LDL (mmol/L), ApoB (mmol/L), sphingolipid (mmol/L) and unesterified fatty acid(mmol/L)

  86. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    we will calculate: HOMA-IR (=insulin*glycarmia/22.5) and the total cholesterol/HDL cholesterol ratio.

  87. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    postprandial plasma markers: We will assess: insulin (mU/L)

  88. Nutritional status: Blood vitamin

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Blood vitamin status :

    For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

    The vitamins assessed are :

    • Vitamin B9 (mmol/L) should be above 10.4 mmol/L
  89. Nutritional status: Blood vitamin

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Blood vitamin status :

    For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

    The vitamins assessed are :

    • Vitamin B1 (nmol/L) should be above 78 nmol/L
  90. Nutritional status: Blood vitamin

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Blood vitamin status :

    For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

    The vitamins assessed are :

    • Vitamin C (µmol/L) should be above 25 µmol/L
    • Vitamin A (µmol/L) should be above 1.40 µmol/L
  91. Nutritional status : Blood mineral

    Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after

    Blood mineral status:

    • Iron (µmol/L) should be above 5.8µmol/L
    • Selenium (µmol/L) should be above 56µmol/L
    • Zinc (µmol/L) should be above 9.20µmol/L
  92. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    thyroid function: Thyroid function is assessed based on free thyroxine in pmol/L (should be above 11.9 pmol/L and below 21.9 pmol/L)

    The assessment for the research is whether the measures are within the limits or not (yes/no variable).

  93. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    thyroid function: Thyroid function is assessed based on free triiodothyronine in pmol/L (should be above 3.1 pmol/L and below 6.8 pmol/L).

    The assessment for the research is whether the three measures are within the limits or not (yes/no variable).

  94. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    Waist-to-hip ratio will be assessed

  95. Vital parameters

    Time frame: Before the surgery and at 6 and 12 month after

    resting heart rate

  96. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    coagulation : activated partial thromboplastin time

  97. Safety parameters

    Time frame: Before the surgery and at 6 and 12 month after

    coagulation : fibrinogen

  98. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    We will assess: total cholesterol (g/L)

  99. Cardio-metabolic profile parameters

    Time frame: Before the surgery and at 6 and 12 month after

    We will assess: HbA1c (mmol/mol),

Study contacts

Contact information is provided by the study sponsor or research team.

Berenice SEGRESTIN

CONTACT

Julie-Anne NAZARE

CONTACT

[email protected]

+33 6 88 87 09 62

Sponsors and collaborators

Lead sponsor

Hospices Civils de Lyon

Other

Registry information

Official study title

Randomised Controlled Trial Evaluating the Impact of a Pro-diversity Gut Microbiota Diet on Gut Microbiota, Eating Behaviour and Sensory Function in Patients Who Have Undergone Bariatric Surgery

Acronym: BariaGut Taste

Important dates

Study start
2025
Primary completion
2027
Study completion
2029
First posted
Dec 5, 2025
Registry last updated
Apr 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.