Human Intestinal Microbiota in Obesity and Nutritional Transition
Condition: Obesity
MeSH terms: Obesity
Study type: Interventional

Summary: 
      The objectives of this study are: 1-To qualify the relationship between the gut microbiota
      and the host nutritional and metabolic status during dietary transition.2-To define the
      impact of nutritional transition on the intestinal microbiota and identify metagenomics
      signatures of nutritional transition.
    

Detailed description: 
      French overweight (BMI > 27) and obese people (BMI > 30 kg/m2, N=50) will be submitted to a
      low calorie diet (1200 Kcal) for 8 weeks. This type of intervention is know to modify the
      metabolic phenotype and expected to change the gut microbiota. Nutritional interventions are
      planned for 6 months, each subject being studied before (base line), after the intervention
      (8 weeks) and 2 months after the low calorie diet has stopped and a diet of weight
      maintenance will be provided. This protocol will be implemented in the nutrition department
      of the Pitié Salpétrière Hospital in Paris, within the Centre de Recherche en Nutrition
      Humaine d'Ile-de-France, where patients will be followed on the clinical, biological and
      histological levels. Evaluation will include medical history, physical, and nutritional
      evaluations. They will be excluded of the protocol if they had evidence of acute or chronic
      inflammatory disease, infectious diseases, cancer and/or known alcohol consumption (> 20g per
      day), as well as other causes of liver, kidney or heart diseases. Physical evaluation will
      include weight, height, measures of waist/hip ratio, measure of blood pressure. At each time
      point, body composition will be measured by dual-energy X-ray absorptiometry performed with a
      total body scanner (Hologic QDR 2500 densitometer). Resting metabolic rate will be evaluated
      after a one-hour resting period in supine position. Oxygen consumption (VO2) and carbon
      dioxide production (VCO2), monitored over 30 min by using an open-circuit ventilated-canopy
      system (Deltatrac II monitor, Datex Instrumentarium Corp., Helsinki, Finland) calibrated with
      a reference gas. Blood samples will be obtained systematically for biological parameters
      including lipids (cholesterol, HDL-Chol, TG), insulin and glucose values and OGTT (enabling
      the determination of insulin sensitivity parameters, adipokines and inflammatory parameters
      such as leptin, adiponectin, IL-6, TNF alpha, SAA, hsCRP. Serum will be kept for all
      supplementary measures. The histopathological evaluation of subcutaneous adipose tissue will
      be performed to evaluate the adipocyte size and the degree of tissue inflammation. Stools
      samples will be collected for metagenomic studies.

      In addition, blood, urine and fecal water samples will be collected and frozen for subsequent
      metabonomic analysis, and fecal samples for metaproteomic assessment of the microbiota.
    

Intervention name(s): Caloric transition
Intervention type(s): Other
Intervention description(s): 6 week low calorie diet followed by 6 week stabilization period
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Primary purpose: Health Services Research
Keywords: obesity; low calorie diet; intestinal microbiota; inflammation (systemic and in adipose tissue); fat mass; Impact of nutritional transition on intestinal microbiota; relation between food intake, clinical parameters and intestinal microbiota