Beta-glucan and Insulin Sensitivity in Obese Humans
Condition: Obesity
MeSH terms: Insulin Resistance; Hypersensitivity
Study type: Interventional

Summary: 
      Obesity is an important health problem of modern civilization. In Western societies, almost
      half of the adult population has problems with an increased body weight. Products containing
      nutritional fiber has been used by humans for thousands of years. However, beta-glucan as
      biologically active compound, present in these products, has been identified relatively
      lately. This substance is a polymer of glucose and is present in two forms: 1,3D-1,6D and
      1,3D-1,4D.

      Water-insoluble beta-glucan (1,3D-1,6D) has immunomodulatory properties. The aim of the study
      was the assessment of the influence of beta-glucan 1,3D-1,6D added to the low-calorie diet on
      insulin sensitivity and the expression of selected proinflammatory cytokines in adipose
      tissue and peripheral blood mononuclear cells (PBMC) in obese humans with normal glucose
      tolerance.

      The study group consisted of 40 subjects with marked overweight or obesity (body mass index,
      BMI > 28 kg/m2), without serious concomitant diseases not taking drugs affecting glucose or
      lipid metabolism, nonsmokers. Only volunteers, who gave written informed consent, after
      receiving a full information about the aim and the design of the study, were recruited.

      At the beginning of the study, after subjects' qualification to the project and before the
      dietary intervention, the investigators performed:

        -  anthropometric measurements.

        -  oral glucose tolerance test.

        -  euglycemic hyperinsulinemic clamp.

        -  PBMC isolation before and after the clamp.

        -  biopsy of subcutaneous adipose tissue before the clamp.

        -  isolation of mRNA from PBMC and adipose tissue. Then, the expression of the selected
           genes with the Real Time PCR was measured.

        -  After the initial visit, participants received detailed instructions about low-calorie
           diet, with the aim of reduction of 5-7% of body weight and the examples of menu for 14
           days.

      Then, participants were randomly assigned to a group receiving or not beta-glucan
      preparation, as a addition to the low-calorie diet. Each group consisted of 20 subjects.
      Subjects assigned to a group receiving beta-glucan, received the preparation (BETA GLUCAN
      1,3-1,6 Laboratoria Natury 500mg) together with the detailed instruction of its usage. This
      preparation is used as a non-prescription diet supplement, and the dose of 500 mg daily is
      indicated by the manufacturer.

      After 12 weeks of low-calorie diet, without or with beta-glucan, all the examinations
      performed at the beginning of the study were repeated.
    

Detailed description: 
      Obesity is an important health problem of modern civilization. In Western societies, almost
      half of the adult population has problems with an increased body weight. In Europe, obesity
      occurs in 10-20% males and 15-25% females. In Poland, obesity is present in about 20% of
      population.

      Products containing nutritional fiber has been used by humans for thousands of years.
      However, beta-glucan as biologically active compound, present in these products, has been
      identified relatively lately. This substance is a polymer of glucose and is present in two
      forms: 1,3D-1,6D and 1,3D-1,4D.

      Water-insoluble beta-glucan (1,3D-1,6D) has immunomodulatory properties. It stimulates host
      defense against viral, bacterial and parasitical infections through binding with the specific
      receptors located on the immune system cells surface in many animal models. There are data
      that beta-glucan 1,3D-1,6D affects both innate and acquired immune response also in humans.

      The aim of the study was the assessment of the influence of beta-glucan 1,3D-1,6D added to
      the low-calorie diet on insulin sensitivity and the expression of selected proinflammatory
      cytokines in adipose tissue and peripheral blood mononuclear cells (PBMC) in obese humans
      with normal glucose tolerance.

      The study group consisted of 40 subjects with marked overweight or obesity (body mass index,
      BMI > 28 kg/m2), without serious concomitant diseases not taking drugs affecting glucose or
      lipid metabolism, nonsmokers. Only volunteers, who gave written informed consent, after
      receiving a full information about the aim and the design of the study by the research
      personnel were recruited.

      At the beginning of the study, after subjects' qualification to the project and before the
      dietary intervention, the investigators assessed:

        -  anthropometric measurements: BMI, waist-to-hip ratio (WHR), full physical examination.

        -  body composition with Tanita TBF-511 Body Fat Analyzer.

        -  glucose tolerance with the oral glucose tolerance test.

        -  insulin sensitivity with the euglycemic hyperinsulinemic clamp technique.

        -  before and after the clamp, additional 6 ml of blood was collected, and PBMC isolation
           was performed.

        -  before the clamp, a biopsy of subcutaneous adipose tissue was performed.

        -  isolation of mRNA from PBMC and adipose tissue was performed. Then, the expression of
           the selected genes with the Real Time PCR In adipose tissue was measured measured.

        -  additionally, serum concentrations of ghrelin, peptide Y-Y3-36, citruline and intestinal
           fatty acid-binding protein was assessed.

      After the initial visit, participants received detailed instructions about low-calorie diet,
      with the aim of reduction of 5-7% of body weight and the examples of menu for 14 days.

      Then, participants were randomly assigned to a group receiving or not beta-glucan
      preparation, as a addition to the low-calorie diet. Each group consisted of 20 subjects.
      Subjects assigned to a group receiving beta-glucan, received the preparation (BETA GLUCAN
      1,3-1,6 Laboratoria Natury 500mg) together with the detailed instruction of its usage. This
      preparation is used as a non-prescription diet supplement, and the dose of 500 mg daily is
      indicated by the manufacturer.

      Analysis of the compliance to the dietary indications and analysis of body composition was
      performed every 2 weeks.

      After 12 weeks of low-calorie diet, without or with beta-glucan, all the examinations
      performed at the beginning of the study were repeated.
    

Intervention name(s): low calorie diet plus beta-glucan; low-calorie diet
Intervention type(s): Dietary Supplement; Other
Intervention description(s): beta-glucan 1.3D-1.6D, together with a low calorie diet, 500 mg once daily for 12 weeks; low-calorie diet only for 12 weeks.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: insulin sensitivity; adipose tissue; inflammation