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Diet, Microbiota and Metabolic Health by Renée Wilson


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Renée Wilson, Registered Dietitian and PhD Candidate at University of Otago, New Zealand. Presented at the 1st International Symposium on Kiwifruit and Health:

This cross-sectional pilot study aims to determine whether or not there are any differences between the gut microbiota of people with normal glucose tolerance, pre-diabetes and type 2 diabetes.

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Diet, Microbiota and Metabolic Health by Renée Wilson

  1. 1. Diet, Microbiota and Metabolic Health Renée Wilson, PhD Candidate & Registered Dietitian Supervisors: Dr Jinny Willis, Professor Richard Gearry, Professor Gerald Tannock, Dr Paula Skidmore
  2. 2. The Human Microbiota
  3. 3. Human versus Microbial Cells Semenkovich et al, Diabetes, 2015, 1-11
  4. 4. Genes and Genetic Variation Semenkovich et al, Diabetes, 2015, 1-11
  5. 5. The Gut Microbiota
  6. 6. Classification • Bacteroidetes • Firmicutes • Actinobacteria • Proteobacteria • Verrucomicrobia
  7. 7. Colonisation of the Gut Microbiota • Colonisation Mode of delivery Breast vs formula feed (DIET) Environment Drug therapies • 3 years for an adult-like microbiome.
  8. 8. The large bowel is a fermenter (continuous culture; chemostat) IN: indigestible components of food OUT: waste and bacteria Fermentation Calories Endogenous substrates Gases “gut microbes represent an extended reservoir of metabolic capabilities” Owyang and Wu, 2014
  9. 9. How we Study the Microbiota We have been interested in the gut microbiota since the 1900’s. However, culture based methods have limitations! Culture-independent sequencing based methods were developed in the 90’s.
  10. 10. Bioinformatics
  11. 11. The Gut Microbiota and Metabolic Health Diabetes Obesity IBD Allergic diseases Mental health
  12. 12. Previous Research Limitations • Different study populations Small sample sizes Heterogeneous populations (lack of age and gender balance) • Methodological issues Variety of methods for characterizing gut microbiota - comparisons between studies difficult • Incomplete data on diabetes medication • Limited data on dietary intake and physical activity
  13. 13. Heterogeneity of Phenotype in Clinical Cohorts Sato et al, 2014
  14. 14. Diabetes • There are 3 main types of diabetes: – type 1 diabetes mellitus (T1DM) – type 2 diabetes mellitus (T2DM) – gestational diabetes. • Poorly managed diabetes leads to serious complications and early death.
  15. 15. Type 2 Diabetes Mellitus • T2DM comprises 90% of people with diabetes around the world. • In T2DM, either the body doesn’t produce enough insulin, or the cells in the body don’t recognise the insulin that is present. The end result is high levels of glucose in your blood (IDF, 2015). • For many people (but not all) it can be prevented through following a healthy lifestyle. • There is a clear link between T2DM and overweight/obesity, hypertension and dyslipidaemia i.e. the Metabolic Syndrome.
  16. 16. Diabetes around the World
  17. 17. Diabetes: A Global Emergency
  18. 18. Diabetes in New Zealand Data are % (95% CI) Coppell et al, NZMJ, 2013
  19. 19. Current Research Study Cross-sectional pilot study. To determine whether or not there are any differences between the gut microbiota with normal glucose tolerance (NGT), pre-diabetes and T2DM. – Define gut microbiota composition associated with NGT, pre-diabetes and T2DM. – Identify dietary associations with gut microbiota composition with particular emphasis on fruit and vegetables intake. – Establish the feasibility of an intervention study with kiwifruit to favourably alter gut microbiota composition and therefore impact on glucose tolerance.
  20. 20. Study Groups Normoglycaemia (n=30) Pre-diabetes (n=20) Adults > 18 yrs Type 2 Diabetes (n=20) - Metformin only
  21. 21. Data and Sample Collection • Questionnaires • Blood, urine, stool sample • 4 day weighed food diary • Anthropometric data
  22. 22. Benefits and Outcomes • Relationships between glucose tolerance, dietary intake, gut microbiota characteristics and urine metabolite profiles. • An indication whether a dietary intervention to alter gut microbiota provides a feasible prospect for type 2 diabetes therapy.
  23. 23. Diet and the Microbiota De Filippo et al, PNAS, 2010; 14691-14696
  24. 24. Loss of Microbial DiversityLoss of microbial diversity
  25. 25. Diet and the MicrobiotaDiet and the Gut
  26. 26. Manipulation of the Gut Microbiota • Prebiotic • Probiotic • Antibiotic • Faecal microbiota transplant
  27. 27. Prebiotic Research What is a prebiotic? A prebiotic is a type of fibre that passes through the GI tract undigested and stimulates the growth and/or activity of certain ‘good’ bacteria in the large intestine. E.g. Prebiotics include inulin and galacto-oligosachairdes
  28. 28. Probiotics • "live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host“ (WHO, 2001) • May enhance barrier function, compete with pathogens, modulate immune function.
  29. 29. Antibiotics • Kill bacteria. • Antibiotics have been found to alter the human gut microbiota, with effects that are rapid and sometimes persistent. • Differing rates of antibiotic use worldwide. • Bacteria can become resistant to antibiotics.
  30. 30. Faecal microbiota transplant Faecal transplant
  31. 31. Microbial Population Diet Antibiotic use Host genome Hygiene SCFA Production Increased energy harvest Obesity Pre-diabetes Type 2 Diabetes Gut Permeability Inflammation Weight gain/ ↑insulin resistance Impaired insulin & glucose tolerance