BIOM30001 Lecture Notes - Lecture 8: Bacteroides, Short-Chain Fatty Acid, Lactobacillus
Diseases & Disorders 1950-2000
Infectious diseases eradicated due to improved sanitation, treatment and health care
systems
○
Immune dysfunction diseases (allergies, autoimmune disease) on the rise - thought to be
genetic but now know there is major environmental influence on immunity
○
As some diseases decrease, others increase.
•
Decreasing incidence of asthma with increasing birth order
○
The bigger the family, the less asthma
○
Other studies showed that children in childcare centres had less asthma
○
Suggested that immune system is developed/strengthened by exposure to
pathogens/other children/infectious diseases, preventing emergence of allergies
○
E.g. Helminth infections (prevalent in children everywhere) may induce anti-
inflammatory immune response - prevents emergence of immune conditions
○
Family size association with allergy - David Strachan, 1989
•
Cleanliness
○
Vaccinations
○
Antibiotic use
○
Sanitation of our environment due to:
•
--> Reduced exposure to infectious agents
--> Deregulated immune response
Flaws in this hypothesis: pathogens also induce inflammatory response; Japan has high
antibiotic use but low allergy levels. Hypothesis thus extended to:
•
Hygiene Hypothesis
Graham Rook, 2003
•
Vital microbial exposure is NOT infectious
•
Dependent on our natural microbiota
•
Microbes co-evolved with the immune system
•
Development
○
Function
○
Humans are dependent on microbes for immune system
•
Old Friends (Microbiota) Hypothesis
Diet drives changes in the microbiota
•
Diet Hypothesis
8: Gut Microbiota, Health & Disease
Tuesday, 11 August 2015
11:10 pm
Frontiers Page 1
Diet drives changes in the microbiota
•
Directs the development and function of the immune system
•
Nutritional Transition: Changes in economic, demographic, epidemiological factors lead to
changes in physical activity, dietary patterns.
•
Changes in calorific intake: progression from blue to red
•
Driven by economic factors (wealth, globalisation, technology), high birth rate to low birth
rate, epidemiological changes (less famine/disease epidemics, now have constant
environment esp in wealthy societies)
•
High fat
○
High sugar
○
Highly refined
○
Highly processed
○
low in fibre
○
Went from a high fibre diet to a diet that is:
•
Fibre and carbs are the most significant variable of the diet due to the complexity of
breakdown requited
•
Is diet the basis of increased 'Western world' disease?
Gut Microbiota
Frontiers Page 2
Document Summary
Infectious diseases eradicated due to improved sanitation, treatment and health care systems. Immune dysfunction diseases (allergies, autoimmune disease) on the rise - thought to be genetic but now know there is major environmental influence on immunity. Family size association with allergy - david strachan, 1989. Decreasing incidence of asthma with increasing birth order. Other studies showed that children in childcare centres had less asthma. Suggested that immune system is developed/strengthened by exposure to pathogens/other children/infectious diseases, preventing emergence of allergies. Helminth infections (prevalent in children everywhere) may induce anti- inflammatory immune response - prevents emergence of immune conditions. Flaws in this hypothesis: pathogens also induce inflammatory response; japan has high antibiotic use but low allergy levels. Humans are dependent on microbes for immune system. Directs the development and function of the immune system. Nutritional transition: changes in economic, demographic, epidemiological factors lead to changes in physical activity, dietary patterns. Changes in calorific intake: progression from blue to red.
