Topic 7 - Harder stuff

Question 1

Low FODMAP diet

Answer 1

• Leads to increased Actinobacteria
• A high FODMAP diet has a decreased abundance of bacteria that are involved in gas consumption
• Leads to a reduction in IBS

Question 2

Fibre & prebiotics

Answer 2

• Leads to increased microbiota diversity AND SCFA production
• Leads to a reduction in Type 2 diabetes & cardiovascular disease

Question 3

Difference in microbiomes b/w breastfed and bottle-fed babies

Answer 3

• Breast fed babies have a lot more Actinobacteria (Bifidobacterium, lactobacillus)
• Have HMOs which are digested by specific bacteria in infant GI tract and act as prebiotics by enriching certain beneficial bacteria
• They also promote the release of SCFAs that feed on infant gut
• Bottle fed babies have more diverse microbiota; more Bacteroides and Clostridial species
• More pathogens

Question 4

What are the 6 benefits of HMOs?

Answer 4

• They help Bifidobacteria to grow & proliferate
• They competitively exclude pathogens from binding
• Decoy for other microbes to attach to so they can be removed
• Macronutrient digestion
• Development of mucus layer
• HMOs affect bifidobacteria & promote growth of SCFA

Question 5

What are the 3 key effects of SCFAs?

Answer 5

• They help the growth of enterocytes and use them for energy harvest
• Involved with anti-inflammatory cytokines
• Involved in immune modulation

Question 6

How are gut microbes involved in immune development?

Answer 6

• Induction, training, & function of the immune system is facilitated by microbes
• Allows immune system to work out which microbes are good and which cause disease
• If the immune system does not work properly, food allergies and autoimmune disease can develop

Question 7

How does the gut microbiome in the first few weeks compare to later in life?

Answer 7

• The gut microbiome is dynamic in the first few weeks of life; lower diversity, higher variability
• Gut microbiome transitions to higher diversity, lower variability as development proceeds

Question 8

What are 3 things that can lead to disruptions on gut microbiota?

Answer 8

1) infections
2) antibiotics
3) changes in diet

Question 9

What types of bacteria are found in the placenta?

Answer 9

• nonpathogenic commensal microbiota
• firmicutes, tenericutes, proteobacteria, bacteroidetes, fusobacteria

Question 10

What are the first colonizers of the infant gut in vaginal birth?

Answer 10

facultative anaerobic bacteria, like Staphylococcus

Question 11

What is the bacterial composition of C-section babies like?

Answer 11

• less diverse
• absence of Bifidobacterium and Bacteroides species

Question 12

What are some health consequences of C-section babies?

Answer 12

• increased risk of allergies and asthma
• associated with higher body mass and childhood obesity

Question 13

What are the 4 factors that are known to alter gut microbiome & associated with higher rate of C-section surgery?

Answer 13

• Diet
• Antibiotic exposure
• Gestational age
• Host genetics

Question 14

What are some negative effects of being a preterm infant?

Answer 14

• Higher level of potential pathogens
• High interindividual variability
• Reduced microbial diversity
• Harbour increased levels of facultative anaerobic microorganisms (e.g. Lacobacillus)
• Delayed maturation of immune system (higher risk of infection)
• Lower levels of bifidobacterium
• Necrotizing enterocolitis (NEC) is a serious gastrointestinal disease
• Increase in proteobacteria and decrease in firmicutes before diagnosis of NEC

Question 15

What are some of the short vs long term benefits of breastfeeding?

Answer 15

Short-term: lowered risk of infectious diseases in childhood
Long-term: lower risk of obesity, protection against type 2 diabetes, increased performance on IQ tests

Question 16

How does the gut microbiota change after the introduction of solid foods?

Answer 16

• More complex microbiota
• Bifidobacteria proportions drop as microbiota diversifies
• Facultative anaerobes decrease and strictly anaerobic clostridia increase
• Proportions of bacteroides remain unchanged and are one of the most predominant groups in infant after weaning
• Higher prevalence of butyrate-producing bacteria

Question 17

How do the functions of the microbiota differ in children vs adults?

Answer 17

• Children → ongoing physical development; DNA replication, repair,
• Adults → inflammation & increased risk of adiposity (obesity); synthesis of Vitamin B12, folate

Question 18

What are the main external factors that can affect the composition of the microbiota in healthy adults?

Answer 18

• Infection
• Major dietary changes
• Antibiotic therapy
• Medications

Question 19

What kind of elderly person has the highest diversity in gut microbiota?

Answer 19

An older adult living in a community setting who consumes a low fat / high fibre diet that includes a variety of foods

Question 20

Kids have higher _____ than adults

Answer 20

Bifidobacterium

Question 21

What is the gut microbiota of old people like?

Answer 21

• Higher Bacteroidetes (more than Firmicutes) and
• Proteobacteria
• Less Actinobacteria (esp Bifidobacterium)
• A centenarian has more pathobionts and less butyrate-producing bacteria
• Lower microbial diversity is associated with HIGHER frailty + inflammation
• In old people, composition of gut microbiota shifts towards LESS DIVERSITY and more proinflammatory species