Gut Lec: Diet, Microbiome, Health

What are the negative effects of an unhealthy diet?

• Obesity

• Heart disease

• Diabetes

• Cancer

What are the three parts of the small intestine?

• Duodenum

• Jejunum

• Ileum

What are the 3 accessory organs of the G.I. tract? What are their functions

• Liver — powerhouse of various functions (manufacturing, detoxifying, conversion, storage), produces bile

• Gallbladder — stores bile

• Pancreas — aids digestion and regulates blood sugar, secrets powerful enzymes and hormones

What are the three main macronutrients of a healthy human diet? What else is needed?

• Carbohydrates (50%)

• Proteins (15%)

• Fats (20%)

• Water

• Vitamins/Minerals

• Fibers

What is the microbiome?

• “6th vital organ”

• Bacteria, viruses, fungi, archaea that live in the gut

What is the Human Microbiome Project?

Fund that developed resources to study microbiomes

What is metagenomics?

Study of all gene material from organisms in an environment

What is proteomics?

Study of all proteins in a cell, tissue, or organism

What is metabolomics?

Study of small molecules within in organism, cell, or tissue

What is pharmaco-microbiomics?

Study of how microorganisms in the gut interact with drugs

What are prebiotics?

Food parts that are undigested but usable by gut bacteria

What are probiotics?

Specific living microorganisms (sour bread starter, yogurt)

What is unique about the human microbiome? (2)

• Diverse

• Host-specific

What is eubiosis?

Healthy gut

What is dysbiosis?

Unhealthy gut

What are the three dominant phyla in the gut microbiome?

Bacteroidetes, firmicutes, actinobacteria

What does a high F/B ratio reveal? What about a low F/B ratio?

• High F/B = fat-rich diet (obesity)

• Low F/B = fiber-rich diet

What are the four main communication pathways between the gut and organs?

• Metabolic secretions (SCFAs, BAs)

• Immune system (cytokines, chemokines)

• Nervous system (vagus nerve)

• Endocrine system (serotonin)

What are SCFAs? What is their main purpose?

• Nondigestible complex carbs

• Most abundant: acetate, propionate, butyrate

• Act as signaling molecules, increase insulin secretion, anti-inflammation

What are BAs? What are the primary and secondary BAs?

• Bile salts synthesized from cholesterol by hepatocytes and stored in gallbladder

• Primary: CA, CDCA

• Secondary: DCA, LCA

How does a fiber-rich diet regulate the level of BAs in the gut?

• Too many BAs is bad

• Fiber pushes out BAs

• LDL cholesterol is used to make new BAs

How does the gut communicate with the brain? (4)

• NTs

• Metabolites (SCFAs, etc.)

• Cytokines

• HPA axis

How does the gut communicate with the heart? (4)

• SCFAs

• ImP

• Inflammation

How does alcohol negatively impact gut bacteria?

• Changes diversity

• Creates bad bacteria

• Kills good bacteria

• Increases risk of immune dysfunction