Fiber - Skildum

Question 1

What does fiber refer to?

Answer 1

carbohydrates that are not digestible

Question 2

What four things does fiber affect?

Answer 2

• GI motility
• absorption of nutrients
• the GI microbiome
• immunity

Question 3

If present in a polymer of glucose, which of the bonds below is not a substrate for human carbohydrate digestive enzymes?

• A. alpha- 1,4
• B. alpha-1,6
• C. beta-1,4
• D. alpha-1,1

Answer 3

C. beta-1,4.

Lactose has a beta-1,4 bond, but it is a glucose / galactose disaccharide, not a glucose polymer.

• Alpha 1,4: amylase, glucoamylase
• Alpha 1,6: sucrase – isomaltase complex
• beta-1,4: lactase
• alpha 1,1: trehalase

Question 4

Indigestible fiber can be converted to _______ by bacteria in the lumen of the gut.

• A. glucose
• B. alanine
• C. acetate
• D. hydrochloric acid
• E. phenol

Answer 4

C. acetate

Question 5

What component of human breast mild can be converted to short chain fatty acis in the gut of a healthy infant?

• A. Triglycerides
• B. Phospholipids
• C. Protein
• D. Oligosaccharides
• E. Lactose

Answer 5

A. Oligosaccharides

Question 6

Which cytokine acts as a brake on inflammation?

• A. TNF-alpha
• B. IL-2
• C. IL-10
• D. G-CSF
• E. IL-6

Answer 6

C. IL-10

Question 7

How is fiber classified?

Answer 7

• Fiber is classified as either soluble or insoluble.
  
  • Insoluble fibers are non-viscous
  • Soluble fiber can be viscous or non-viscous

Question 8

What type of insoluble fiber is a major component of plant cell walls? It is abundant in bran, beans, nuts, root vegetables and apples.

Answer 8

Cellulose

Question 9

What insoluble fiber has branched polymers of phenolic subunits? It found in the stems and seeds of fruits.

Answer 9

Lignin

Question 10

What insoluble fiber is a branched polymer abundant in bran, whole grains, and nuts?

_{(With acidic side chains it can be soluble.)}

Answer 10

Hemicellulose

Question 11

What soluble fiber is made up of branched polymers abundant in apples, strawberries and apples? It is almost completely degraded by gut bacteria.

Answer 11

Pectin

Question 12

What soluble fiber is secreted by plants to close wounds. They are common food additives, and are completely fermented by gut bacteria.

Answer 12

Gums, a.k.a. hydrocolloids

Question 13

What soluble fiber is found in oats, barley and mushrooms. They are fermented by gut bacteria to short chain fatty acids.

Answer 13

Beta-glucan

Question 14

What soluble is found in asparagus, leeks, onions, garlic, tomato and banana? They are prebiotics, promoting the growth of bifidobacteria (gram positive anaerobes) in the gut.

Answer 14

Fructans, a.k.a. polyfructose

Question 15

What soluble fiber has a structure similar to gums? It is quite indigestible, holds a lot of water, and is found in many grains.

Answer 15

Psyllium, a.k.a. mucilage

(in Metamucil)

Question 16

What two insoluble fibers are found in the exoskeletons of insects and crustaceans? Their structure is similar to cellulose, but with amino group substitutions on the glucoses.

Answer 16

Chitin and chitosan

Question 17

What are four types of resistant starch that are inaccessible by amylose and amylopectin?

Answer 17

• plant cell walls
• starch granules within cells
• retrograde starch (cooked then cooled)
• chemically crosslinked starch

Question 18

What polymer of glucose and sorbitol is used as a food additive to replace sugar? It is soluble, and partially fermented by the gut.

Answer 18

Polydextrose

Question 19

What effects do soluble fibers have on GI functions?

Answer 19

• delays gastric emptying
• increases transit time through the GI
• decreases nutrient uptake

Question 20

What effects do insoluble fibers have on GI functions?

Answer 20

• decreases intestinal transit time
• increases fecal bulk

Question 21

What effects do viscous fibers have on GI functions?

Answer 21

• delay gastric emptying
• decrease mixing of food with digestive enzymes
• decrease nutrient diffusion
• increases small intestine transit time

Question 22

What are the beneficial effects of a diet high in fiber?

Answer 22

• Decreased lipid absorption
  
  • Fiber prevents micelle formation required for fat uptake.
• Lowered serum cholesterol concentrations
  
  • Increased excretion (and reduced uptake) of bile acids
• Gut microbiome
  
  • Fiber promotes the growth of lactobacilli and bifidobacteria
  • Fiber is used by bacteria to generate short chain fatty acids
• Increased fecal bulk
  
  • Decreased intraluminal pressure decreases diverticulitis

Question 23

Through interacting with which receptor do short-chain fatty acids inhibit inflammation?

Answer 23

GPR43

Short chain fatty acids (SCFA) produced by fermentation of dietary fiber affect immune cells by acting as a ligand for GPR43, and by inhibiting histone deacetylases (HDAC).

Question 24

What effect does activation of GPR43 have in adipocytes?

Answer 24

Activation by short chain fatty acids inhibits insulin dependent storage of fatty acids, increasing their use by other tissues.

Question 25

What diet is best for infants? * A. Cow milk + formula * B Raw cow milk * C. Breast milk * D. Soy based formula * E. RC Cola

Answer 25

C. Breast milk | ("Breast is best!")

Question 26

Which dietary fiber decreases intestinal transit time? * glucan * lignin * pectin * psyllium * fructan

Answer 26

Lignin (Lignin is insoluble; all the others are soluble.)