Wk3 Fiber Flashcards
Three insoluble fibers:
- lignin
- cellulose
- hemicellulose (some)
phenolic subunits
found in stems and seeds
insoluble
lignin
branched
insoluble
backbone of xylose, mannose, galactose
found in bran, whole grains, nuts
hemicellulose
soluble
backbone of galacturonic acid
found in apples, strawberries
completely degraded by gut bacteria
pectins
common food additive
completely fermented by gut bacteria
secreted by plants to close wounds
soluble
gums
oats, barley, mushrooms
fermented to SCFA
soluble
B-glucans
asparagus, leeks, onions, garlic, tomato, banana
prebiotics –> bifidobacteria
soluble
Fructans
similar to gums
soluble
holds lots of water
quite indigestible
psyllium
delays gastric emptying
increases transit time through GI
decreases nutrient uptake
soluble fiber
decreases GI transit time
increases fecal bulk
insoluble fiber
delay gastric emptying
decrease mixing of food with digestive enzymes
decrease nutrient diffusion
increase small intestine transit time
viscous fiber
How does fiber lower serum cholesterol:
increased excretion and reduced uptake of bile acids
How does fiber decrease lipid absorption?
prevents micelle formation
Three SCFA’s:
acetate
propionate
butyrate
SCFA receptor on a lot of cells that decreases inflammatory response:
GPR43
