Bioavailability

Vitamin B1

Found in: Eggs, whole grain, meat, nuts

Absorbed in duodenum and jejunum
Inhibited by: alcohol and oxidants (example) in foods
Absorption increased: vitamin C

phosophated form needed to undergo Krebs Cycle

Vitamin B2

Found in: milk, dairy, meat, leafy vegetables, fortified cereals

Absorbed in duodenum and jejunum
95% of riboflavin in foods is present as FAD and FMN

NADH produced —> electron cycle

Easy to get enough of

Vitamin B3

Found in meat, poultry, fish, whole grains

Animal sources more bioavailable than plant sources
treating grains with alkaline
Can be made in the body from tryptophan (60 mg = 1 mg niacin)
Not bioavailable in corn
Used to make NAD, NADPH

Vitamin B5

Found in legumes, vegetables, whole grains, almost all foods

Absorbed in jejunum
Makes COA (not acetyl-COA, just COA)

Very easy to get enough of

Vitamin B6

Found in poultry, meats, egg yolks, fish, potatoes, chickpeas

Absorbed in jejunum
very bioavailable

Vitamin B7

Found in cooked eggs, nuts, seed, salmon, organ meats, gut bacteria

Absorbed in duodenum and jejunum
AVIDIN in RAW eggs inhibits because it strongly binds to biotin and blocks absorption

common in most foots

Vitamin B9

Found in leafy greens, legumes, fortified grains, orange juice

Absorbed in jejunum
Folate must be reduced to THF to be used
For it to be absorbed, all but ONE glutamate must be removed by GCP II enzyme
Folic acid is MORE bioavailable than food folate
1 ug = 0.6 ug folic acid with food = 0.5 ug folic acid without food

Vitamin B12

Found in animal products only, meat fish, eggs, NOT IN PLANTS
Absorbed in lleum (lower small intestine)

To be absorbed, 3 proteins needed (haptocorrin (salvia), intrinsic factor (stomach), transcobalamin from intestine) and HCI (stomach acid).

Vitamin C

Found in citrus fruits, fruits, vegetables

Destroyed in cooking, storage, etc.
Antioxidant —> reduces oxidative stress
Absorption —> ascorption/ascorbate: sodium-dependent transport
dehydroascorbic acid: uses glucose transporters, not sodium - transport
Glucose inhibits dehydroascorbic acid absorption (competing for same transporters)

Vitamin A

Found in fats, (it’s fat-soluble): cheese, milk, etc.

Received as “Vitamin A Esters”, cleaved by an enzyme called carboxyl esterase. To Liver

Vitamin E

Found in fruits, vegetables, nuts, seed oils

Absorbed in 
Vitamin E and Warfin  cause thin blood

Vitamin D

Found in sunlight, liver

Found as other sterols, can be synthesized by the body
cholecalciferol (D3) = most bio available form

Water-Soluble

B12 Complex, Vitamin C, flushed out daily, more likely to be deficient

Fat-Soluble

D E K A. more likely to cause toxicity