Fat Soluble Vitamins

Question 1

Retinal

Answer 1

important for vision
gets converted into 11-cis-retinal and then rhodopsin
beta-carotene (50%) converted into retinal in small intestine

Question 2

Retinol

Answer 2

required for reproduction, utilized in testes/ovaries

can be made from retinal or retinyl esters in the liver

Question 3

All trans retinoic acid

Answer 3

required for gene activation, growth, differentiation and maintenance of epithelial tissue (GI, lungs, cornea, e.g.)
made from retinol

Question 4

Vitamin A absorption

Answer 4

70-90% retinyl esters
20-50% beta-carotene 
(iron needed for beta-carotene monooxygenase)
increased by cooking/processing
decreased by fiber, esp pectin

Question 5

Vitamin A target tissues

Answer 5

70-75% to:
bone marrow
muscle
lungs 
kidneys
adipose (stores 15-20%)
the rest goes to the liver (stored as retinyl palmitate in stellate cells)

Question 6

Vitamin A functions

Answer 6

vision - rhodopsin
gene transcription - regulates growth of epithelium, bones, teeth (all trans retinoic acid); reproductive health (retinol)
RBC production
immune function

Question 7

Retinoic acid

Answer 7

GENE TRANSCRIPTION
regulates enzymes re:cell growth, differentiation, apoptosis
- incr gap jct protein connexin
- supports differentiation of keratinocytes, immune cells, and stem cells

Question 8

Vitamin A DRI

Answer 8

females - 700 mcg/2333 IU

males - 900 mcg/3000 IU

Question 9

Vitamin A testing

Answer 9

serum retinol

serum RBP

Question 10

Vitamin A deficiency

Answer 10

primary = decr intake; secondary = lipid malabsorption

conjunctival xerosis (bitot's spots)
excess keratinization
incr susceptibility to infx
night blindness
delayed growth

Question 11

Vitamin A toxicity

Answer 11

> 25,000 IU/day
liver damage 
- hepatocyte hyperplasia and hypertrophy
- elevated liver enzymes
N/V, HA
bone/joint pain
incr risk of birth defects
SE - skin yellowing (carotenoids - no risk of toxicity)

Question 12

Vitamin A food sources:

retinol/retinyl esters

Answer 12

liver
butter
eggs
fortified dairy
fish - sardines, tuna, herring
fortified cereal grains

Question 13

Vitamin A food sources:

Beta-carotene

Answer 13

dandelion greens
spinach
collard, kale
turnip greens
pumpkin
winter squash
sweet potato
carrot
raw cantaloupe

Question 14

Vitamin D active form

Answer 14

calcitriol

1,25-dihydroxycholecalciferol

Question 15

Vitamin D metabolism

Answer 15

7-dehydrocholesterol converted by UVB light to
cholecalciferol (D3) converted by liver to
25-hydroxycholecalciferol converted by kidneys to
1,25-dihydroxycholecalciferol

Question 16

Vitamin D regulation

Answer 16

kidney hydroxylation regulated by:

• PTH (incr vit d production in re:to decr calcium)
• fibroblast-like growth factor 23 (decr vit d production)
• negative feedback inhibition

Question 17

Vitamin D RDA

Answer 17

1-70 yo = 600 IU (15 mcg) harvard says 1000-2000 IU
> 70 = 800 IU (20 mcg)
UL = 4000 IU (100 mcg)

does not pass through breast milk
- 400 IU/day for infants

Question 18

Vitamin D food sources

Answer 18

liver
egg yolk
fortified milk, margarine, butter, cereal
mushrooms
fatty fish - salmon, sardines, herring

Question 19

Vitamin D absorption

Answer 19

50% ingested = absorbed, mostly in distal SI

• 40% then incorporated into micelles, transported via chylomicrons —-> adipose/muscle
• 60% then transported via it D-binding protein —> liver

Question 20

Vitamin D functions

Answer 20

non-genomic - binds to membrane receptor to affect calcium uptake

genomic - binds to cellular receptor (VDR) in immune cells, prostate, colon, breast, skin, pancreas, adrenal glands, brain, muscle

Question 21

Vitamin D functions (2)

Answer 21

calcium balance 
cell differentiation
gene transcription
immune system modulator
insulin secretion
blood pressure regulation (suppresses renin ---> decr angiotensin II)

Question 22

Vitamin D deficiency

Answer 22

rickets (children) - inadequate calcification

osteomalacia (adults) - soft deformed bones, pain, weakness

Question 23

Risks for vitamin D deficiency

Answer 23

reduced UV availability and skin penetration
impaired skin synthesis (aging)
kidney disease
low dietary intake/absorption
tissue sequestering (obesity)

Question 24

Vitamin D excess/toxicity

Answer 24

elevated blood calcium —> calcification of soft tissue
to check status - serum 25-OH vitamin D
- up to 80-100 ng/mL appears to be safe

Question 25

Vitamin E RDA

Answer 25

15 mg/day UL = 1000 mg (1 IU = 0.66 mg of d-alpha-tocopherol and 0.45 mg of dl-alpha tocopherol))

Question 26

Vitamin E absorption

Answer 26

- tocopherols = free in food, up to 80% absorbed | - tocotrienols = esterified and must be hydrolyzed,

Question 27

Vitamin E functions

Answer 27

antioxidant stabilization of cell membranes (protects unsaturated FAs) protects LDL from oxidation {regenerated by ascorbic acid)

Question 28

Vitamin E deficiency

Answer 28

assess via serum vitamin E

Question 29

Vitamin E toxicity

Answer 29

rarely seen | possibly ---> diarrhea, fatigue, double vision, muscle weakness

Question 30

Vitamin E food sources

Answer 30

``` leafy greens PUFA plant oils almonds sunflower seeds wheat germ, whole grains egg yolks avocados tomatoes ```

Question 31

Vitamin K forms

Answer 31

K1 = phylloquinone - best food source = plants K2 = menaquinone (active form in the body) - low amt in food, most = converted from K1 by gut bacteria (bacteroides fragile, eubacterium, propionibacterium) and in vasculature

Question 32

Vitamin K2

Answer 32

15x more active than other forms better absorbed, longer biological activity = predominant form found in body tissues

Question 33

Vitamin K AI (adequate intake)

Answer 33

``` females = 90 mcg/day males = 120 mcg/day ```

Question 34

Vitamin K absorption

Answer 34

``` phylloquinones = easily absorbed via micelles menaquinones = passive diffusion in lower GI ``` ``` delivered via chylomicrons to: lungs kidneys bone marrow adrenal glands ```

Question 35

Vitamin K functions

Answer 35

- facilitates carboxylation with glutamate residues - -- subsequent incr negative charge allows calcium to bind to proteins and activate (as seen in clotting factors, osteocalcin in bone, and matrix Gla protein in vasculature)

Question 36

Vitamin K functions (2)

Answer 36

blood clotting bone health - synthesis of osteocalcin; prevents bone loss - integration of ca into bones - prevents ca depot in vasculature and maintains elasticity

Question 37

Vitamin K excess

Answer 37

uncommon no known toxicities high doses can decr anti-clotting medication efficacy

Question 38

Vitamin K deficiency

Answer 38

reduced clotting time (easy bruising and bleeding) | osteoporosis

Question 39

Vitamin K food sources

Answer 39

leafy greens | brassicas