Vit A

Question 1

initial transport of the fat soluble vitamins happens in the ___

Answer 1

chylomicron

Question 2

There is no control on amount taken up for fat soluble vitamins because of ___cytosis

Answer 2

pino

Question 3

what are the 3 forms of Vit A found in the body?

Answer 3

retinol, retinal, retinoic (and preformed vit A from animal foods–>retinol as retinyl ester)

Question 4

only ___% of carotenes in foods are provitamin A

Answer 4

10; these are carotenes in plant-based foods

Question 5

this provitamin A, when split in half, obtain 2 retinol

Answer 5

beta carotene

Question 6

this provitamin A only forms one retinol

Answer 6

alpha-carotenes

Question 7

examples of non provitamin A carotenes (provide no retinols)

Answer 7

lycopene (prostate cancer reduction) and lutein (role in eye)

Question 8

what is the conversion factor for b-carotene –>retinol?

Answer 8

50 %

Question 9

re-esterification prefers which fatty acid?

Answer 9

palmitate

Question 10

what is the pathway of the chylomicron?

Answer 10

leave cell–>lymph–>blood–>liver

Question 11

some retinal is converted to retinoic (irreversible) instead of retinol. Where does this go?

Answer 11

the blood

Question 12

1 RAE = __ mcg retinol, ___ mcg beta carotene, __ mcg from b-carotene in supplements, ___ mcg from other provitamin carotenes

Answer 12

1; 12; 2; 24

Question 13

holo-RBP needs ___ to transport retinol to sites of action

Answer 13

TTR (transthyretin)

Question 14

zinc and amino acids are required to make and release this

Answer 14

apo-RBP

Question 15

foods fortified with retinol in Canada

Answer 15

margarine, low fat milk, soy beverages

Question 16

if the IU is from carotenes, to get RAE you divide by ___

Answer 16

20

Question 17

if all carotene, 1 RE = ___ RAE

Answer 17

0.5

Question 18

what is the DV of Vit A?

Answer 18

1000 RE

Question 19

what is rhodopsin?

Answer 19

11-cis retinal (made from retinol) and opsin

Question 20

xerophthalmia

Answer 20

dryness

Question 21

Bitot’s spots

Answer 21

foamy white spots of accumulated secretions

Question 22

keratomalacia

Answer 22

eye softens and becomes opaque

Question 23

The binding of retinoic acid to RXR and RAR promotes:

Answer 23

DNA transcription, which leads to cell differentiation and growth–>epithelial cells

Question 24

Consequences of too much retinol?

Answer 24

damage to bone and birth defects

Question 25

what is hyperkeratosis

Answer 25

obstruction and enlargement of hair follicles; this looks the same as vit. C deficiency

Question 26

This is the "final step" in vitamin A deficiency: the lens is covered so can't see, ability for making tears is lost. This is irreversible

Answer 26

Corneal ulceration

Question 27

what is a static indicator of vitamin A status?

Answer 27

plasma retinol, showing whether liver stores are depleted

Question 28

VAD is responsible for ___ child deaths in places with Vit A deficiencies

Answer 28

1/4

Question 29

Examples of secondary deficiency?

Answer 29

fat malabsorption, protein deficiency, zinc deficiency, infectious diseases

Question 30

What is the EAR?

Answer 30

amount that meets needs of 1/2 population

Question 31

what is the EAR based on for fat soluble vitamins?

Answer 31

maintaining sufficient liver stores, using factorial methods

Question 32

EAR for women is ___ and ___ for men; only difference based on weight

Answer 32

500 mcg RAE; 625 mcg RAE

Question 33

what is the efficiency of storage of ingested vit A?

Answer 33

about 40%

Question 34

what is the minimum acceptable reserve of vit A?

Answer 34

20 mcg/g in liver

Question 35

how is RDA found from EAR?

Answer 35

standard deviation = 20%

Question 36

what is RDA for women? What about for men?

Answer 36

700 mcg RAE; 900 mcg RAE

Question 37

acute toxicity is called:

Answer 37

hypervitaminosis A

Question 38

what is the UL?

Answer 38

3000 mcg RAE (based on liver damage, alopecia, bone pain, teratogenic effect)

Question 39

NOAEL is:

Answer 39

No observable adverse effect lvl (studies w/ high intentional intakes)

Question 40

LOAEL is:

Answer 40

lowest observable adverse effect lvl-->look at case reports

Question 41

hepatotoxicity is found at the LOAEL of ___ mcg

Answer 41

14000

Question 42

if IU from retinol, divide by ____ to get mcg RAE

Answer 42

3.3333

Question 43

if IU from b-carotene in a supplement, divide by ____ to get mcg b-carotene, then divide by ___

Answer 43

3.33; 2

Question 44

supplemental b-carotene is harmful to ____

Answer 44

smokers (around 10 mg)

Question 45

what is lycopene found in?

Answer 45

makes red colour in tomatoes

Question 46

what is lutein found in?

Answer 46

yellow veg/fruit, green leafy veg