Vit A

Question 1

Sources

Answer 1

Preformed
-Retinoids (retinal, retinol, retionic acid)
- Found in animals product
Provitamins
-Must be converted to retinoids, found in plants

Question 2

Retinoids

Answer 2

Retinol- alcohol
Retinal-aldehyde
Retinoid acid- derived form retinal
Retinyl ester- esterified w/FA

Question 3

Digestion

Answer 3

released from protein/fa
*protein=stomach, pepsin
*FA= SI, pancreatic enzyme
incorporated into micelles

Question 4

Absorption

Answer 4

in proximal SI
*70-90% of retinoids
*20%-50% of cartenoids
Storage in liver
RBC transport in serum

Question 5

Functions

Answer 5

Night vision
mucus production in eyes
generates pigments for the retina
cell division
growth-retoic acid
*embryo, genes, bone, lungs, treachea, skin and cornea
healthy skin (topical meds= birth defects)
regulate immune system = t-lymphocytes phagocytes

Question 6

Function in rods and cones

Answer 6

Cones= bright light, color vision 
Rods= dim light, black and white
* B-carotene
-prevention of CVD
-cancer prevention 
-age degeneration 
-cataracts

Question 7

RDA

Answer 7

900 mcg
700 mcg
RAE- 1 mg of retinol= 12 mg B-carotene
UL=3,000 mcg/d (10,000/mcg)= 24 mg carotenoid

Question 8

Deficiency

Answer 8

• night blindness - impaired production of rhodopsin
• xerophthalmia-dryness of cornea, reversible
• corneal ulceration/keratomalcia/blind soft cornea, irriversible
• hyperkeratosis-keratinized cells replace epithelial cells , hair follicles plugged, bumpy, dry skin
• impaired immunity- decreased resistance to infections

Question 9

Population at risk

Answer 9

young children
urban poor
older adults
alcoholism
liver disease
fat malaborption

Question 10

Tox

Answer 10

none from carotenoids

• preformed A=inevitable-storage cont. until toxicity develops
  1) acute- short term, symptoms disappear, when intake steps: GI, headache, blurred vision, poor muscle coordination
  2) chronic- long term, possibly permanent: bone muscle pain, skin disorder, no apetite, headache, fatigue, dry skin, increased liver size, vomiting
  3) tertongenic effect-3x RDA, physical defect on fetus

Question 11

Assessment

Answer 11

clinical-
measure of dark adaptation
-rhodopsin regeneration rate
-CIC
-plasma retinol conc. change in plasma conc. before and after 5 hrs of oral med of RE in oils