Fat soluble vitamins

Question 1

Vit A (3 fxns)

Answer 1

1) Essential in photochemical basis of vision (signals in retina –> brain visual cortex
2) Maintenance of conjunctival membranes & cornea
3) Critical for epithelial cellular differentiation and proliferation

Question 2

Vit A (RDA/foods/eval)

Answer 2

RDA: 900 ug/d (or 1800 ug/d beta carotene)
Foods: Preformed: liver, dairy, egg yolks, fish oil
Precursor: (carotenids/BC): yellow/orange and green veg
Eval: serum retinol

Question 3

Vit A (defic/toxic)

Answer 3

Defic: 1) night blindness, xerophthalmia (dryness of cornea –> corneal ulcers and blindness) “Bitot’s spots”
2) immune defic (supplementing vit A defic decr child mortality 23-34%)
3) abnormal epithelial morph
4) can be used to treat measles
Tox: 1) ONLY with Vit A (does dependent)
2) vomiting, increased ICP, HA, bone pain, bone mineral loss, birth defects

Question 4

Vit A (3 risks for defic)

Answer 4

Low intake or low fat intake (

Question 5

Vit D (4 fxn)

Answer 5

Acts as a hormone to:

1) Maintain intra/extracellular Ca
2) Stimulates intestinal absorption and renal reabsorption of Ca and P (also mobilizes both from bone)
3) Innate immune fxn (generation of toxic radicals)
4) Cellular GROWTH and DIFFERENTIATION through nuclear and plasma membrane vit D receptors

Question 6

Vit D (metab)

Answer 6

Absorbed by chylomicrons
Precursor dehydrocholesterol in skin CONVERTED to CHOLECALCIFEROL (vit D3) by UV light
Vit D2 or D3 hydroxylated in liver to 25-OH-C then actviated to 1,25-dihydroxy-C in kidney

Question 7

Vit D (RDA/foods/eval)

Answer 7

RDA: 600 IU/d (70 yo, Limit 4000
SUPPLEMENT: 400 IU D3 for breastfed infants
UVB tanning and sun exposure (5-15 min) NOT recommended by derm
Food: Fish over oils, fatty fish, egg yolk, fortified milk andn formulas [D3 from animals, D2 ergocalciferol from plants)
Eval: Serum 25(OH) Vit D levels

Question 8

Vit D Defic (levels/hypervitainosis risk/toxicity levels)

Answer 8

Defic: 25 OH-D 30
CLASSIC TRIAD in serum: low C + lw P + high alk phos
Risk of hypervitaminosis with CHRONIS GRANULATOUS DZ (eg sarcoidosis)
Toxicity: >10000 IU/d for weeks, causes hypercalcmeia, vomtiing, seziures, soft tissue calcification and nephrocalcinosis

Question 9

Vit D (7 risks for defic)

Answer 9

Lack of sun
Low intake
Fat malabsorption
Breastfed (esp if mother defic)
Dark skin
Obesity
Liver/renal dz

Question 10

Vit E (2 fxns)

Answer 10

Antioxidant (free radical scavenger)

Cell membrane stabilizer

Question 11

Vit E (source)

Answer 11

Polyunsaturated vegetable oils, wheat germ

Question 12

Vit E (defic/toxciity)

Answer 12

Defic: neurologic degeneration (DTRs, reflex probs, spinocerebellar ataxia and HEMOLYTIC ANEMIA
Toxic: Low risk: coagulopathy (v large does inhibit Vit K dependent factors
MEGAdoses for protection against heart dz? NO!

Question 13

Vit E (2 risks for defic)

Answer 13

Prematurity

Fat malabsorption: short gut, CF

Question 14

Vit K (fxn)

Answer 14

Carboxylation of coag proteins (factors 1972) 10, 9, 7, 2

Question 15

Vit K (levels/foods)

Answer 15

All newborns should receive single IM dose on 0.5-10.0 mg (to prevent hemorrhagic dz of the newborn) can’t be given orally
Foods: leafy veg, fruits, seeds, synthesized by INTESTINAL BACTERIA

Question 16

Vit K (defic)

Answer 16

Prolonged coag times, hemorrhagic dz of newborn, Bleeding into: skin (purpura), GI tract, CNS

Question 17

Vit K (2 risks for defic)

Answer 17

Newborns

Late (2-12 weeks) esp breastfed infants or fat malabsorption/chronic ABX use