Fat Soluble Vitamins Flashcards Preview

Nutrition > Fat Soluble Vitamins > Flashcards

Flashcards in Fat Soluble Vitamins Deck (39):
1

Retinal

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

2

Retinol

required for reproduction, utilized in testes/ovaries
can be made from retinal or retinyl esters in the liver

3

All trans retinoic acid

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

4

Vitamin A absorption

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

5

Vitamin A target tissues

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)

6

Vitamin A functions

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

7

Retinoic acid

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

8

Vitamin A DRI

females - 700 mcg/2333 IU
males - 900 mcg/3000 IU

9

Vitamin A testing

serum retinol
serum RBP

10

Vitamin A deficiency

primary = decr intake; secondary = lipid malabsorption

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

11

Vitamin A toxicity

> 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)

12

Vitamin A food sources:

retinol/retinyl esters

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

13

Vitamin A food sources:

Beta-carotene

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

14

Vitamin D active form

calcitriol
1,25-dihydroxycholecalciferol

15

Vitamin D metabolism

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

16

Vitamin D regulation

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

17

Vitamin D RDA

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

18

Vitamin D food sources

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

19

Vitamin D absorption

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

20

Vitamin D functions

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

21

Vitamin D functions (2)

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

22

Vitamin D deficiency

rickets (children) - inadequate calcification
osteomalacia (adults) - soft deformed bones, pain, weakness

23

Risks for vitamin D deficiency

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

24

Vitamin D excess/toxicity

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

25

Vitamin E RDA

15 mg/day
UL = 1000 mg

(1 IU = 0.66 mg of d-alpha-tocopherol and 0.45 mg of dl-alpha tocopherol))

26

Vitamin E absorption

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

27

Vitamin E functions

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

28

Vitamin E deficiency

assess via serum vitamin E

29

Vitamin E toxicity

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

30

Vitamin E food sources

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

31

Vitamin K forms

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

32

Vitamin K2

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

33

Vitamin K AI (adequate intake)

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

34

Vitamin K absorption

phylloquinones = easily absorbed via micelles
menaquinones = passive diffusion in lower GI

delivered via chylomicrons to:
lungs
kidneys
bone marrow
adrenal glands

35

Vitamin K functions

- 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)

36

Vitamin K functions (2)

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

37

Vitamin K excess

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

38

Vitamin K deficiency

reduced clotting time (easy bruising and bleeding)
osteoporosis

39

Vitamin K food sources

leafy greens
brassicas