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Nutri Sci > Fat Soluble Vitamins > Flashcards

Fat Soluble Vitamins Flashcards

1
Q

Fat soluble vitamins

A

Lipid soluble
in the presence of fat
Absorption and transport is similar to fat
Can be stored
Can be toxic in high doses

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2
Q

Vitamin E

A

Alpha tocopherol

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3
Q

Vitamin E Function

A

Antioxidant
Protect unsaturated FA

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4
Q

Vitamin E Absorption and transport

A

Emulsion with bile acids
Incorporate into chylomicrons for circulation
Processed in the liver

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5
Q

Vitamin E Storage and excretion

A

Excrete via bile and feces
Can excrete in urine after processing in liver

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6
Q

Vitamin E deficiency

A

Rare
Result of insufficient fat absorption
Linked to maintenance of cell membranes

Erythrocyte hemolysis

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7
Q

Vitamin E deficiency symptoms

A

Retinopathy
Peripheral neuropathy
Ataxia
Lower immune function

Erythrocyte hemolysis
(breakdown of RBC)

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8
Q

Vitamin E food sources

A

Widely available
Vegetable oils
Destroyed by heat and oxidation

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9
Q

Vitamin E toxicity

A

Interference with blood clotting
Rare

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10
Q

Vitamin A

A

Retinoids

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11
Q

Vitamin A Function

A

Required to form rhodopsin in the rod cell photoreceptors

Regulation of gene expression

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12
Q

Vitamin A sources

A

Preformed and dietary sources

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13
Q

Vitamin A pre formed sources

A

Animal products
Liver
Dairy
Egg
Fish
Fortified foods

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14
Q

Vitamin A dietary sources

A

Beta carotene
Sweet potatoes
Carrots

Alpha carotene
Beta cryptoxanthin

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15
Q

Conversion of pro vitamins

A

Requires BCO1
Converts beta carotene into retinal
Not perfect efficiency
Depends on bioavailability

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16
Q

Vitamin A absorption and transport

A

Vitamin A as retinyl esters
Absorbed in SI
Need dietary fat and bile acids
Must be de-esterified to be absorbed
De-esterify → absorb → esterify → chylomicrons → circulate

Vitamin A as pro vitamin A
Lower absorption
Processing can increase absorption
Still requires dietary fat

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17
Q

Vitamin A after absorption

A

Metabolized in enterocytes before entering bloodstream

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18
Q

Vitamin A interconversion

A

Retinyl esters ←→ retinol ←→ retinal ←→ retinoic acid
Beta carotene converted to retinal
Retinoic acid = active form

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19
Q

Vitamin A transport and storage

A

Retinyl esters can be stored in hepatic stellate cells
Retinol binds to retinol binding protein
Forms holo RBP
Deliver retinol to other tissues

Excrete in bile and kidneys

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20
Q

Vitamin A RDA

A

In retinol activity equivalents
Higher for pregnancy and lactating

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21
Q

Vitamin A deficiency

A

Night blindness
Xerophthalmia (dryness)
Bitot spots
Poor growth
Increased susceptibility to infection

22
Q

Vitamin A toxicity

A

Acute and chronic

23
Q

Vitamin A toxicity - acute

A

Single excessive dose
Nausea
Headache
Double vision
Vomiting

24
Q

Vitamin A toxicity - chronic

A

3-4 x RDA
Anorexia
Hair loss
Skin problems
Increased bone fractures
Eye pain
Liver damage
Birth defects

25
Q

Vitamin K

A

Phylloquinone

26
Q

Vitamin K function

A

Blood clotting
Essential for activation of proteins that participate in clotting process
Bone calcification

27
Q

Gamma carboxylation

A

Clotting factors require Ca binding to be active
Gamma carboxylation provides this ability
Adds carboxylic acid group to glutamate → allow for Ca binding

28
Q

Vitamin K drug interaction

A

Blood thinner
Warfarin interfere with recycling of vitamin K
Makes it less available, reduce gamma carboxylation

29
Q

Vitamin K transport, absorption

A

Absorbed in SI
Requires fat, bile acids
Supplements are more bioavailable
Transported in chylomicrons

30
Q

Vitamin K storage, transport

A

Limited storage
Use reducing power (Nadph) to recycle

31
Q

Vitamin K RDA

A

No UL, toxicity
Interfere with anticoagulants

32
Q

Vitamin K deficiency

A

Primary deficiency is rare

Secondary deficiency
Malabsorption
Anticoagulants

Hemmorages

33
Q

Vitamin K food souces

A

Green, leafy veg
Gut bacteria

34
Q

Vitamin D food sources

A

Animal products
Liver
Beef
Veal
Eggs

Sun contact

Fortified foods
Milk
OJ
Breads

35
Q

Vitamin D absorption

A

About 50% efficient
Occurs in SI
Incorporated into micelles
Packaged into chylomicrons to circulate
Circulates bound to vitamin D binding protein

36
Q

Vitamin D activation

A

Two step activation
Liver (add OH)
Kidneys (add OH)
Final product = calcitriol, active vitamin D

37
Q

Vitamin D synthesis factors

A

Amount of radiation
Age
Race
Clothing
Sunscreen

38
Q

calcitriol, active vitamin D

A

Regulates its own breakdown via negative feedback
Made where it is used
Potent gene expression regulator

39
Q

Vitamin D function

A

Maintain serum calcium/phosphorus levels

Behaves as a hormone

Immune system

Bone health

40
Q

Low Ca 2+ levels

A

PTH released from parathyroid gland

PTH activates enzymes in kidney that convert vitamin D to active form

PTH and active vitamin D demineralize bone to release calcium and phosphorus into blood

Active vitamin D increases calcium absorption from intestine and reabsorption from kidneys

41
Q

High Ca 2+ levels

A

Calcitonin released from thyroid
Stimulate addition of Ca and phosphorus to build bone

42
Q

Vitamin D hormone

A

Regulates gene expression by binding to vitamin D receptor
Nuclear receptor has broad functions

43
Q

Vitamin D immune system

A

Influence immune response and host defense against pathogens

44
Q

Vitamin D bone health

A

Calcitriol facilitate calcium absorption from gut
Increase expression of calbindin and calcium channels
Similar effects on renal tubules

45
Q

Vitamin D recommendations

A

Older adults need more
15 mins of sunlight a day

46
Q

Vitamin D deficiency

A

Inadequate calcium and phosphorus deposition in bone

Osteomalacia
Rickets

47
Q

Osteomalacia

A

Soft bones
In adults

Caused by kidney/stomach/gallbladder/intestinal/liver disease affecting vitamin D metabolism/absorption

48
Q

Rickets

A

In kids
Bowed legs
Enlarged head and rib cage
Deformed pelvis

49
Q

Vitamin D toxicity

A

Nearly impossible
Results from excess supplementation

50
Q

Vitamin D toxicity symptoms

A

Hypercalcemia
(Calcification of tissues)

Kidney dysfunction
Loss of appetite
GI stress

Nutri Sci (10 decks)

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