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PCL469 > Vitamins > Flashcards

Vitamins Flashcards

1
Q

DRI

A

Daily Reference Intakes

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2
Q

EAR

A

Estimated Average Requirement: daily nutrient intake estimated to meet req of 50% of healthy individuals in specific group

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3
Q

RDA/RDI

A

Recommended Daily Allowance/ intake:
Average Daily nutrient intake level estimated to meet the req of nearly all healthy individuals in a specific life stage or gender group = EAR*2 standard deviations

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4
Q

AI

A

Adequate intake: used when RDA is unknown

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5
Q

UL

A

Upper limit: in supplements: to pose no risks

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6
Q

Macronutrients

A

Proteins, Carbs, Fats. 56:130:14 g/d (RD/AI adults)

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7
Q

Micronutrients

A

Vitamins, minerals, trace elements
Individual RDA/AI

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8
Q

Vitamins def

A

Organic chem supplied exogenously to reach adequate functional amounts

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9
Q

Only non-exogenous vitamin

A

vitamin D

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10
Q

Fat-soluble vitamins

A

ADEK

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11
Q

Water soluble vitamins

A

C and B

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12
Q

Primary vs secondary vitamin deficiency

A

Primary: inadequate intake
Secondary: absorption and/or drug-nutrient interaction issues, increased requirements

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13
Q

Absorption of Fat-soluble vitamins + examples

A

bile salts enhance or are required, ex beta-carotene, vit A precursor
Reduced absorption with increased intake like Vit E

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14
Q

Transport of fat-soluble vitamins

A

vit E transported in blood by plasma beta-lipoproteins
Vit A and beta-carotene transported from intestine in chylomicrons via lymph
Vit A released into the plasma as retinol bound to RBP (ret binding protein)

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15
Q

Storage of fat-soluble vitamins

A

A and E mainly in liver, some in muscle, kidney, adipose tissue and lung
E mobilized slowly from adipocytes
vit K storage limited, depleted in 10-20 days

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16
Q

Vitamin A conversion pathway

A

beta-carotene –> retinal –> retinol (vit A)

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17
Q

beta-carotene vs retinols and retinals

A

Beta-carotene from plants, less easily absorbed than retinal and retinols
Retinols from animal products, like fish and dairy

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18
Q

RDA vitamin A

A

700 ug/d females
900 ug/d males
about 1 cup raw carrot

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19
Q

vitamin A functions

A
  1. cellular differentiation - immunity development
  2. visual pigments - opsin binds retinal = rhodopsin
  3. Regulation of gene expression via retinoic acid
    all-trans retinoic acid binds to RAR, RAR+RXR binds RARE
    RAR- retinoic acid receptor RXR = retinoid X receptor
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20
Q

Vitamin A deficiency

A
  • leading cause of blindness in developing nations = dietary deficiency
  • increase infectious diseases, resp, GI
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21
Q

Vit A: pharma uses

A
  • skin conditions, acne, fine lines, blemishes
  • acute promyelocytic leukemia (RAR mutations, impaired diff of promyelocytes (PCL302))
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22
Q

Vitamin A toxicity: reason, acute effects, long-term toxicity

A
  1. Results from excess supplementations
  2. Acute effects of 1 dose 200 000 mcg: blurred vision, vertigo, nausea
  3. Long-term toxicity: liver damage, birth defects, skin + joint damage
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23
Q

Vitamin E; 2 types, how many subtypes each has

A

Four tocopherols, and four tocotrienols (alpha, beta, gamma, delta), sat vs unsat side chain

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24
Q

Vit E with highest nutrient significance, where found

A

Alpha-tocopherol- greatest nutritional significance
plant source: veggie oils, wheat ger,

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25
Q

Vitamin E: highest bio activity

A

d-alpha-tocopherol

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26
Q

RDA of Vit E

A

RDA 15 mg/d, alpha-tocopherol
100 ml canola oil, 15 tbsp wheat germ

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27
Q

Vitamin E functions

A
  • antioxidant
  • prevents lipid oxidative damage
  • inhibits PKC, cell signalling
  • inhibits platelet aggregation
  • enhance vasodilation
  • Affects activity of immune + inflammatory cells
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28
Q

Prevalence of vitamin E deficiency

A

Rare in healthy adults

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29
Q

Reason for vit E deficiency

A
  • chronic fat malabsorption or beta-lipoprotein deficiency
  • premature infants - limited storage, absorption
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30
Q

Symptoms of vit E deficiency

A
  • Anemia - reduced erythrocyte survival
  • Progressive neurological disorder - impaired balance + neuropathy
31
Q

Vit E: absorption, circulation, storage

A
  1. 50% absorption
  2. Circulates bound to beta-lipoprotein
  3. Storage: liver, muscle and fat
32
Q

Therapeutic use/prevention

A

Treatment of susceptible individuals - preventing CVD

33
Q

Range of vit E toxicity

A

Limited, when >2000 mg alpha-tocopherol/day

34
Q

Toxicity of vitamin E

A
  • May exacerbate a vitamin K deficiency
  • Possiblity of impaired blood clotting - hemorrhage
35
Q

Vitamin E downreagulates these drugs:

A

Anticoagulant therapy, antiplatelet drugs, vitamin K deficient individuals

36
Q

These drugs downregulate vitamin E absorption :

A

cholestryamine
colestipol
isoniazid
mineral oil
phenobarbital
phenytoin
carbamazepine

37
Q

Natural occurring vitamin K

A

plants: phylloquinone K1
bacteria: menaquinone-n K2

38
Q

dietary sources of vitamin K

A

K1: green leafy veggies
K2: egg yolk, fermented food, microbiota

39
Q

RDA vitamin K

A

90 mcg, 1/2 cup cooked kale - 530 ug

40
Q

Vitamin K epoxide cycle

A

Vit K –> Reduced vitamin K, Hydroquinone –> Vitamin K epoxide –> vit K

41
Q

Enzyme quinone reductase

A

vitamin K –> reduced vit K, Hydroquinone

42
Q

Carboxylase

A

HYdroquinone –> vit K epoxide
also produces gamma -carboxylated proteins
clotting factors
matrix gla proteins MGP

43
Q

what does matrix gla protein do?

A

inhibition of innapropriate calcification/mineralization when not in skeletal tissue, both MGP + K need carboxylation to properly work

44
Q

Epoxide reductase

A

Vitamin K epoxide –> vitamin K, recycling step

45
Q

Vit K epoxide enzymes inhibited by warfarin

A

Quinone reductase, Epoxide reductase, if want low clotting, anticoagulation

46
Q

Calcification in bone vs prevention of calcification in arteries

A

in bone - vitamin K, but prevent calc. in arteries - MGP, still need preventing surplus of K

47
Q

Vitamin K functions

A

Coagulation, calcium-binding of some proteins, bone mineralization, cellular growth and regulation

48
Q

Vitamin K dependent clotting factors where, coenzyme for what, conversions?

A

Synthesized in the liver, coenzymes for the gamma-carboxylation of glutamin acid residues
result in conversion to gamma-carboxyglutamic acid

49
Q

Vit K storage, recycling

A

Limited storage 10-20 days
reused by oxidation/red cycle

50
Q

What produces Vit K deficiency

A

Malabsorption
Administration of antagonist warfarin
chronic use cephalosporin antibiotics

51
Q

Vit K deficiency symptoms

A

Increased prothrombin time - bleeding, hemorrhagic disease of the newborn
first evident in GI bleeding

52
Q

Therapeutic uses of vit K

A

increase biosynthesis of liver clotting factors
prevention of hemorrhagic disease of newborn
antidote for anticoagulant toxicity

53
Q

Vitamin D, how is it different

A

not a true vitamin - can be synthesized by body

54
Q

Derivation of vit D

A

from cholesterol
D2 from plants - ergocalciferol
D3 from animals - cholecalciferol

55
Q

Vitamin D regulation of gene transcription

A

calcitriol + VDR complex in nucleus
Complex binds with RXR to form heterodimer
binds to vitamin D responsive elements
Change in gene transcription
(bone related genes, 24 hydroxylase, p21, TGFbeta2 and others)

56
Q

Vitamin D synthesis in body

A

7-dehydrocholesterol + UVB in skin converted to
Cholecalciferol vit D in liver converted to
Calcidiol 25-hydroxyvitamin D3 in kidney conv to
Calcitriol 1,25 dihydroxyvitamin D
^^ active form - bone + small intestine

57
Q

Vitamin D actions

A
  • increase calcium absorption from gut
  • increase bone mineralization
  • regulation of immune function
58
Q

When lack of UVB Toronto and Edmonton to make it D

A

Latitude 43.6 N - Toronto: Nov-Feb
Latitude 53 N - Edmonton - Oct-March

59
Q

Vitamin D insufficiency definition

A

Conservative <40 nmol/L lack of 25 (OH)-D, the calcidiol in the kidney- easier, higher to measure in blood
No stimulation of PTH when < 80 nmol/L

60
Q

Vitamin D deficiency in children

A

Rickets: Insufficiency or mutations in VDR

61
Q

Vit D deficiency in adults

A

Osteomalactia: rare, decrease in bone mineral [], bone pain and soft bones

62
Q

Toxicity of vitamin D from what

A

from chronic high dose supplementation
higher potential with supplemented calcitriol

63
Q

Reason for adverse effect of vit D

A

Adverse effects from elevated blood calcium levels

64
Q

Symptoms of vit D toxicity

A

Fatigue, headache, diarrhea, hypercalcemia
demineralization of bone and calcification of organs such as heart, kidneys, lungs, blood vessels and skin, growth arrest
too low - low mineralization
too much - remove mineralization as well

65
Q

Vitamin D bioregulation when low Ca++

A

Low ca –> parathyroid gland–> increase PTD –> increase Ca++ reabsorption and PO4 excretion in kidneys
Increase calcitriol from kidney–> Ca++ reabsorption from intestine
PTH –> Higher CA++ PO4+ release from bone
Result normal Ca++

66
Q

What does PTH do?

A

Stimulate hydroxylases

67
Q

Normal range calcium extracellular

A

2.2-2.7 mM

68
Q

Hypocalcemia: symptoms

A

<2.05 mM
Symptoms;
related to increased neuromuscular irritability
numbness, tingling in fingers, toes
muscle cramps, tetany, convulsions
irritability, impaired mental capacity
Laryngospasm, bronchospasm, cardiac arrest

69
Q

Hypocalcemia: causes

A

Hypoparathyroidism
Vitamin D deficiency
Vitamin D resistance

70
Q

Hypercalcemia symptoms

A

> 2.96 mM
Symptoms:
Decreased neuromuscular activity
Lethargy, lack of concentration, sleepiness
Headache, muscle weakness
Vomiting, diarrhea, polyuria, nocturia

71
Q

Hypercalcemia Causes

A

Hyperparathyroidism
Malignancies
Ectopic vitamin D production

72
Q

Vitamin D therapy

A

Ergocalciferol vitamin D2
Calciferol
Drisdol (ergocalciferol) 25 hydroxyvitamin D2
Calcitriol 1.25 dihydroxyvitamin D3

73
Q

Considerations for therapy with vitamin D

A

Time to reach equilibrium
Fat malabsorption, hepatobiliary disease or renal disease

74
Q

Drug interactions with vitamin D

A

Anticonvulsants: inhibit hydroxylation in liver
Glucocorticoids: inhibit actions of vitamin D at the VDR

PCL469 (6 decks)

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