Fat-Soluble Vitamins

Question 1

• A, D, E, K
• Carried to brush border of intestine by micelles for simple diffusion through membrane
• Chylomicrons contain fat-soluble vitamins and transport them via lymph to bloodstream to liver
• Stored in liver and fatty tissues
• Long storage time and slow excretion leads to risk of toxicity in excess

Answer 1

Fat soluble Vitamins

Question 2

• Exists as retinol, retinal, retinoic acid
• Contains a beta-ionone ring
• Stored in liver as retinyl palmitate
• Liver releases this vitamin as retinol bound to Retinol-Binding Protein (RBP)
• RBP interacts with transthyretin to prevent renal filtration
• RBP interacts with specific receptors over target tissue to release retinol into cell
• Used in treatment of psoriasis, promyelocytic leukemia, and acne

Answer 2

Vitamin A

Question 3

• Alcohol form of Vit A
• Functions in reproduction process
• A primary alcohol with a beta-ionone ring attached with unsaturated fatty acid side chain, found in animal tissue as retinyl ester with long chain fatty acids.

Answer 3

Retinol

Question 4

• Aldehyde form of Vit A
• Functions in vision process
• Aldehyde obtained by oxidation of retinol, it can be converted to retinol.
• Converted to 11-cis-retinal for vision process
• 11-cis-retinal combines with opsin to creat rhodopsin… light breaks the bond to opsin and all-trans retinal
• all-trans retinal is converted to all-trans retinol and converted back to 11-cis-retinal in retinal pigment epithelium

Answer 4

Retinal

Question 5

• Acidic form of Vit A
• Functions in cell morphogenesis, growth and differentiation
• Acidic derivative of retinal through oxidation of aldehyde group, it cannot give rise to retinal or retinol as it cannot be reduced in the body.
• Acts as steroid hormone interacting with RXR and/or RAR dimer which then binds to chromatin of RARE activating its specific gene transcription

Answer 5

Retinoic Acid

Question 6

• carotenoid in the food, it has provitamin A activity.
• abundantly present in plant foods and can yield two molecules of retinal in intestine, though not as efficient source as retinal
• Cleaved by intestinal beta-carotene 15-15’ Dioxygenase into two retinal

Answer 6

Beta-Carotene

Question 7

• seen in Vitamin A Deficiency
• Night blindness
• Conjunctival xerosis (dryness) with Bitot’s spots (white patches of keratinized epithelium appearing on the sclera)
• Rare blinding corneal ulceration and necrosis

Answer 7

Xerophthalmia

Question 8

• seen in Vitamin A Deficiency
• Softening of cornea leads to corneal scarring that blinds at least a quarter million children each year (4-25% fatality rate due to infections)

Answer 8

Keratomalacia

Question 9

-increased intracranial pressure, vertigo, diplopia, bulging fontanels in children, seizures, exfoliate dermatitis, and may result in death

Answer 9

Hypervitaminosis A (Acute Toxicity)

Question 10

-dry skin, cheilosis, glossitis, vomiting, alopecia, bone demineralization and pain, hypercalcemia, lymph node enlargement, hyperlipidemia, amenorrhea, hepatoslpenomegaly, features of pseudotumor cerebri with increased intracranial pressure of papilledema

Answer 10

Hypervitaminosis A (Chronic Toxicity)

Question 11

• Active form of this vitamin is 1,25-dihydroxylcholecalciferol
• This vitamin regulates plasma calcium and phosphorus levels
• Regulates osteoblastic and osteoclastic activity and inhibits transcription of PTH

Answer 11

Vitamin D

Question 12

• induced by 1,25(OH)2D3

- helps in calcium and phosphate absorption in intestine

Answer 12

Calbindin

Question 13

• Result from deficient production of this vitamin in the skin, lack of dietary intake, accelerated losses of the vitamin, impaired activation of vitamin, or resistance to biologic effects of active vitamin
• May result in hypocalcemia, secondary hyperparathyroidism, impaired mineralization of the skeleton and proximal myopathy
• Most common cause of rickets and osteomalacia

Answer 13

Vitamin D Deficiency

Question 14

• seen in Vitamin D deficiency
• Growth retardation associated with expansion of the hypertrophic chondrocyte layer of growth plate
• Hypophosphatemia (consequence of secondary hyperparathyroidism)
• Signs include: bone deformities (bow legs, knock knees, pigeon chest, rib beading, teeth formation), swelling and pain in the joints, decreased serum calcium and phosphate levels, increased alkaline phosphatase

Answer 14

Rickets

Question 15

• Exists as 4 different isoforms for tocopherol (alpha, beta, gamma, delta)
• Antioxidants
• Stored in fat deposits and transported through VLDL
• Prevent oxidation of LDL and reduce risk of cardiovascular disease
• Stabalize ubiquinone during cellular respiration
• Enhance heme synthesis
• Maintain normal immune mechanism

Answer 15

Vitamin E

Question 16

Most potent scavenger of reactive oxygen species

Answer 16

Alpha Tocopherol

Question 17

Potent scavenger of reactive nitrogen species

Answer 17

Gamma Tocopherol

Question 18

• Does not exist as dietary deficiency
• Seen in severe and prolonged fat malabsorptive diseases
• Manifestations: peripheral neuropathy, hemolytic anemia, skeletal myopathy, degeneration of myelinated axons
• Can potentiate the effects of blood thinning medications

Answer 18

Vitamin E Deficiency

Question 19

• Two forms
• Dietary sources: green leafy vegetables, oils
• Functions: Posttranslational carboxylation of glutamic acid, which is necessary for calcium binding to gamma-carboxylated proteins such as prothrombin (factor II);factors VII, IX, and X; protein C; protein S; osteocalcin; vascular smooth muscle
• Warfarin blocks the conversion of this vitamin into active form

Answer 19

Vitamin K

Question 20

• cause for Hemorrhagic disease of newborns
  a) low fat stores
  b) low breast milk levels of this vitamin
  c) sterility of infantile intestinal tract
  d) liver immaturity
  e) poor placental transport
  f) Symptoms: 1-7 days after birth, bleeding intracranially, gastrointestinally, skin
  g) all newborns given 1 mg IM of this vitamin
• Other causes of this Vitamin Deficiencies
  a) cystic fibrosis
  b) celiac disease and Crohn’s disease
  c) obstructed biliary tracts
  d) small bowel resection
  e) prolonged broad spectrum antibiotic treatment

Answer 20

Vitamin K Deficiency

Question 21

• deficiency is endemic where diets are chronically poor (Southern Asia, Sub-Saharan Africa, Latin America, Western Pacific, China) and results in xerophthalmia.
• milder stages of night blindness and conjunctival xerosis with Bitot’s spots as well as rare, potentially blinding corneal ulceration and necrosis.
• Keratomalacia leads to corneal scarring that blinds at least a quarter of a million of children each year
• deficiency poses an increased risk of mortality from diarrhea, dysentery, measles, and respiratory disease.
• deficiency can compromise barrier and innate and acquired immune defenses to infection.
• goose flesh appearance

Answer 21

Vitamin A Deficiency

Question 22

What are the 2 forms of Vitamin K?

Answer 22

• Vitamin K1 (phylloquinone - veggie and animal source)

- Vitamin K2 (menaquinone - synthesized by bacterial flora)

Question 23

Which form of vitamin D do you get from plants?

Answer 23

Vitamin D2 (ergocalciferol)

Question 24

Which form of vitamin D do you get from animal tissues and endogensous from skin cells synthesizing light?

Answer 24

Vitamin D3 (cholecalciferol)

Question 25

form of vitamin A that functions in reproductive process?

Answer 25

retinol

Question 26

form of vitamin A that functions in vision process?

Answer 26

retinal

Question 27

form of vitamin A that functions in cell morphogenesis, growth, and differentiation?

Answer 27

retinoic acid

Question 28

what kind of activity does b-carotene have?

Answer 28

provitamin A activity

Question 29

cholecalciferol = ?

Answer 29

vit d3

Question 30

ergocalciferol = ?

Answer 30

vit d2

Question 31

what is useful in the treatment of promyelocytic leukemia?

Answer 31

Retinoic acid

Question 32

Which vitamin is required for the post translational carboxylation of glutamic acid which is necessary for calcium binding to gamma carboxylated proteins such as prothrombin?

Answer 32

Vitamin k

Question 33

Which two fat-soluble vitamins do not cross placenta membranes well

Answer 33

E and K