Fat Soluble Vitamins Table

Question 1

What is the function of Vitamin K?

Answer 1

Coagulation and carboxylation - cofactor for gamma-glutamyl carboxylase

Question 2

What is the source of Vitamin K in the diet?

Answer 2

Phylloquinone (leafy, green vegetables), menaquinones (fermentation in the gut, cheese), menadione (animal feed)

Question 3

What Pathologies are associated with Vitamin K deficiency?

Answer 3

Deficiency is rare. In infants, malabsorption – manifests as a coagulation disorder (increased PTT and bleeding)

Question 4

What toxicity is associated with Vitamin K?

Answer 4

None described, no TUL

Question 5

What should you know about coumadin and vitamin K?

Answer 5

Coumadin = Warfarin

Coumadin prevents regeneration of Vit K components

Question 6

Where is Vitamin K stored?

Answer 6

Cellular membranes

Question 7

What is the function of Vitamin A?

Answer 7

Prosthetic groups for opsin protein (important for vision); transcription regulator of RAR, RXR, PPAR – differentiation of goblet cells, prevention of keratinization, apoptosis of ca cells, maturation of DCs, recruitment of Ab secreting cells to gut; Carotenes act as antioxidants

Question 8

What is the source of Vitamin A in the diet?

Answer 8

Retinyl-acyl esters and carotenes found in red, yellow and orange fruits and vegetables

Question 9

What pathologies are associated with Vitamin A deficiency?

Answer 9

Anorexia, retarted growth, increased infections, alopecia, keratinization of epithelial cells, eye probe (night blindness, xerophthalmia, Bitot’s spots)

Question 10

What pathologies are associated with Vitamin A toxicity?

Answer 10

Toxicity = Hypervitaminosis A: TUL is 3,000 ug RAE/day – Nausea, vomiting, HA, desquamation of skin, alopecia, ataxia, liver damage, teratogenic

Question 11

How do you diagnose Vitamin A deficiencies/toxicities?

Answer 11

Relative Dose Response

Question 12

Where is Vitamin A stored?

Answer 12

Stellate cells in the liver

Question 13

What is the function of Vitamin D?

Answer 13

Most important: regulate Ca2+ homeostasis (increases Ca2+ uptake from gut, causes mobilization of bone Ca2+)
VDR – increases expression of Ca2+ transport proteins (TRPV6, calbindin, PMCA1b) and alters tight junction permeability (claudin)

Question 14

What is the source of Vitamin D in the diet?

Answer 14

Food of animal origin (liver, eggs, fatty fish), shitake mushrooms, fortified in diary products - dietary form is cholecalciferol

Question 15

What pathology is associated with Vitamin D deficiency?

Answer 15

Can be dietary, genetic, or absorption problem - rickets = seizures, growth retardation, failure of bone mineralization (osteomalacia)

Question 16

What pathology is associated with Vitamin D toxicity?

Answer 16

Most likely vitamin to have toxic effects; TUL is 4,000 IU – effect begin when serum Vit D is greater than 500 ng/mL, leads to calcification of soft tissue, hyperphosphatemia, HTN

Question 17

What is increased vitamin D associated with?

Answer 17

Reduced levels of colorectal cancer

Question 18

What can Vitamin D be synthesized from?

Answer 18

Can be synthesized de novo from cholesterol

Question 19

What is the main circulating form of Vitamin D in the blood?

Answer 19

25-OH D3 = main circulating form in blood, measured (liver)

Question 20

What is the biologically active form of Vitamin D?

Answer 20

1,25-OH D3 = biologically active (kidney)

Question 21

What is the Vitamin D precursor? Where is it located?

Answer 21

7-dehydrocholesterol = Vit D precursor from skin

Question 22

What is the function of Vitamin E?

Answer 22

Cellular oxidative stress defense - in lipid bilayers, IC, and plasma membranes.
Interactions: inhibits vitamin K absorption and metabolism; when oxidized, can be regenerated by ascorbate

Question 23

Where is Vitamin E found in the diet?

Answer 23

Tocopherols (saturated) and tocotrienols (polyunsaturated) - abundant in plant oils (palm, sunflower, canola), wheat germ

Question 24

What pathology is associated with Vitamin E deficiency?

Answer 24

Deficiency is rare, except in people with absorption problems (premies, Crohns, Short bowel syndrome) or inherited lipoprotein disorders – myopathy, hemolytic anemia, peripheral neuropathy, ataxia, loss of vibratory sense

Question 25

What pathology is associated with Vitamin E toxicity?

Answer 25

Not very toxic - TUL is 1,000 mg/d (very high)

Question 26

What can regenerate Vitamin E?

Answer 26

When oxidized, can be regenerated by ascorbate

Question 27

What type of Vitamin E does the liver export?

Answer 27

Liver will only export RRR stereoisomer