Fat Soluble Vitamins

Question 1

What are sources for Vitamin A?

Answer 1

Liver, eggs, whole milk, butter

Beta carotene from carrots and sweet potatoes

Question 2

What are effects of Vitamin A toxicity?

Answer 2

Hypervitaminosis A
Membrane lysis and tissue damage
Excessive dryness of skin, desquamation, alopecia
Hepatomegaly, Cirrhosis
Pseudotumor cerebri (headache, nausea, ataxia)
Thickening of long bones, hypercalemia, calcification of long bones
Teratogenicity

Question 3

What is another name for Vitamin D2 and D3?

Answer 3

D3 is cholecalciferol, D2 is ergocalciferol

Question 4

Where is Cholecalciferol derived?

Answer 4

Vit D3 is formed in the skin from 7 dehydrocholesterol when exposed to sunlight. Other sources include fatty fish, liver, egg yolk

Question 5

Where does activation of Vit D occur and what is the product?

Answer 5

It occurs in the liver and kidney. The product is calcitriol or 1,25 dihydroxyvitamin D

Question 6

What are sources of tocopherols and tocotrienols?

Answer 6

Vegetable oil, liver and eggs

Question 7

What are results of tocopherol deficiency?

Answer 7

Nerve and muscle membrane damage

Question 8

What are sources of phylloquinone?

Answer 8

Green vegetables

Question 9

What are sources for menaquinone and menadione?

Answer 9

Menaquinone in synthesized by intestinal bacteria, Menadione is a synthetic compound

Question 10

What are sources of thiamine?

Answer 10

Pork, fish, seafood, beef, yoghurt, fortified rice, cereals, beef and flour

Question 11

Thiamine is a coenzyme for which enzymes?

Answer 11

Pyruvate dehydrogenase, a ketoglutarate dehydrogenase, branched chain amino acid dehydrogenase, transketolase

Question 12

What are clinical entities that arise from thiamine deficiency?

Answer 12

Infantile beriberi - tachycardia, vomiting, seizures and death
Adult beriberi- dry skin, irritability, disordered thinking, progressive paralysis
Wernicke encephalopathy - confusion, ataxia, nystagmus, ophtalmoplegia
Korsakoff - amnesia, confabulation, hallucinations

Question 13

Vit B2 is derived from what sources?

Answer 13

Milk and eggs

Question 14

What are symptoms of Vit B2 deficiency?

Answer 14

Seborrheic dermatitis, cheilosis, angular stomatitis, desquamation and inflammation of the tongue

Question 15

What is the amino acid precursor for Vitamin B3?

Answer 15

Tryptophan is the precursor for niacin, and requires pyridoxine

Question 16

What are sources of niacin?

Answer 16

Grains, cereal, milk, lean meat and liver

Question 17

TRUE OR FALSE

The etiologies for niacin deficiency include isoniazide use

Answer 17

TRUE. Etiologies of pellagra (diarrhea, dermatitis, dementia) include corn based diet, hartnup disease, carcinoid syndrome, isoniazid disease

Question 18

What is the active form of Vitamin B 5?

Answer 18

The active form of pyridoxine is pyridoxal 5 phosphate

Question 19

What are sources of pyridoxine?

Answer 19

Potatoes and other starchy vegetables, Non citrus fruits, pyridoxal from pyridoxamine from meat

Question 20

Pyridoxine is the coenzyme for what reactions

Answer 20

Transamination of amino acids
Decarboxylation of glutamate and histidine, ala synthase, crystathionine synthase, synthesis od niacin from tryptophan, glycogen phosphorylase

Question 21

What is the only water soluble vitamin with significant toxicity?

Answer 21

Pyridoxine causing sensory neuropathh

Question 22

What are sources of Vitamin B12?

Answer 22

Sources for cobalamin include

Liver, whole milk, eggs, oysters, shrimp, pork, chicken

Question 23

Vitamin B12 is the coenzyme for which enzymes?

Answer 23

Methionine synthase and methylmalonyl coA mutase

Question 24

Ascorbic acid is the coenzyme for what enzymes?

Answer 24

Copper and iron containing hydroxylases such as

Proline and lysine hydroxylases in collagen, dopamine beta hydroxylase

Question 25

What inhibits absorption of Vitamin H?

Answer 25

Avidin in egg whites inhibits absorption of Vitamin H or Biotin

Question 26

Vitamin H is the conezyme for which enzymes?

Answer 26

Pyruvate Carboxylase
Acetyl coA carboxylase
Propionyl coA carboxylase

Question 27

What are the specific tests for vitamin deficiencies

Answer 27

Vitamin B1 - erythrocyte transketolase activity assay
Vitamin B6 - erythrocyte transaminase assay
Vitamin B12 - Schilling test, Methylmalonic acid test
Folate - Formiminoglutamic acid excretion test