Vitamins

Question 0

Water soluble vitamins

Answer 0

All except ADEK
Most precursors/coenzymes for intermediary metabolism
Found in vegetables
Deficiency within weeks (low stores)

B12 is weird in both these last points

Question 1

RDA

Answer 1

Does not reflect individual needs
Tool for comparing foods
Average…statistics…try to ensure everyone has adequate

Question 2

B1

Answer 2

aka thiamine -ATP> thiamine pyro-phos
-> carb metabolism (pyruvate dehydrog)

Deficiency -

• encephalopathy (ataxia, nystagmus) in EtOH abuse
• must administer with glucose to prevent Korsakoff’s (permanent)
• Beriberi - malnutrition -> peripheral neuropathy + dilated heart failure

Question 3

B2

Answer 3

aka riboflavin -ATP> FMN, FAD
-> redox cofactors

Deficiency -> fissuring of mouth, dry skin, purple tongue

Question 4

B3

Answer 4

aka Niacin -> NAD, NADP -> redox
Can also be synthesized from Tryp (not really essential)

Deficiency - Hartnup’s (low Tryp intake), carcinoid (uses up Tryp)
“Pellagra” - dermatitis (UV), diarrhea, dementia, death

Used clinically for dyslipidemia

Question 5

B5

Answer 5

Pantothenic acid -> part of Coenzyme A (carries acyl via thiol ester)
Deficiency not severe (other pathways?)

Question 6

B6

Answer 6

aka pyridoxine, pyridoxal, pyridoxamine, pyridoxal phos
(all interconverted) -> amino acid metabolism

Isoniazid (TB Rx) -> binds B6 -> functional deficiency

• > seizures
• always coadminister

Question 7

B7

Answer 7

aka Biotin
covalent -> Lys of enzymes -> carboxylation rx’s

Bound tightly by avidin (raw eggs) -> depression

Question 8

B9

Answer 8

aka Folate -> THF -> 1-carbon metabolism -> cell division (purines, thymidine)

Deficiency - lack of gut bacteria (produce folate), methotrexate (stops conversion to THF)
-> megaloblastic anemia
- rescue with leukovorin = THF
Prenatal - fetus needs high levels to prevent neural tube (bifida, anencephaly) - 1st trimester
- prenatal vitamins, fortified foods

Question 9

B12

Answer 9

aka Cobalamin
Weird: not found in plants (vegans!), large body stores (even longer than ADEK)

Methyl -> RBCs (folate trap) -> megaloblastic anemia
Deoxyadenosyl -> neural -> decreased vibration in b/l feet
Folate will fix/mask anemia -> permanent neuro damage
Deficiency - pernicious anemia - lack of intrinsic factor (autoimmune -> parietal cells)
- treat with IM B12 (bypasses intrinsic factor)

Question 10

Vitamin C

Answer 10

-> lysine, proline of collagen -> cross-links

Deficiency = scurvy -> bleeding, gums, joint pain, poor wound healing
Excess -> oxalic acid kidney stones

Question 11

Fat soluble vitamins

Answer 11

ADEK
Deficiency usually from fat malabsorption (ex surgery, pancreatic, small intestine)
Can get excess of A, D (long storage time - months)

Question 12

Vitamin A

Answer 12

Retinol -> reproduction
Retinoic acid -> epithelial - used as tx
cis-retinal -> rhodopsin (retinal pigment)

Found in plants (beta carotene) -> regulated conversion

Deficiency -> night blindness -> dry -> Bitot’s spots -> corneal ulceration -> keratomalacia (soft cornea)
Excess - teratogen, dry skin, liver damage, inc ICP

Question 13

Vitamin D

Answer 13

-> liver -> kidney -> 1,25(OH)D3 (aka calcitriol) -> Ca absorption

Deficiency (lactose intolerant, UV exposure, dark skin)
-> osteomalacia (pathologic fx’s), rickets in children (bowed)
Excess -> hypercalcemia (stones, bones, abdominal moans)

Question 14

Vitamin E

Answer 14

Protects lipid membranes

Deficiency -> disrupts RBCs

Question 15

Vitamin K

Answer 15

-> carboxylation of Glu -> clotting factors (ex PTT)

Produced by gut bacteria
Deficiency - premature infants or antibiotics (sterile gut) -> replace
Coumadin - blocks action -> reversible with Vitamin K