Water Soluble Vitamins Flashcards
(32 cards)
in what populations do vitamin deficiencies occur in?
alcohol abusers elderly patients patients w/ small bowel resections food faddists malnourished people
what are some general properties of water soluble vitamins
cannot store in body b/c water soluble (lasts a few weeks)
all found in plants (except b12)
precursors of coenzymes involved in intermediary metabolism
vitamin B1
thiamine
coenzyme for enzymes involved in:
carbohydrate metabolism (Krebs cycle)
-pyruvate dehydrgenase
-a-ketoglutarate dehydrogenase
deficiency leads to korsakoffs syndrome
vitamin b1 deficiency
wernikes encephalopathy
confusion, weakness, ataxia, nystagmous
treated w/ glucose and thiamin
w/ administration of glucose, leads to korsakoffs syndrome
brain takes up glucose but cannot progress through krebs cycle, leading to buildup of lactic acid in brain- neuronal death (mammillary bodies)
beriberi
thiamine deficiency
peripheral neuropathy and dilated cardiomyopathy (balloon heart)
flushed, red, sweating- high output heart failure
malnourished from developing world (diet w/ polished rice)
treatment w/ thiamine
vitamin b2
riboflavin
precurors of FMN and FAD
generated by ATP:
b2 gets P from ATP for FMN
b2 gets nucleotide from ATP for FAD
vitamin b2 deficiency
causes fissuring at the angles of the mouth, dermatitis, and purple tongue
vitamin b3
niacin
nicotinic acid or nicotinamide
precursor for NAD or NADP
cofactor for enzymes that catalyze redox rxns
can be synthesized from tryptophan
vitamin b3 deficiency
causes pellagra (sour skin)- dermatitis, diarrhea, dementia, and death (sun sensitive skin rash)
Hartnup disease- tryptophan deficiency
carcinoid syndrome- altered tryptophan metabolism
used to lower LDL and VLDL in type IIb hyperlipoproteinemia (inhibits lipolysis)
vitamin b5
pantothenic acid
component of coenzyme A
vitamin b6
term for pyridoxine, pyridoxal, pyridoxamine
precurors for pyridoxial phosphate
binds to antituberculous drug isoniazid, which causes functional deficiency
isoniazid is administered with vitamin b6
lack of b6 leads to seizures
vitamin b7
biotin
coenzyme for carboxylation rxns- covalently binds to lysine residues on enzymes
vitamine b7 deficiency
bound by protein avidin- protein found in eggs
can get deficient by eating 20 eggs/day
symptoms- dermatitis, glossitis, nausea, depression
vitamin b9
folate
necessary in 1-c metabolism (purine and thymidine synthesis, cell division)
given therapeutically before pregnancy to prevent neural tube defects
supplemented in “enriched foods
vitamin b9 deficiency
megoblastic anemia- immature cells in the blood (rather than bone marrow)
occurs b/c of folate deficiency and rapidly dividing cells like RBCs cannot synthsize new DNA effectively
treated with THF directly (leukovorin)
vitamin b12
cobalamin
precursor for methylcobalamin, needed to synthesize methionine from homocysteine
precursor for deoxyadenosylcobalamin- need for Fatty acid metabolism in brain
not produced by plants
vitamin b12 deficiency
seen in vegans and pts w/ pernicious anemia (lacking intrinsic factor)
causes megoloblastic anemia (used to regenerate THF), dementia, spinal cord degeneration
takes years to present
folate supplements will alleviate anemia, but not the neurologic symptoms (sunacute combined degeneration)
vitamin c
ascorbic acid
needed for post translation hydroxylation of proline, especially in collagen (allows for crosslinks between collagen fibers)
anti-oxidant
causes scurvy- bleeding gums, hemorrhages around hair follicles, poor wound healing, bone pain
mega-doses cause kidney stones
intrinsic factor
binds b12 and helps it get absorbed
how well are fat soluble vitamins stored?
stored well- takes months of inadequate intake to develop deficiency
vitamin A
retinol, retinal, retinoic acid
required for reproduction
retinal- protein essential for vision
retinoic acid- differentiates epithelial cells
obtained from animals or B-carotene in plants
used to treat acne
vitamin A deficiency
causes permanent blindness- first symptom is night blindness, dry eyes, bitots spots, corneal ulceration, some of which can be alleviated w/ Vitamin A administration
signs- corneal epithelial cell dedifferentiation/keratinization- xeropthalmia and bitots spots (Keratin buildup on eyes)
which vitamin should not be given to pregnant women? why?
vitamin A- tetrogenic
vitamin d
produced endogenously from skin by UV radiation, or obtained from animals (d3)/plants (d2)
converted to calcitrol by 2 successive hydroxylation rxns (liver first, then kidney/bone/placenta)
increases calcium uptake by intestine
