Niacin Flashcards
Vitamin ____
refers to
B3
nicotinic acid and nicotinamide
Found in B, M, M, E, W, F
lower bioavailability in
high in
Flour enriched w
Median intake usually
beans, milk, meat, eggs, grains, flour
cereal
beans, milk, meat eggs
free niacin, highly available
exceeds recommended allowance
Nicotinic acid and nicotinamide are
important in
also
absorbed in
passively taken up by
intracellular nicotinic acid/nicotinamide converted to
small amount is generated in liver by conversion of
precursors to coenzymes (NAD and NADP)
oxidation/reduction rxns
DNA repair, calcium mobilization
stomach, SI
liver, kidneys, RBC
NADP/NAD in tissues w high met activity (liver/muscle)
tryptophan
Deficiency causes
pellagra sx
Mostly in people w
In US
also in
or
pellagra- chronic wasting dz
erythematous, symmetrical dermatitis, dementia, diarrhea
corn based diet (China/Africa/India)
alcoholics
congenital defects of intestine/kidney absorption of tryptophan (Hartnup dz)
carcinoid syndrome (inc conversion of tryptophan to serotonin)
In famine/displacement, pellagra results from
such as
lack of niacin and def of micronutrients required for conversion of thiamine to Niacin
Iron, riboflavin, pyridoxine
Early sx of pellagra
Characteristic dermatitis
location
later
think of 4 d’s
loss of appetite, gen weakness, ab pain, vomiting, glossitis
pigmented, scaling rash in areas exposed to sun
C3-C4 dermatome circumferentially (Casal’s necklace)
diarrhea, depression, seizure, dementia
dermatitis, diarrhea, dementia and death
Pellagra treated w
higher does used w
oral supplemented nicotinamide and nicotinic acid
dyslipidemia
Toxicity presents w
usually when
flushing starts in
other sx
most serious complication
PG mediated flushing- niacin binds to GPCR
Nicotinic acid taken as supplement or therapy (dyslipidemia)
face
skin dryness, itching, paresthesia, HA
hepatic toxicity
