niacin by : maryam valavi. introduction o niacin is one of the b complex vitamins. o it is also...
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Niacin
By : Maryam Valavi
Introduction
o Niacin is one of the B Complex Vitamins.o It is also known as Vitamin B3.
o Made from tryptophan; essential nutrient if protein intake is inadequate.
o 60 mg tryptophan converts to 1 mg niacin. nicotinic acid nicotinamid Vitamin PP
Structure
NAD+
NADH
NADP+
NADPH
Function
o Coenzymes are active participants in oxidation-reduction reactions.
o Function in at least 200 reaction in cellular metabolic pathways , Especially ATP producing reactions.
o NAD+ Participates in catabolic reactions . Electron and hydrogen ion acceptor.o NADP+ Important in biochemical pathway for fatty-acid synthesis. Cells that synthesize a lot of fatty acids have higher
concentrations of NADP+. Liver and mammary glands.
Biosynthesis
o The liver can synthesize Niacin from the essential amino acid Tryptophan, but the synthesis is extremely slow and requires vitamin .
o Bacteria in the gut may also perform the conversion but are inefficient.
Sources
Absorption
oBoth forms are readily absorbed from the stomach and intestine by active transport and passive diffusion.
oAlmost all niacin consumed is absorbed.oAt low concentration by active
transportation.oAt high concentration by passive
diffusion.
Transportation
o Both Nicotinic acid AND Nicotinamide bind to plasma proteins for transportation.
Deficiency
Pellagra
o Early stages:AnorexiaIndigestionMuscle weaknessReddened skinRough skin
o Advanced stages:3 D’s of pellagra: dermatitis, diarrhea,
dementia
Dermatitis of Pellagra
Recommended Levels
o Pediatrics1 to 3 years (6 mg)4 to 8 years (8 mg)9 to 13 years (12 mg)
o YouthMales 14 to 18 years (16 mg)Females 14 to 18 years (14 mg)
o AdultsMales 19 and older (16 mg)Female 19 and older (14 mg)Pregnant females (18 mg)Breastfeeding females (17mg)
Medicinal Uses
o Niacin in very large doses is used to decrease blood cholesterol levels and reduce the risk of heart attack.
o Treatment of Pellagra.
Toxicityo (> 35 mg/day)
o Used to treat high cholesterol but often results in several unpeasanlt side effects including:
Flushing
Heartburn, nausea, vomiting
Liver injury, jaundice, hepatitis, liver failure
Hyperuricemia and gout
Glucose intolerance
Niacin AND Cancer
o Clearly, a deficiency of any vitamin that is involved in building new copies of your DNA is crucial in the formation of cancer.
o A further indication of the involvement of B3 came with 2010 research into beneficial bacteria and the production of sodium butyrate in the gut from certain foods. The researchers concluded that this chemical could actually kill cancer cells and recommended that people should increase their B3 levels to obtain the same effect.
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