Niacin (Nicotinic Acid)
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Introduction
Niacin is an essential component of NAD and NADP.
Niacin, when taken in large doses, blocks the breakdown of fats in adipose tissue, thus altering blood lipid levels. Niacin is used in the treatment of hyperlipidemia because it reduces very-low-density lipoprotein (VLDL), a precursor of low-density lipoprotein (LDL) or "bad" cholesterol. Because niacin blocks breakdown of fats, it causes a decrease in free fatty acids in the blood and, as a consequence, decreased secretion of VLDL and cholesterol by the liver.
Daily Requirements
Sources
Biological Roles
NAD serves as a coenzyme for a variety of dehydrogenation reactions involved in the meatabolism of fat, carbohydrates, and amino acids.
NADP is involved in other dehydrogenation reactions, particularly those in the hexose-monophosphate shunt of glucose metabolism.
In pharmacologic doses, niacin is used in treating hypercholesterolemia. It acts to lower plasma LDL levels by reducing hepatic synthesis of VLDL and ApoB.
Deficiency
Pellagra- dermatitis, diarrhrea, dementia.
Overdose
Can cause flushing, itching, headache
hepatotoxicity, GI problems
peptic ulcer activiation
hyperglycemia and reduced insulin activity
Resources and References
Knopp RH. N Engl J Med 1999;341:498-511
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