Vitamin B3 (niacin)
Niacin, also called
nicotinic acid, pyridine 3-carboxylic acid,
vitamin B3 or vitamin PP, is a water soluble vitamin. Niacin is derived from two compounds: nicotinic acid and niacinamide. It improves circulation and reduces the cholesterol level in the blood; maintains the nervous system; helps metabolize protein, sugar and fat; reduces high blood pressure; increases energy through proper utilization of food; prevents pellagra; helps maintain a healthy skin, tongue and digestive system. The known biological roles of niacin are attributable to the function of its active metabolites, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). Niacin forms part of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are important intercellular carriers of reducing electrons in the electron transport system in living organisms. Niacin is a precursor to the biosynthesis of NAD and nicotinamide NADP. Nicotinamide nucleotides (NAD and NADP) participate in a wide array of oxidation-reduction reactions catalyzed by dehydrogenase or oxido-reductase enzymes. Virtually every aspect of cellular metabolism involves NAD/NADH or NADP/NADPH dependent reactions. In absence of sufficient supplies of nicotinamide nucleotides or niacin precursors for nicotinamide nucleotide biosynthesis, cellular functions and life itself would be impairedNiacin containing coenzymes participate in a variety of biological reactions, e.g., lipid catabolism and oxidative deamination. In fact, niacin deficiency has been identified as the leading cause of a medical malady known as pellagra. Niacin is an important dietary supplement. For example, niacin plays an important role in metabolism, acting as an hydrogen and electron transfer agent in carbohydrate metabolism. Vitamin B3 is required for cell respiration, helps in the release of energy and metabolism of carbohydrates, fats, and proteins, proper circulation and healthy skin, functioning of the nervous system, and normal secretion of bile and stomach fluids. It is used in the synthesis of sex hormones, treating schizophrenia and other mental illnesses, and as a memory-enhancer. Niacin inhibits lipoprotein synthesis by preventing the secretion of very low density lipoprotein (VLDL) from the liver. Because VLDL is a precursor for the intermediate density lipoproteins (IDL) and LDL, the circulating levels of all of the atherogenic lipoprotein fractions are decreased. In addition, niacin decreases levels of lipoprotein a, which has been associated with a two-fold increase in the relative risk of coronary artery disease. Niacin is used orally for the treatment of hyperlipidemia and has been shown to be effective in reducing total plasma cholesterol (C), low density lipoproteins LDL-C and very low density lipoprotein triglycerides (VLDL-triglycerides), all of which are associated with health risks, while raising serum levels of high density lipoproteins (HDL-C) which are considered a "healthy" lipoprotein. It is highly effective in reducing elevated levels of plasma cholesterol and triglycerides, and is thus useful in treating hypercholesterolemia. In addition, niacin exhibits adipose tissue lipolysis, reduces plasma free fatty acid levels and decreases very low density lipoprotein synthesis. In addition, niacin has demonstrated value in preventing manifestations of arteriosclerotic heart disease. In humans, niacin equivalents can be obtained from dietary nicotinate,
nicotinamide, and tryptophan. Consequently, niacin status depends on the amount of these in the diet and on factors that influence uptake, distribution, efficiency of conversion to tissue NAD and NADP, and excretion or reutilization of the nicotinamide moiety formed by the turnover of NAD and NADP. Niacin deficiency symptoms include pellagra, gastrointestinal disturbance, nervousness, headaches, fatigue, mental depression, vague aches and pains, irritability, loss of appetite, insomnia, skin disorders, muscular weakness, indigestion, and canker sores.
Vitamin B3 (niacin) categories
Niacinamide (nicotinamide)
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