Nicotinic Acid
<p ><b>Niacin</b> (also known as <b>vitamin B<sub >3</sub></b>, <b>nicotinic acid</b> and <b>vitamin PP</b>) is an <a href="http://en.wikipedia.org/wiki/Organic_compound" title="Organic compound" >organic compound</a> with the <a href="http://en.wikipedia.org/wiki/Chemical_formula" title="Chemical formula" >formula</a> C<sub >6</sub>H<sub >5</sub>NO<sub >2</sub> and, depending on the definition used, one of the forty to eighty <a href="http://en.wikipedia.org/wiki/Essential_nutrient" title="Essential nutrient" >essential human nutrients</a>.</p>
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Niacin is one of five vitamins (when lacking in human diet) associated with a <a href="http://en.wikipedia.org/wiki/Pandemic" title="Pandemic" >pandemic</a>
<a href="http://en.wikipedia.org/wiki/Nutrition_disorder" title="Nutrition disorder" >deficiency disease</a>:
niacin deficiency (<a href="http://en.wikipedia.org/wiki/Pellagra" title="Pellagra" >pellagra</a>),
<a href="http://en.wikipedia.org/wiki/Vitamin_C" title="Vitamin C" >vitamin C</a> deficiency (<a href="http://en.wikipedia.org/wiki/Scurvy" title="Scurvy" >scurvy</a>),
<a href="http://en.wikipedia.org/wiki/Thiamin" title="Thiamin" class="mw-redirect" >thiamin</a> deficiency (<a href="http://en.wikipedia.org/wiki/Beriberi" title="Beriberi" >beriberi</a>),
<a href="http://en.wikipedia.org/wiki/Vitamin_D" title="Vitamin D" >vitamin D</a> deficiency (<a href="http://en.wikipedia.org/wiki/Rickets" title="Rickets" >rickets</a>),
<a href="http://en.wikipedia.org/wiki/Vitamin_A_deficiency" title="Vitamin A deficiency" >vitamin A deficiency</a> (<a href="http://en.wikipedia.org/wiki/Night_blindness" title="Night blindness" class="mw-redirect" >night blindness</a> and other symptoms). </p>
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Niacin has been used for over 50 years to increase levels of <a href="http://en.wikipedia.org/wiki/High-density_lipoprotein" title="High-density lipoprotein" >HDL</a> in the blood and has been found to modestly decrease the risk of cardiovascular events in a number of controlled human trials.</p>
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This colorless, water-soluble solid is a derivative of <a href="http://en.wikipedia.org/wiki/Pyridine" title="Pyridine" >pyridine</a>, with a <a href="http://en.wikipedia.org/wiki/Carboxyl_group" title="Carboxyl group" class="mw-redirect" >carboxyl group</a> (COOH) at the 3-position. </p>
<p>
Other forms of vitamin B<sub >3</sub> include the corresponding <a href="http://en.wikipedia.org/wiki/Amide" title="Amide" >amide</a>, <a href="http://en.wikipedia.org/wiki/Nicotinamide" title="Nicotinamide" >nicotinamide</a> ("niacinamide"), where the carboxyl group has been replaced by a carboxamide group (CONH<sub >2</sub>), as well as more complex amides and a variety of esters. </p>
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Niacin and Vitamin B3 are the generic terms for both nicotinic acid and nicotinamide, which are often used interchangeably to refer to any member of this family of compounds, since they have similar biochemical activity.<sup id="cite_ref-efsa.europa.eu_2-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Nicotinic_acid#cite_note-efsa.europa.eu-2" >[3]</a></sup></p>
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Niacin cannot be directly converted to nicotinamide, but both compounds could be converted to <a href="http://en.wikipedia.org/wiki/Nicotinamide_adenine_dinucleotide" title="Nicotinamide adenine dinucleotide" >NAD</a> and <a href="http://en.wikipedia.org/wiki/NADP" title="NADP" class="mw-redirect" >NADP</a> <i><a href="http://en.wikipedia.org/wiki/In_vivo" title="In vivo" >in vivo</a></i>. </p>
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Although the two are identical in their vitamin activity, nicotinamide does not have the same pharmacological effects (lipid modifying effects) as niacin. </p>
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Nicotinamide does not reduce cholesterol or cause <a href="http://en.wikipedia.org/wiki/Flushing_(physiology)" title="Flushing (physiology)" >flushing</a>.<sup id="cite_ref-3" class="reference" ><a href="http://en.wikipedia.org/wiki/Nicotinic_acid#cite_note-3" >[4]</a></sup> </p>
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Nicotinamide may be toxic to the liver at doses exceeding 3 g/day for adults.<sup id="cite_ref-4" class="reference" ><a href="http://en.wikipedia.org/wiki/Nicotinic_acid#cite_note-4" >[5]</a></sup> </p>
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Niacin is a precursor to<a href="http://en.wikipedia.org/wiki/Nicotinamide_adenine_dinucleotide" title="Nicotinamide adenine dinucleotide" >NAD+/NADH</a> and <a href="http://en.wikipedia.org/wiki/NADPH" title="NADPH" class="mw-redirect" >NADP+/NADPH</a>, which play essential <a href="http://en.wikipedia.org/wiki/Metabolism" title="Metabolism" >metabolic</a> roles in <a href="http://en.wikipedia.org/wiki/Living_cell" title="Living cell" class="mw-redirect" >living cells</a>.<sup id="cite_ref-isbn1-57259-153-6_5-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Nicotinic_acid#cite_note-isbn1-57259-153-6-5" >[6]</a></sup> </p>
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Niacin is involved in both DNA repair, and the production of <a href="http://en.wikipedia.org/wiki/Steroid_hormone" title="Steroid hormone" >steroid hormones</a> in the <a href="http://en.wikipedia.org/wiki/Adrenal_gland" title="Adrenal gland" >adrenal gland</a>.</p>