Definition
Present in fruits and other plant materials. Nutrient supplement. Vitamin, enzyme cofactor [DFC] Niacin (also known as vitamin B3, nicotinic acid and vitamin PP) is an organic compound with the formula C6H5NO2 and, depending on the definition used, one of the forty to eighty essential human nutrients. This colorless, water-soluble solid is a derivative of pyridine, with a carboxyl group (COOH) at the 3-position. Other forms of vitamin B3 include the corresponding amide, nicotinamide ('niacinamide'), where the carboxyl group has been replaced by a carboxamide group (CONH2), as well as more complex amides and a variety of esters. The terms niacin, nicotinamide, and vitamin B3 are often used interchangeably to refer to any member of this family of compounds, since they have the same biochemical activity. [Wikipedia]
Description
Nicotinic acid, also known as niacin or vitamin B3, is a water-soluble vitamin whose derivatives such as NADH, NAD, NAD+, and NADP play essential roles in energy metabolism in the living cell and DNA repair. The designation vitamin B3 also includes the amide form, nicotinamide or niacinamide. Severe lack of niacin causes the deficiency disease pellagra, whereas a mild deficiency slows down the metabolism decreasing cold tolerance. The recommended daily allowance of niacin is 2-12 mg a day for children, 14 mg a day for women, 16 mg a day for men, and 18 mg a day for pregnant or breast-feeding women. It is found in various animal and plant tissues and has pellagra-curative, vasodilating, and antilipemic properties. The liver can synthesize niacin from the essential amino acid tryptophan (see below), but the synthesis is extremely slow and requires vitamin B6; 60 mg of tryptophan are required to make one milligram of niacin. Bacteria in the gut may also perform the conversion but are inefficient.
Nicotinic Acid is Found in These Foods
Nicotinic Acid Health Effects
- Allergenic
- Anti acrodynic
- Anti allergic
- Anti Alzheimeran
- Anti amblyopic
- Anti anginal
- Anti cataract
- Anti convulsant
- Anti dementia
- Anti dermatitic
- Anti diabetic
- Anti dysphagic
- Anti epileptic
- Anti hangover
- Anti histaminic
- Anti hyperactivity
- Anti insomnic
- Anti Lyme
- Anti Meniere's
- Anti pellagric
- Anti neuralgic
- Anti Parkinsonian
- Anti Raynaud's
- Anti scotomic
- Anti spasmodic
- Anti vertigo
- Cancer preventive
- Cardioprotective
- Circulotonic
- Fibrinolytic
- Hepatoprotective
- Hepatotoxic
- Hypolipidemic
- Sedative
- Serotoninergic
- Vasodilator
General Information
- Metabolism: Niacin is rapidly metabolized and undergoes extensive first-pass metabolism in the liver. The drug is converted to several metabolites, including nicotinuric acid (NUA), nicotinamide, and nicotinamide adenine dinucleotide (NAD). At doses used to treat hyperlipoproteinemia, the principal metabolic pathways appear to be saturable, and niacin is thought to exhibit nonlinear, dose-dependent pharmacokinetics. (L1323) Half Life: 20-45 minutes.
- Uses/Sources: For the treatment of type IV and V hyperlipidemia. It is indicated as ajunctive therapy. It can be found in various foods, such as liver, chicken, beef, fish, cereal, peanuts and legumes. Niacin is also used as a pharmaceutical to reverse atherosclerosis. (A729)
- Health Effects: Niacin at extremely high doses can have life-threatening acute toxic reactions. Extremely high doses of niacin can also cause niacin maculopathy, a thickening of the macula and retina which leads to blurred vision and blindness. This maculopathy is reversible after stopping niacin intake. Side effects of hyperglycemia, cardiac arrhythmias and birth defects have also been reported. (A729)
- Symptoms: Nicotinic acid can cause vasodilation of cutaneous blood vessels resulting in increased blood flow, principally in the face, neck and chest. This produces the niacin- or nicotinic acid-flush. The niacin-flush is thought to be mediated via the prostaglandin prostacyclin. Histamine may also play a role in the niacin-flush. Flushing is the adverse reaction first observed after intake of a large dose of nicotinic acid, and the most bothersome one.
- Treatment: Supportive measures should be undertaken in the event of an overdose. (L1712)
- Route of Exposure: Oral (L1436) ; Intramuscular (L1436). Both nicotinic acid and nicotinamide are efficiently absorbed from the stomach and small intestine.
Toxicity
- Carcinogenicity: No indication of carcinogenicity to humans (not listed by IARC).
- Toxicity: LD50: 7000 mg/kg (Oral, Rat) (T14) LD50: 730 mg/kg (Intraperitoneal, Rat) (T14) LD50: 3500 mg/kg (Subcutaneous, Mouse) (T14)
Mechanism of Action
| Target Name | Mechanism of Action | References |
|---|---|---|
| Nicotinamide N-methyltransferase | Niacin binds to nicotinate D-ribonucleotide phyrophsopate phosphoribosyltransferase, nicotinic acid phosphoribosyltransferase, nicotinate N-methyltransferase and the niacin receptor. Niacin is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are vital cofactors for dozens of enzymes. The mechanism by which niacin exerts its lipid lowering effects is not entirely understood, but may involve several actions, including a decrease in esterification of hepatic triglycerides. Niacin treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions. (A358, A359) |
17016423 17139284 |
| Hydroxycarboxylic acid receptor 2 | Niacin binds to nicotinate D-ribonucleotide phyrophsopate phosphoribosyltransferase, nicotinic acid phosphoribosyltransferase, nicotinate N-methyltransferase and the niacin receptor. Niacin is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are vital cofactors for dozens of enzymes. The mechanism by which niacin exerts its lipid lowering effects is not entirely understood, but may involve several actions, including a decrease in esterification of hepatic triglycerides. Niacin treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions. (A1386, A1387, A1388, A1380, A1381) |
20184326 20380810 20444602 16099840 20615702 15580557 20452209 18752940 16018973 12522134 18760600 17452318 20460384 17994679 16389067 18665582 21167710 18029181 19307116 19309152 12646212 19592242 |
| Nicotinate-nucleotide pyrophosphorylase [carboxylating] | Niacin binds to nicotinate D-ribonucleotide phyrophsopate phosphoribosyltransferase, nicotinic acid phosphoribosyltransferase, nicotinate N-methyltransferase and the niacin receptor. Niacin is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are vital cofactors for dozens of enzymes. The mechanism by which niacin exerts its lipid lowering effects is not entirely understood, but may involve several actions, including a decrease in esterification of hepatic triglycerides. Niacin treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions. (A1383, A1384, A1385) |
11758903 15837705 15753098 |
| Hydroxycarboxylic acid receptor 3 | Niacin binds to nicotinate D-ribonucleotide phyrophsopate phosphoribosyltransferase, nicotinic acid phosphoribosyltransferase, nicotinate N-methyltransferase and the niacin receptor. Niacin is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are vital cofactors for dozens of enzymes. The mechanism by which niacin exerts its lipid lowering effects is not entirely understood, but may involve several actions, including a decrease in esterification of hepatic triglycerides. Niacin treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions. (A1378, A1379, A1380, A1381, A1382) |
16018973 16322797 12563315 15929991 16099840 16389067 |