Niacin, also known as nicotinic acid 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, which in turn decreases cold tolerance and is a potential contributing factor towards obesity. Discovery
Nicotinic acid was first discovered from the oxidation of nicotine. When the properties of nicotinic acid were discovered, it was thought prudent to choose a name to dissociate it from nicotine and to avoid the idea that either smoking provided vitamins or that wholesome food contained a poison. The resulting name 'niacin' was derived from nicotinic acid + vitamin.
Industrial use
Nicotinic acid reacts with hemoglobin and myoglobin in meat to form a brightly coloured complex, and thus has been used as a food additive, typically to improve the colour of minced (ground) meat. However, sometimes excess niacin is added to the meat during processing. Though still licensed as a food colouring agent in some countries, it is not licensed as such in Europe.
Bioavailability
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. For this reason, eating lots of tryptophan is not an adequate substitute for consuming niacin. However, this explains why pellagra requires a deficiency of protein as well as niacin.
Medical use
Niacin in large quantities is a vasodilator. Large amounts of niacin (either from vitamin B3 tablets or from treated meats) may cause dose related, harmless and short-lived sensations ranging from a mildly pleasant warm flush to tingling to extreme skin flushing resembling a sunburn, itching, gastric disturbances, and lowering of blood pressure. This occurs as a result of releasing histamine about 1 hour after ingesting the niacin. The flushing is no longer present after the first day if gram amounts are consumed in divided doses as recommended for high cholesterol. The amide form (strictly speaking a provitamin) does not cause these side effects, but is also not as easily assimilated by the body.
Large doses of niacin (as nicotinic acid, but not the niacinamide form) are prescribed to combat high blood pressure and to broadly improve blood cholesterol levels. Niacin is used to treat dyslipidemas because of its low cost and its unique ability to improve lipid profiles for ApoB, LDL, small dense LDL, HDL, HDL2b - an extremely good cholesterol, Lp(a), fibrinogen and trigycerides [1][2]. Pharmacologic doses of niacin (1.5 to 6 grams/day in divided doses) typically reduce LDL cholesterol levels by 10 to 25 percent and triglyceride levels by 20 to 50 percent. HDL cholesterol levels are also typically increased by 15 to 35 percent.1 Brand-name medications include NiaspanŽ, NiacorŽ and NicolorŽ. Most slow-release pharmaceutical preparations are dangerous to the liver. There is disagreement as to if nicotinic acid is harmful to the liver, possibly due to the confusion with the more dangerous pharmaceutical preparations.
The niacin treatment discoverer, Abram Hoffer, and other orthomolecular proponents generally add a full spectrum vitamin B formulation, such as B-50, and 1 to 4 times as much vitamin C as niacin to reduce liver stress. Liver cell activation and stress is easily monitored in the liver enzyme panel along with blood cholesterol measurements. Because of the liver stress associated with heavy alcohol consumption, regular drinkers and alcoholics may experience antabuse-like reactions with pharmacologic levels of niacin.
An esterified, no-flush derivative of niacin called Inositol hexanicotinate (IHN), also known as inositol hexaniacinate, is slowly hydrolyzed and has no reported side effects using 4 grams daily3. Peak blood concentrations have been reported to be at 10 hours, but suggested dosing is at least 4 times a day. It is used extensively in Europe for Raynaud's disease. There is no known monotherapic treatment for cholesterol dyslipidemas that is more broadly effective and as gentle[3].
Another form of vitamin B3, niacinamide, has been used since the 1940's for osteoarthritis and rheumatoid arthritis with tremendous success[4][5][6] reported by William Kaufman, MD, PhD[7] (1910-2000). Kaufman's recommended usage is about 4 grams a day in divided doses, more frequently being better. Dr. Kaufman advocated 500mg, and even 250mg doses, many times a day as being better than 1,000 mg 4 times a day. Nicotinic acid at least partially breaks down to niacinamide, so less niacinamide is needed if niacin treament for cholesterol is being used. Niacinamide may be safer for the liver than nicotinic acid, but nutritional supplement proponent and expert Michael Murray recommends testing liver function every 3 months when taking any high-dose form of niacin. Dr. Hoffer reports he has never seen liver problems result from taking any natural form of niacin with at least equal amounts of vitamin C [8].
Vitamin B3 has also been used in nutritional treatments of alcoholism, cancer, schizophrenia, senility and other mental illnesses by orthomolecular practitioners[9]. These treatments are largely based on improved circulation, NAD related energetics and cellular repairs, and the correction of abnormal indole metabolites. Often the nicotinamide form is used, as its lack of a flush is easier to self administer with new patients. Unfortunately orthomolecular psychiatric treatments remain adversarially disputed over disagreements about measurement, diagnosis, efficacy, protocols and specific populations.
