A white crystalline acid, C5H4NCOOH, that is a component of the vitamin B complex found in meat, wheat germ, dairy products, and yeast and is used to treat and prevent pellagra. Also called nicotinic acid.
[NI(COTINIC) AC(ID) + -IN.]
niacin
Dictionary:
ni·a·cin (nī'ə-sĭn)  |
n.
A white crystalline acid, C5H4NCOOH, that is a component of the vitamin B complex found in meat, wheat germ, dairy products, and yeast and is used to treat and prevent pellagra. Also called nicotinic acid.
A white crystalline acid, C5H4NCOOH, that is a component of the vitamin B complex found in meat, wheat germ, dairy products, and yeast and is used to treat and prevent pellagra. Also called nicotinic acid.
| Britannica Concise Encyclopedia: niacin |
For more information on niacin, visit Britannica.com.
| Sci-Tech Encyclopedia: Niacin |
A vitamin also known as nicotinic acid, a component of the vitamin B complex. It is a white water-soluble powder stable to heat, acid, and alkali, with the structure shown below.
Many animals, including humans, are capable of synthesizing niacin in varying degrees from the amino acid tryptophan. Niacin is widely distributed in foods. Yeasts, wheat germ, and meats, particularly organ meats, are rich sources of the vitamin. Some foods such as milk are relatively poor sources of niacin but contain generous quantities of tryptophan.
Niacin-deficiency disease is known as pellagra and is particularly prevalent among the poor people whose diet is largely corn. The recommended dietary allowance for niacin is 6.6 niacin equivalents per 1000 kcal. See also Vitamin.
| Food and Nutrition: niacin |
A vitamin; one of the B complex without a numerical designation. It is sometimes (incorrectly) referred to as vitamin B3, and formerly vitamin PP (pellagra preventative). Deficiency leads to pellagra, which is fatal if untreated. Niacin is the generic descriptor for two compounds that have the biological activity of the vitamin: nicotinic acid and its amide, nicotinamide. In USA niacin is used specifically to mean nicotinic acid, and niacinamide for nicotinamide.
The metabolic function of niacin is in the coenzymes NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate), which act as intermediate hydrogen carriers in a wide variety of oxidation and reduction reactions.
Niacin can also be formed in the body from the amino acid tryptophan; on average 60 mg of dietary tryptophan is equivalent to 1 mg of preformed niacin. The total niacin content of foods is generally expressed as mg niacin equivalents; the sum of preformed niacin plus one-sixtieth of the tryptophan. This means that most foods that are good sources of protein are also good sources of niacin. In cereals niacin is largely present as niacytin, which is not biologically available; therefore the preformed niacin content of cereals is generally ignored when calculating intakes. Free niacin is added to white flour and enriched breakfast cereals in many countries.
| Food and Fitness: niacin |
nicotinamide; nicotinic acid; vitamin B3
A water-soluble nutrient belonging to the vitamin B complex. Like other B vitamins, niacin plays an important role in carbohydrate metabolism. It is also indispensable for fat and protein metabolism, and inhibits cholesterol synthesis.
The link between niacin (specifically nicotinic acid) and cholesterol reduction was first made by Dr R. Altschul in 1955, but it was brought to public attention in 1990 by Robert Kowalski in his book entitled The 8-week cholesterol cure. As a result, some people have taken excessive amounts of niacin in the belief that it will protect against high blood cholesterol levels. This practice is potentially dangerous. High doses (greater than 500 mg per day), or slow-release preparations of niacin which elevate blood concentrations for a long time, can lead to irreversible liver damage. Large doses of niacin can also decrease fat mobilization and the ability to do physical work.
Although the precise amount varies depending on energy expenditure, approximately 20 milligrams of niacin are needed per day. The body stores very little. It can synthesize niacin from the amino acid tryptophan. This synthesis may be enough to meet the daily requirement, but niacin can also be obtained from foods such as meat, fish, brown rice, beans, and yeast extract (the richest source, with as much as 67 mg per 100 g). Deficiency can result in a disease called pellagra, early symptoms of which include muscular weakness, general fatigue, loss of appetite, indigestion, and minor skin complaints. Pellagra is unlikely to occur in individuals who eat a balanced diet.
| Dental Dictionary: niacin |
n
vitamin B3
trade name: generic niacin (nicotinic acid); drug class: vitamin B3; action: needed for conversion of fats, protein, carbohydrates by oxidation-reduction; acts directly on vascular smooth muscle, causing vasodilation; uses: pellagra, hyperlipidemias, peripheral vascular disease.
| Alternative Medicine Encyclopedia: Niacin |
Description
Niacin, also known as Vitamin B3, is important for the normal function of many bodily processes. Like other B vitamins, it is water-soluble and plays a role in turning food into energy, as well as in the metabolism of fats and carbohydrates. Niacin can also act as an antioxidant within cells, which means it can destroy cell-dam-aging free radicals. In conjunction with riboflavin and pyridoxine, it helps to keep the skin, intestinal tract and nervous system functioning smoothly.
General Use
The recommended daily allowance (RDA) of niacin for infants under six months is 5 mg. Babies from six months to one year of age require 6 mg. Children need 9 mg at one to three years of age, 12 mg at four to six years, and 13 mg at seven to 10 years. Women need 15 mg from 11-50 years, and 13 mg thereafter. Somewhat more is required for pregnancy (17 mg) and lactation (20 mg). Men require 17 mg from 11-14 years of age, 20 mg from 15-18 years, 19 mg from 19-50 years, and 15 mg at 51 years and older.
Niacin in the form of nicotinic acid can be taken in very large doses to decrease blood cholesterol levels and reduce the risk of heart attack. Niacin is an important part of the treatment of familial hyperlipidemia, an inherited disorder characterized by high blood cholesterol levels and increased risk of heart disorders. The amount of niacin required is between 2 and 3 g per day. Although treatment with niacin is considered the best strategy for normalizing blood cholesterol levels as of 2002, it should not be undertaken without professional medical advice and supervision. Niacin has been singled out as a dietary supplement for which people frequently exceed the upper limits of safe intake. One Canadian study found that 47% of adults who were taking dietary supplements were taking niacin above recommended levels.
Certain conditions preclude the use of high doses of niacin. These disorders include gout, diabetes, peptic ulcer, liver or kidney disease, and high blood pressure requiring medication. Even in the absence of these conditions, a patient on high doses of niacin should be closely monitored to be sure the therapy is both effective and without complications. A frequent side effect of this therapy is extreme flushing of the face and neck. It is harmless, but can be unpleasant. An alternative form of nicotinic acid that does not cause flushing is inositol hexaniacinate. "Slow release" niacin also causes less flushing, but should not be taken as there is higher risk of liver inflammation.
There is some evidence that niacinamide used on a long-term basis can prevent the onset of juvenile diabetes in many susceptible children. Those who have been newly diagnosed with juvenile diabetes may also benefit by extending the time that the pancreas continues to produce a small amount of insulin. The advice of a health care provider should be sought for these uses.
Inositol hexaniacinate can be helpful for people suffering from intermittent claudication. This condition causes leg pain with exercise due to poor blood flow to the legs. Dilation of the blood vessels caused by the inositol hexaniacinate relieves this condition to some extent, allowing the patient to walk farther with less pain.
Other conditions that may be benefited by supplemental niacinamide include vertigo, tinnitus, premenstrual syndrome (PMS) headaches, and osteoarthritis. Raynaud's phenomenon reportedly may be improved by large doses of inositol hexaniacinate. A health care provider should be consulted for these uses. Niacin is not effective for the treatment of schizophrenia.
Preparations
Natural Sources
Tuna is one of the best sources of niacin, but many other foods contain the vitamin. Most processed grain products are fortified with niacin, as well as other B vitamins. Although niacin is not destroyed by cooking, it does leach into water, so cooking with minimal liquid best preserves it. The amino acid tryptophan is widely found in foods high in protein, and about half of the tryptophan consumed is used to make niacin. Cottage cheese, milk, fowl, and tuna are some of the foods that are highest in tryptophan.
Supplemental Sources
Niacin can be purchased as an oral single vitamin product. A balanced B complex supplement is preferred over high doses of an individual vitamin unless there is a specific indication. Supplements should be stored in a cool, dry place, away from light, and out of the reach of children.
Deficiency
A serious deficiency of niacin causes a condition called pellagra. Once quite common in all countries, it has become rare outside of areas in which poor nutrition is still the norm. Affected groups include refugees displaced by war as well as populations affected by such emergency situations as famine. The symptoms of pellagra include dermatitis, dementia, and diarrhea.
Milder deficiencies of niacin can cause similar, but less severe symptoms. Dermatitis, especially around the mouth, and other rashes may occur, along with fatigue, irritability, poor appetite, indigestion, diarrhea, headache, and possibly delirium.
Risk Factors for Deficiency
Severe niacin deficiency is uncommon in most parts of the world, but some people may need more than the RDA in order to maintain good health. Vegans, and others who do not eat animal protein, should consider taking a balanced B vitamin supplement. Others that may need extra niacin and other B vitamins may include people under high stress, including those experiencing chronic illnesses, liver disease, sprue, or poor nutritional status. People over 55 years old are more likely to have a poor dietary intake. Certain metabolic diseases also increase the requirement for niacin. Those who abuse nicotine, alcohol or other drugs are very frequently deficient in B vitamins, but use of niacin with alcohol can cause seriously low blood pressure. A health care professional can determine if supplementation is appropriate.
Precautions
Niacin should not be taken by anyone with a B vitamin allergy, kidney or liver impairment, severe hypotension, un-stable angina, arterial hemorrhage, or coronary artery disease. Supplemental niacin can exacerbate peptic ulcers. Diabetics should use caution as supplements of either niacin or niacinamide can alter medication requirements to control blood glucose. Supplements can raise uric acid levels, and aggravate gout in people with this condition. Pregnant women should not take high doses of niacin, or any supplement, except on the advice of a health care provider.
Health care should be sought immediately if certain symptoms occur following niacin supplementation. These include abdominal pain, diarrhea, nausea, vomiting, yellowing of the skin, faintness, or headache. Such symptoms may indicate excessively low blood pressure or liver problems. Heart palpitations and elevated blood sugar are also potential effects.
Side Effects
High doses of niacin can cause a harmless but un-pleasant flushing sensation as well as darkening of the urine. The "no-flush" form can lessen this complication.
Interactions
Niacin supplements should not be taken by anyone on medication for high blood pressure, due to the potential for hypotension. Isoniazid, a drug used to treat tuberculosis, inhibits the body's ability to make niacin from tryptophan. Extra niacin may be required. Supplements may also be needed by women taking oral contraceptives. Concomitant use of niacin with statin class drugs to lower cholesterol can cause myopathy. Cholestyramine and cholestipol, older medications to lower cholesterol, should be taken at a different time than niacin or they will reduce its absorption. Transdermal nicotine used with niacin is likely to cause flushing and dizziness. Carbamazepine, an antiseizure medication, is more likely to cause toxicity in combination with niacin.
Resources
Books
Bratman, Steven, and David Kroll. Natural Health Bible. Prima Publishing, 1999.
Griffith, H. Winter. Vitamins, Herbs, Minerals & supplements: the complete guide. Arizona: Fisher Books, 1998.
Jellin, Jeff, Forrest Batz, and Kathy Hitchens. Pharmacist's letter/Prescriber's Letter Natural Medicines Comprehensive Database. California: Therapeutic Research Faculty, 1999.
Pressman, Alan H., and Sheila Buff. The Complete Idiot's Guide to Vitamins and Minerals. New York: alpha books, 1997.
Periodicals
Batiste, M. C., and E. J. Schaefer. "Diagnosis and Management of Lipoprotein Abnormalities." Nutrition in Clinical Care: An Official Publication of Tufts University 5 (May-June 2002): 115-123.
Gotto, A. M. Jr. "Management of Dyslipidemia." American Journal of Medicine 112 (June 3, 2002) (Supplement 8A): 10S-18S.
Hopkins, P. M. "Familial Hypercholesterolemia." Curren Treatment OPtions in Cardiovascular Medicine 4 (April 2002): 121-128.
Prinzo, Z. W., Z. W. Prinzo, and D. Benoist. "Meeting the Challenges of Micronutrient Deficiencies in Emergency-Affected Populations." Proceedings of the Nutrition Society 61 (May 2002): 251-257.
Troppmann, L., K. Gray-Donald, and T. Johns. "Supplement Use: Is There Any Nutritional benefit?" Journal of the American Dietetic Association 102 (June 2002): 818-825.
Organizations
American Dietetic Association. 216 West Jackson Blvd., Chicago, IL 60606. (312) 899-0040.
World Health Organization (WHO). Avenue Appia 20, 1211 Geneva 27, Switzerland. (+41 22) 791-2111.
[Article by: Judith Turner; Rebecca J. Frey, PhD]
| Sports Science and Medicine: niacin |
nicotinic acid; vitamin B3
A water-soluble vitamin belonging to the B-complex. It is a component of nicotinamide adenine dinucleotide). NAD and plays an important role in respiratory metabolism. When niacin is present in the blood in high concentrations it has insulin-like effects and inhibits fat mobilization. Enteric bacteria may produce some niacin in the intestine. Meat and yeast products are rich sources of niacin. Deficiency causes pellagra, characterized by diarrhoea, dermatitis, and mental disturbance.
| Veterinary Dictionary: niacin |
A water-soluble vitamin of the B complex found in various animal and plant tissues. Essential for normal carbohydrate metabolism. Most natural animal feeds have high enough content to avoid need for supplementation, except for pigs fed a heavy corn diet. Called also nicotinic acid, vitamin PP. See also nicotinamide.
- n. nutritional deficiency — causes hemorrhagic diarrhea, dermatitis, anemia and a severe stomatitis with ulceration of the mouth and tongue (‘black tongue’). In cats, the signs are diarrhea, emaciation and death. Called also pellagra.
- n. production — a test for differentiating Mycobacteria tuberculosis (positive) and M. avium (negative).
| Wikipedia: Niacin |
This article is about the organic compound and vitamin. For the band, see Niacin (band).
| Niacin | |
|---|---|
 |
 |
| IUPAC name |
nicotinic acid
|
| Other names | pyridine-3-carboxylic acid, nicotinic acid, nicotinamide, niacinamide, vitamin B3 |
| Identifiers | |
| CAS number | 59-67-6  |
| PubChem | 938 |
| MeSH | Niacin |
| SMILES |
C1=CC(=CN=C1)C(=O)O
|
| ChemSpider ID | 913 |
| Properties | |
| Molecular formula | C6H5NO2 |
| Molar mass | 123.11 g/mol |
| Melting point |
236.6 °C, 510 K, 458 °F |
| Boiling point |
decomposes |
| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
Niacin, also known as vitamin B3 or nicotinic acid, is an organic compound with the formula C5H4NCO2H. This colourless, 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.
Niacin is converted to nicotinamide and then to NAD and NADP in vivo. Although the two are identical in their vitamin activity, nicotinamide does not have the same pharmacological effects as niacin, which occur as side-effects of niacin's conversion. Nicotinamide does not reduce cholesterol or cause flushing.[1] Nicotinamide may be toxic to the liver at doses exceeding 3 g/day for adults.[2] Niacin is a precursor to NADH, NAD+, NADP+ and NADPH, which play essential metabolic roles in living cells.[3] Niacin is involved in both DNA repair, and the production of steroid hormones in the adrenal gland.
Niacin is one of five vitamins associated with a pandemic deficiency disease: these are niacin (pellagra), vitamin C (scurvy), thiamin (beriberi), vitamin D (rickets), and vitamin A deficiency, a syndrome which has no common name but is one of the most common symptomatic deficiencies worldwide.
Contents |
History
Niacin was first described by Hugo Weidel in 1873 in his studies of nicotine.[4] The original preparation remains useful: the oxidation of nicotine using nitric acid.[5] Niacin was extracted from livers by Conrad Elvehjem who later identified the active ingredient, then referred to as the "pellagra-preventing factor" and the "anti-blacktongue factor."[6] When the biological significance of nicotinic acid was realized, it was thought appropriate to choose a name to dissociate it from nicotine, to avoid the perception that vitamins or niacin-rich food contains nicotine, or that cigarettes contain vitamins. The resulting name 'niacin' was derived from nicotinic acid + vitamin.
Carpenter found in 1951 that niacin in corn is biologically unavailable, and can only be released in very alkaline lime water of pH 11.[7] This process is known as nixtamalization.[8]
Niacin is referred to as Vitamin B3 because it was the third of the B vitamins to be discovered. It has historically been referred to as "vitamin PP."
Dietary needs
Main article: Pellagra
Depending on the definition used, niacin is one of between 40 to 80 essential human nutrients.
Currently, niacin deficiency is rarely seen in developed countries and is usually apparent in conditions of poverty and malnutrition and chronic alcoholism. Alcoholic patients typically experience increased intestinal permeability leading to negative health outcomes. Studies have indicated that in patients with alcoholic pellagra, niacin deficiency may be an important factor influencing both the onset and severity of this condition . Severe deficiency of niacin in the diet causes the disease pellagra. Pellagra is characterized by diarrhea, dermatitis and dementia as well as “necklace” lesions on the lower neck, hyperpigmentation, thickening of the skin, inflammation of the mouth and tongue, digestive disturbances, amnesia, delirium, and eventually death, if left untreated (Prakash et al., 2008). Common psychiatric symptoms of niacin deficiency include irritability, poor concentration, anxiety, fatigue, restlessness, apathy, and depression (Prakash et al., 2008). Mild niacin deficiency has been shown to slow metabolism, causing decreased tolerance to the cold. Dietary niacin deficiency tends to occur in areas where people eat maize ("corn") as a staple food. Maize is the only grain low in niacin, and nixtamalization is needed to increase the bioavaiability of niacin during meal/flour production. Nixtamalization refers to the process of cooking maize with alkaline lime. This is the primary processing step during the manufacture of maize products, including chips, tortillas, and taco shells. The basic pre-Columbian technique involves cooking whole maize in water for 12–16 hours in large tanks. The steeped maize is referred to as nixtamal, and the cooked liquid is nejayote. This process functions to soften the pericarp of the maize, and allows the endosperm to absorb water, enabling its milling. The nixtamal is washed and then stone-ground to produce masa, which is used to produce a variety of products with improved bioavailability of niacin (Sefa-Dedeh et al., 2004).
The recommended daily allowance of niacin is 2–12 mg/day for children, 14 mg/day for women, 16 mg/day for men, and 18 mg/day for pregnant or breast-feeding women.[9] The upper limit for adult men and women is 35 mg/day which is based on flushing as the critical adverse effect, this dose-dependent flushing effect consists of a single episode 10 to 20 minutes after niacin is taken. However, it has been reported anecdotally by some as a pleasant feeling.
Hartnup’s disease is an heretitary nutritional disorder resulting in niacin deficiency<--(Prakash et al., 2008)-->. This condition was first identified in the 1950’s by the Hartnup family in London. It is due to a deficit in the intestines and kidneys, making it difficult for the body to break down and absorb dietary tryptophan. The resulting condition is similar to pellagra, including symptoms of red, scaly rash and sensitivity to sunlight. Oral niacin is given as a treatment for this condition in doses ranging from 40-200 mg with a good prognosis if identified and treated early. Niacin synthesis is also deficient in carcinoid syndrome, because of metabolic diversion of its precursor, tryptophan, to form serotonin.
Niacin status is generally tested through urinary biomarkers,[10] which are believed to be more reliable than plasma levels.[11]
Lipid modifying effects
In pharmacological doses, niacin has been proven to reduce total cholesterol, triglyceride, very-low-density lipoprotein, low-density lipoprotein, and increase high-density lipoprotein levels. Niacin, prescribed in doses between 1000 and 2000 mg two to three times daily,[12] blocks the breakdown of fats in adipose tissue, more specifically the very-low-density lipoprotein (VLDL), 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.[13]
By lowering VLDL levels, niacin also increases the level of high-density lipoprotein (HDL) or "good" cholesterol in blood, and therefore it is sometimes prescribed for patients with low HDL, who are also at high risk of a heart attack.[14][15]
As of August 2008[update], a combination of niacin with laropiprant is tested in a clinical trial. Laropiprant reduces facial flushes induced by niacin. [16] Taking 650 mg of aspirin 20-30 minutes prior to taking niacin has also been proven to prevent flushing in 90% of patients, presumably by suppressing prostaglandin synthesis,[2] and while this regimen also increases the risk of gastrointestinal bleeding,[3] the increased risk is less than 1 percent. [4]
A clinical study, results of which were presented at the 2009 annual meeting of the American Heart Association and published in the New England Journal of Medicine suggest that in combination with statins, Niaspan, a form of niacin, is more effective than Zetia at reducing arterial buildup.[17]
Anti-Alzheimer's symptomatic effects
Vitamin B3 has been reported to prevent Alzheimer's-like symptoms in a mouse model of the disease.[18]
Oily skin
Clinical trials using niacinamide topically have demonstrated a decrease in sebum output by the face epithelial cells, helping in the treatment of acne and related affections. Anecdotally there have been reports of successful control in cases of excessive output of sebum using dietary supplementation of Niacin (the flushing kind) at a dosage of 500mg to 1000mg a day.
Toxicity
Pharmacological doses of niacin (1.5 - 6 g per day) often lead to side-effects that can include dermatological complaints such as skin flushing and itching, dry skin, skin rashes including acanthosis nigricans. Gastrointestinal complaints, such as dyspepsia (indigestion) and liver toxicity (fulminant hepatic failure) have also been reported. Side effects of hyperglycemia, cardiac arrhythmias and birth defects have also been reported.[19][20] The flush lasts for about 15 to 30 minutes, and is sometimes accompanied by a prickly or itching sensation, particularly in areas covered by clothing. This effect is mediated by prostaglandin and can be blocked by taking 300 mg of aspirin half an hour before taking niacin, or by taking one tablet of ibuprofen per day. Taking the niacin with meals also helps reduce this side effect. After several weeks of a consistent dose, most patients no longer flush.[21] Slow- or "sustained"-release forms of niacin have been developed to lessen these side-effects.[13][22] One study showed the incidence of flushing was significantly lower with a sustained release formulation[23] though doses above 2 g per day have been associated with liver damage, particularly with slow-release formulations.[19] Flushing is often thought to involve histamine, but histamine has been shown not to be involved in the reaction.[24] Prostaglandin (PGD2) is the primary cause of the flushing reaction, serotonin appears to have a secondary role in this reaction.[24]
High-dose niacin may also elevate blood sugar, thereby worsening diabetes mellitus.[19]
Hyperuricemia is another side-effect of taking high-dose niacin, and may exacerbate gout.[25]
Niacin at doses used in lowering cholesterol has been associated with birth defects in laboratory animals, with possible consequences for infant development in pregnant women.[19]
Niacin at extremely high doses can have life-threatening acute toxic reactions.[26] 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.[27]
Inositol hexanicotinate
One popular form of dietary supplement is inositol hexanicotinate, usually sold as "flush-free" or "no-flush" niacin in units of 250, 500 or 1000 mg/tablet or capsule. While this form of niacin does not cause the flushing associated with the immediate release products, the evidence that it has lipid modifying functions is contradictory, at best. As the clinical trials date from the early 1960s (Dorner, Welsh) or the late 1970s (Ziliotto, Kruse, Agusti) it is difficult to assess them by today's standards.[28] A more recent placebo-controlled trial was small (n=11/group), but results after three months at 1500 mg/day showed no trend for improvements in total cholesterol, LDL-C, HDL-C or triglycerides (AM Benjo; Atherosclerosis 2006;187:116-122). Thus, so far there is not enough evidence to recommend inositol hexanicotinate to treat dyslipidemia. Furthermore, the American Heart Association and the National Cholesterol Education Program both take the position that only prescription niacin should be used to treat dyslipidemias, and only under the management of a physician. The reason given is that niacin at effective intakes of 1500-3000 mg/day can also potentially have severe adverse effects. Monitoring of liver enzymes is necessary.
Biosynthesis and chemical synthesis
The liver can synthesize niacin from the essential amino acid tryptophan, requiring 60 mg of tryptophan to make one mg of niacin.[29] The 5-membered aromatic heterocycle of tryptophan is cleaved and rearranged with the alpha amino group of tryptophan into the 6-membered aromatic heterocycle of niacin.
Several million kilograms of niacin are manufactured each year, starting from 3-methylpyridine.
Receptor
The receptor for niacin is a G protein-coupled receptor called HM74A.[30] It couples to Gi alpha subunit.[31]
Food sources
Niacin is found in variety of foods including liver, chicken, beef, fish, cereal, peanuts and legumes and is also synthesized from tryptophan, which is found in meat, dairy and eggs. In order to convert 1 mg of niacin, 60 mg of tryptophan is required.
Animal products:
Fruits and vegetables:
Seeds:
Fungi:
References
- ^ Jaconello P (October 1992). "Niacin versus niacinamide". CMAJ 147 (7): 990. PMID 1393911.
- ^ Knip M, Douek IF, Moore WP, et al. (2000). "Safety of high-dose nicotinamide: a review". Diabetologia 43 (11): 1337–45. doi:. PMID 11126400.
- ^ Cox, Michael; Lehninger, Albert L; Nelson, David R. (2000). Lehninger principles of biochemistry. New York: Worth Publishers. ISBN 1-57259-153-6.
- ^ Weidel, H (1873). "Zur Kenntniss des Nicotins". Justus Liebig's Annalen der Chemie und Pharmacie 165: 330–349. doi:.
- ^ Samuel M. McElvain (1941), "Nicotinic Acid", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV1P0385.pdf; Coll. Vol. 1: 385
- ^ Elvehjem, C.A.; Madden, R.J.; Strongandd, F.M.. "W. WOOLLEY 1938 The isolation and identification of the anti-blacktongue factor J". J. Biol. Chem 123: 137.
- ^ LAGUNA J, CARPENTER KJ (September 1951). "Raw versus processed corn in niacin-deficient diets". J. Nutr. 45 (1): 21–8. PMID 14880960. http://jn.nutrition.org/cgi/pmidlookup?view=long&pmid=14880960.
- ^ "Vitamin B3". University of Maryland Medical Center. 2002-01-04. http://www.umm.edu/altmed/articles/vitamin-b3-000335.htm. Retrieved 2008-03-31.
- ^ United States Department of Agriculture, National Agriculture Library, Food and Nutrition Information Center, Dietary Reference Intakes: Recommended Intakes for Individuals, Vitamins [1]
- ^ Institute of Medicine. (2006). Dietary Reference Intakes Research Synthesis: Workshop Summary, p. 37. National Academies Press.
- ^ Jacob RA, Swendseid ME, McKee RW, Fu CS, Clemens RA (April 1989). "Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites". J. Nutr. 119 (4): 591–8. PMID 2522982. http://jn.nutrition.org/cgi/pmidlookup?view=long&pmid=2522982.
- ^ Marks, Jay W. (2005). "Niacin Monograph". MedicineNet, Inc..
- ^ a b Katzung, Bertram G. (2006). Basic and clinical pharmacology. New York: McGraw-Hill Medical Publishing Division. ISBN 0071451536. http://www.medicinenet.com/niacin/article.htm.
- ^ McGovern ME (2005). "Taking aim at HDL-C. Raising levels to reduce cardiovascular risk". Postgrad Med 117 (4): 29–30, 33–5, 39 passim. PMID 15842130.
- ^ Canner PL, Berge KG, Wenger NK, et al. (1986). "Fifteen year mortality in Coronary Drug Project patients: long-term benefit with niacin". J. Am. Coll. Cardiol. 8 (6): 1245–55. PMID 3782631.
- ^ Paolini JF, Bays HE, Ballantyne CM, et al. Extended-release niacin/laropiprant: reducing niacin-induced flushing to better realize the benefit of niacin in improving cardiovascular risk factors. Cardiol Clin. 2008 Nov;26(4):547-60.
- ^ Singer, Natasha (November 15, 2009). "Study Raises Questions About Cholesterol Drug’s Benefit". The New York Times. http://www.nytimes.com/2009/11/16/health/research/16heart.html. Retrieved November 16, 2009.
- ^ Green, Kim N.; Joan S. Steffan, Hilda Martinez-Coria, Xuemin Sun, Steven S. Schreiber, Leslie Michels Thompson, and Frank M. LaFerla (November 5, 2008). "Nicotinamide Restores Cognition in Alzheimer's Disease Transgenic Mice via a Mechanism Involving Sirtuin Inhibition and Selective Reduction of Thr231-Phosphotau". The Journal of Neuroscience 28 (45): 11500–11510. doi:. PMID 18987186. PMC 2617713. http://www.jneurosci.org/cgi/content/abstract/28/45/11500. Retrieved January 20, 2009.
- ^ a b c d Keith Parker; Laurence Brunton; Goodman, Louis Sanford; Lazo, John S.; Gilman, Alfred (2006). Goodman & Gilman's the pharmacological basis of therapeutics. New York: McGraw-Hill. ISBN 0071422803.
- ^ McGee, W (2007-02-01). "Medical Encyclopedia: Niacin". MedlinePlus. http://www.nlm.nih.gov/medlineplus/ency/article/002409.htm. Retrieved 2008-03-31.
- ^ "Guidelines for Niacin Therapy For the Treatment of Elevated Lipoprotein a (Lpa)". Rush Hemophilia & Thrombophilia Center. August 15, 2002, Revised July 27, 2005. http://www.rush.edu/Rush_Document/Niacin%20therapy%20for%20elevated%20Lpa,0.pdf. Retrieved 20 November 2009. "facial flushing is a common side effect of niacin therapy that usually subsides after several weeks of consistent niacin use"
- ^ Barter, P (2006). "Options for therapeutic intervention: How effective are the different agents?". European Heart Journal Supplements 8 (F): F47–F53. doi:.
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| Translations: Niacin |
Dansk (Danish)
n. - nikotinsyre
Nederlands (Dutch)
niacine/ nicotinezuur (vitamine B5)
Français (French)
n. - acide nicotinique
Deutsch (German)
n. - (chem.) Nikotinsäure
Ελληνική (Greek)
n. - νικοτινικό οξύ
Português (Portuguese)
n. - ácido (m) nicotínico (Biol.)
Русский (Russian)
никотиновая кислота
Español (Spanish)
n. - niacina, ácido nicotínico
Svenska (Swedish)
n. - nikotinsyra, niacin
中文（简体）(Chinese (Simplified))
烟碱酸的商品名, 尼亚新
中文（繁體）(Chinese (Traditional))
n. - 煙鹼酸的商品名, 尼亞新
العربيه (Arabic)
(الاسم) الحامض النيكوتيني
עברית (Hebrew)
n. - ניאצין (ויטמין\חומצה)
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Mentioned in
- nicotinic acid
- niacinamide
- pellagra
- congie
- niacinogens
- niceritol
- vitamin B3
- vitamin PP
- blacktongue (veterinary medicine)
- Pellegra (in medicine)
