Also indexed as: Inositol Hexaniacinate, Niacin, Niacinamide,
Nicotinamide, Nicotinic Acid
The body uses the water-soluble vitamin B3 in the process of releasing energy from
carbohydrates. It is needed to form fat from carbohydrates and to process alcohol. The niacin
form of vitamin B3 also regulates cholesterol,
though niacinamide does not.
Vitamin B3 has been used
in connection with the following conditions (refer to the individual
health concern for complete information):
Who is likely to be deficient?
Pellagra, the disease caused by a vitamin B3 deficiency, is rare in Western societies.
Symptoms include loss of appetite, skin rash,
diarrhea, mental changes, beefy tongue, and digestive and emotional disturbance.
How much is usually taken?
In part because it is added to white flour,
most people generally get enough vitamin B3 from their diets to prevent a deficiency. However,
10–25 mg of the vitamin can be taken as part of a B-complex or multivitamin supplement. Larger amounts are used for
the treatment of various health conditions.
Are there any side effects or interactions?
Niacinamide is almost always safe to take, though rare liver problems have occurred at
amounts in excess of 1,000 mg per day. Niacin, in amounts as low as 50–100 mg, may cause
flushing, headache, and stomachache in some
people. Doctors sometimes prescribe very high amounts of niacin (as much as 3,000 mg per day
or more) for certain health problems. These large amounts can cause liver damage, diabetes,
gastritis, damage to eyes, and elevated blood levels of uric acid (which can cause gout). Symptoms caused by niacin supplements,
such as flushing, have been reduced with sustained-release (also called
‘time-release’) niacin products. However, sustained-release forms of niacin have
caused significant liver toxicity and, rarely, liver failure.1 2
3 4 5 One partial time-release (intermediate-release) niacin
product has demonstrated clinical efficacy without flushing, and also without the liver
function abnormalities typically associated with sustained-release niacin
formulations.6 However, this form of niacin is available by prescription only.
In a controlled clinical trial, 1,000 mg or more per day of niacin raised blood levels of
homocysteine, a substance associated with
increased risk of heart disease.7
Since other actions of niacin lower heart disease risk,8 9 the
importance of this finding is unclear. Nonetheless, for all of the reasons discussed above,
large amounts of niacin should never be taken without consulting a doctor.
The inositol hexaniacinate form of niacin has not been linked with the side effects
associated with niacin supplementation. In a group of people being treated alternatively with
niacin and inositol hexaniacinate for skin problems, niacin supplementation (50–100 mg
per day) was associated with numerous side effects, including skin flushing, nausea, vomiting
and agitation.10 In contrast, people taking inositol hexaniacinate experienced no
complaints whatsoever, even at amounts two to five times higher than the previously used
amounts of niacin. However, the amount of research studying the safety of inositol
hexaniacinate remains quite limited. Therefore, people taking this supplement in large amounts
(2,000 mg or more per day) should be under the care of a doctor.
Vitamin B3 works with vitamin B1 and vitamin B2 to release energy from carbohydrates.
Therefore, these vitamins are often taken together in a B-complex or multivitamin supplement (although most B3 research
uses niacin or niacinamide alone).
Are there any drug
Certain medicines may interact with vitamin B3. Refer to drug interactions for a list of those medicines.
1. McKenney JM, Proctor JD, Harris S, Chinchili VM. A comparison of the
efficacy and toxic effects of sustained—vs immediate-release niacin in
hypercholesterolemic patients. JAMA 1994;271:672–7.
2. Knopp RH, Ginsberg J, Albers JJ, et al. Contrasting effects of
unmodified and time-release forms of niacin on lipoproteins in hyperlipidemic subjects: clues
to mechanism of action of niacin. Metabolism 1985;34:642–50.
3. Gray DR, Morgan T, Chretien SD, Kashyap ML. Efficacy and safety of
controlled-release niacin in dyslipoproteinemic veterans. Ann Intern Med
4. Rader JI, Calvert RJ, Hathcock JN. Hepatic toxicity of unmodified and
time-release preparations of niacin. Am J Med 1992;92:77–81 [Review].
5. Knopp RH. Niacin and hepatic failure. Ann Intern Med
6. Goldberg A, Alagona P Jr, Capuzzi DM, et al. Multiple-dose efficacy
and safety of an extended-release form of niacin in the management of hyperlipidemia. Am J
7. Garg R, Malinow M, Pettinger M, Upson B, Hunninghake D. Niacin
treatment increases plasma homocyst(e)ine levels. Am Heart J
8. Brown WV. Niacin for lipid disorders. Postgrad Med
9. Guyton JR. Effect of niacin on atherosclerotic cardiovascular disease.
Am J Cardiol 1998;82(12A):18U–23U [review].
10. Welsh AL, Ede M. Inositol hexanicotinate for improved nicotinic acid
therapy. Int Record Med 1961;174:9–15.