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Niacin (vitamin B3)
What is
niacin?
Niacin, a white crystalline substance, belongs to the B-vitamin
group. A water-soluble vitamin, it is absorbed in the intestines
and carried throughout the body in the bloodstream. After
the body uses what it needs, any excess niacin is excreted
in urine.
Why do
we need it?
Niacin helps break down blood sugar for energy. It also acts
as a vasodilator, widening blood vessels and helping increase
blood flow. Some health experts have prescribed niacin supplements
for helping people lower high cholesterol or triglyceride
levels; it thus plays a major role in protecting against cardiovascular
disease.
How much
niacin should I take?
According to the National Academy of Sciences, the recommended
daily allowance (RDA) for niacin is as follows:
- Adult men: 19 milligrams/day
- Adult women: 15 milligrams/day
- Children aged 7-10: 13 milligrams/day
- Infants: 6 milligrams/day
- Pregnant/lactating women: 19 milligrams/day.
What are
some good sources of niacin?
One of the best sources of niacin is fish, particularly mackerel
and swordfish. Niacin can also be found in chicken, veal,
pork, salmon, milk, eggs, fortified cereals, avocados, and
some nuts.
What can
happen if I don't get enough niacin?
Niacin deficiency causes pellagra, a chronic disease characterized
by skin eruptions, digestive and nervous disturbances and
mental deterioration. The condition can usually be reversed
by taking niacin supplements.
Anemia may also occur as a result of low niacin levels, although
this is usually due to an accompanying deficiency in folic
acid.
What can
happen if I take too much?
Niacin toxicity can lead to a variety of conditions. Even
mildly high doses can cause a dilation of the blood vessels
and lead to a potentially painfully tingling about the face
and shoulders called the "niacin flush," as well
as headaches, itchiness and stomach problems. Larger doses
may cause diarrhea, nausea, ulcers, gout, diabetes and in
rare cases, liver damage. Most of these conditions (with the
exception of liver damage) can usually be reversed by discontinuation
of high doses.
Other Resources :
The
More You Know About Vitamins
The
More You Know About Nutrition
References
• DSHP therapeutic
position statement on the safe use of niacin in the management
of dyslipidemias. American Society of Health System Pharmacists.
Am J Health Syst Pharm Dec. 15, 1997;54(24):2815-9.
• Guyton JR. Effect of niacin on atherosclerotic cardiovascular
disease. Am J Cardiol Dec. 17, 1998;82(12A):18U-23U.
• 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
March 2, 1994;271(9):672-7.
• Recommended Dietary Allowances, 10th ed. Washington,
D.C.: National Academy Press.
• Brown BG, et al. Moderate dose, three-drug therapy
with niacin, lovastatin, and colestipol to reduce low-density
lipoprotein cholesterol <100 mg/dl in patients with hyperlipidemia
and coronary artery disease. Am J Cardiol July 15,
1997;80(2):111-5.
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