Vitamin B3, also called niacin, is one of eight water-soluble B vitamins. All
B vitamins help the body to convert carbohydrates into glucose (sugar), which is
"burned" to produce energy. These B vitamins, often referred to as B complex
vitamins, are essential in the breakdown of fats and protein. B complex vitamins
also play an important role in maintaining muscle tone along the digestive tract
and promoting the health of the nervous system, skin, hair, eyes, mouth, and
Niacin plays an important role in ridding the body of toxic and harmful
chemicals. It also helps the body make various sex and stress-related hormones
in the adrenal glands and other parts of the body. Niacin is effective in
improving circulation and reducing cholesterol levels in the blood. Niacin needs
can be partially met by eating foods containing protein because the human body
is able to convert tryptophan, an amino acid, into niacin.
Dietary deficiency of niacin tends to only occur in areas of the world where
people eat corn as a staple and don't use lime in fertilization. Corn is the
only grain that is low in niacin. Lime releases tryptophan which, again, can be
converted to niacin in the body. Symptoms of mild deficiency include
indigestion, fatigue, canker sores, vomiting, and depression. Severe deficiency
of both niacin and tryptophan can cause a condition known as pellagra. Pellagra
is characterized by cracked, scaly skin, dementia, and diarrhea. It is generally
treated with a nutritionally balanced diet and niacin supplements. Niacin
deficiency also results in burning in the mouth and a swollen, bright red tongue
In the United States alcoholism is the prime cause of Vitamin B3
Extremely high doses of niacin (available by prescription) have been shown to
prevent and/or improve symptoms of the following conditions. Because of risk of
toxicity people should always consult a knowledgeable health care provider
before starting high doses of niacin.
High Cholesterol Niacin is commonly used to lower elevated LDL
("bad") cholesterol and triglyceride (fat) levels in the blood and is more
effective in increasing HDL ("good") levels than other cholesterol-lowering
medications. However. High doses of niacin produce the side effects of flushing
of the skin (which can be reduced by taking aspirin 30 minutes before the
niacin), stomach upset (which usually subsides in a few weeks), headache,
dizziness, blurred vision, and liver damage. Although the time-release form of
niacin reduces flushing, long-term use is associated with liver damage.
Atherosclerosis High doses of niacin medications are used to
prevent development of atherosclerosis (plaque along the blood vessels that can
cause blockage) and to reduce recurrent complications such as heart attack and
peripheral vascular disease (atherosclerosis of the blood vessels in the legs
that can cause pain with walking, called intermittent claudication) in those
with the condition. According to a review of major clinical trials, the use of
niacin for prevention and treatment of atherosclerosis and related conditions is
"based on strong and consistent evidence" and appears to be as effective as
certain medications for heart disease. Studies also suggest that high dose
niacin may help relieve the symptoms of claudication -
namely diminish the pain experienced with walking.
A recent study also found that the combination of niacin and a
cholesterol-lowering drug called simvastatin (which belongs to a class known as
HmG CoA reductase inhibitors or statins) may dramatically slow the progression
of heart disease, reducing risk of heart attack, and even death.
Diabetes Because diabetes is often associated with
atherosclerosis and heart disease, people with diabetes may benefit from
nutrients that help manage elevated cholesterol levels and high blood pressure.
Although niacin has been shown to boost HDL cholesterol and decrease
triglyceride and LDL levels, there has been some concern that it may also raise
blood sugar levels. In a recent study of 125 people with diabetes and 343 people
without the condition, high doses of niacin (roughly 3000 mg/day), increased
blood sugar in both groups, but hemoglobin A1C (considered a better measure of
blood sugar over time) actually decreased in the diabetes group over a 60-week
follow-up period. For this reason, if you have diabetes, niacin should only be
used under the close monitoring of a qualified health care provider.
Osteoarthritis Some preliminary studies suggest that vitamin
B3, as niacinamide, may improve arthritis symptoms, including increasing joint
mobility and reducing the amount of anti-inflammatory medications needed.
Researchers speculate that niacinamide may aid cartilage repair (damage to joint
cartilage causes arthritis) and suggest that it may be used safely along with
NSAIDs (non-steroidal anti-inflammatory medications) to reduce inflammation.
Further research is needed to fully understand how vitamin B3 benefits people
with OA and to determine whether the results apply to large numbers of people
with the condition. It does appear, however, that niacinamide must be used for
at least 3 weeks before the benefits described are seen. Experts also suggest
that long-term use (1 to 3 years) may slow the progression of the disease.
Cataracts Dietary vitamin B3, along with other nutrients is
important for normal vision and prevention of cataracts (damage to the lens of
the eye which can lead to cloudy vision.) One study including 2900 people living
in Australia found that people who consumed the most protein, vitamin A, and
vitamins B1 (thiamine), B2, and B3 (niacin) in their diets were significantly
less likely to develop cataracts. A follow-up study also found that many
supplemental B complex vitamins (including B12, B9, B3, B2, and B1) exert a
protective effect against cataracts.
Burns It is especially important for people who have sustained
serious burns to obtain adequate amounts of nutrients in their daily diet. When
skin is burned, a substantial percentage of micronutrients may be lost. This
increases the risk for infection, slows the healing process, prolongs the
hospital stay, and even increases the risk of death. Although it is unclear
which micronutrients are most beneficial for people with burns, many studies
suggest that a multivitamin including the B complex vitamins may aid in the
Other An interesting area of research currently underway is
the use of niacin skin care products as anti-aging agents, for treatment of
acne, and, possibly, for prevention of skin cancer. Dermatologists expect that
there will be information emerging about topical forms of niacin for these
purposes over the next few years.
The best dietary sources of vitamin B3 are found in beets, brewer's yeast,
beef liver, beef kidney, pork, turkey, chicken, veal, fish, salmon, swordfish,
tuna, sunflower seeds, and peanuts.
Niacin is available in several different supplement forms: niacinamide,
nicotinic acid, and inositol hexaniacinate. The form of niacin that is best
tolerated with the least symptoms is inositol hexaniacinate. Niacin is available
as a tablet or capsule in both regular and timed-release forms. The
timed-release tablets and capsules may have fewer side effects than the regular
niacin; however, the timed-release are more likely to cause liver damage and are
therefore not recommended for long-term treatment. Regardless of the form of
niacin being used, periodic checking of liver function tests is recommended when
high-dose (2 - 6 gm per day) of niacin is used.
How to Take It
Daily requirements for niacin may be higher for those who have cancer, those
who are being treated with isoniazid (for tuberculosis), and people with protein
Daily recommendations for niacin from the diet for healthy individuals are
It is important to note, however, that only extremely high doses of niacin
(in the range of 1,500 to 3,000 mg per day in divided doses) are helpful for
most medical conditions. Such high doses are considered "pharmacologic" and must
be prescribed by a qualified healthcare practitioner. The practitioner will
instruct you on increasing the amount of niacin slowly, over the course of 4 to
6 weeks, and to take the medicine with meals to avoid stomach irritation.
Infants birth to 6 months: 2 mg (adequate intake)
Infants 7 months to 1 year: 4 mg (adequate intake)
Children 1 to 3 years: 6 mg (RDA)
Children 4 to 8 years: 8 mg (RDA)
Children 9 to 13 years: 12 mg (RDA)
Males 14 to 18 years: 16 mg (RDA)
Females 14 to 18 years: 14 mg (RDA)
Males 19 years and older: 16 mg (RDA)
Females 19 years and older: 14 mg (RDA)
Pregnant females: 18 mg (RDA)
Breastfeeding females: 17 mg
Because of the potential for side effects and interactions with medications,
dietary supplements should be taken only under the supervision of a
knowledgeable healthcare provider.
High doses (75 mg or more) of niacin can cause side effects. The most common
side effect is called "niacin flush," which is a burning, tingling sensation in
the face and chest, and red or "flushed" skin. Taking an aspirin 30 minutes
prior to the niacin may help reduce this symptom.
At the very high doses used to lower cholesterol and the other conditions
mentioned previously, liver damage and stomach ulcers can occur. When taking
pharmacologic doses of niacin, your doctor or other healthcare practitioner will
periodically check your liver function through a blood test. People with a
history of liver disease or stomach ulcers should not take niacin supplements.
Those with diabetes or gallbladder disease should do so only under the close
supervision of a healthcare provider. Niacin should not be used if you have
Taking any one of the B complex vitamins for a long period of time can result
in an imbalance of other important B vitamins. For this reason, it is generally
important to take a B complex vitamin with any single B
If you are currently being treated with any of the following medications, you
should not use niacin without first talking to your healthcare provider.
Antibiotics, Tetracycline Niacin should not be taken at the
same time as the antibiotic tetracycline because it interferes with the
absorption and effectiveness of this medication. Niacin either alone or in
combination with other B vitamins should be taken at different times from
tetracycline. (All vitamin B complex supplements act in this way and should
therefore be taken at different times from tetracycline.)
Aspirin Taking aspirin before taking niacin may reduce
flushing associated with this vitamin. This should only be done under the advice
of a healthcare practitioner.
Blood Pressure Medications, Alpha-blockers When niacin is
taken with certain blood pressure medications known as alpha-blockers (such as
prazosin, doxazosin, and guanabenz), the likelihood of side effects from these
medications is increased.
Cholesterol-lowering Medications Niacin binds bile-acid
sequestrants (cholesterol-lowering medications such as colestipol, colesevelam,
and cholestyramine) and may decrease their effectiveness. For this reason,
niacin and these medications should be taken at different times of the day.
As described earlier, recent scientific evidence suggests that taking niacin
with simvastatin (a drug that belongs to a class of cholesterol-lowering
medications known as HMG-CoA reductase inhibitors or statins including
atorvastatin and lovastatin as well), appears to slow down the progression of
heart disease. However, the combination may also increases the likelihood for
serious side effects, such as muscle inflammation or liver damage.
Diabetes Medications People taking insulin, metformin,
glyburide, glipizide, or other medications used to treat high blood sugar levels
should monitor their blood sugar levels closely when taking niacin supplements.
Isoniazid (INH) INH, a medication used to treat tuberculosis,
may deplete levels of niacin and cause a deficiency.
Nicotine Patches The use of nicotine patches with niacin may
worsen or increase the risk of flushing reactions associated with this vitamin
when used medicinally.
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Review Date: April 2002
Reviewed By: Participants in the review process include: Jacqueline A. Hart, MD,
Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University
and Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh
(Pediatric Dosing section February 2001), Johnson Drugs, Natick, Ma; Steven
Ottariono, RPh (Pediatric Dosing section February 2001), Veteran's
Administrative Hospital, Londonderry, NH; Margie Ullmann-Weil, MS, RD,
specializing in combination of complementary and traditional nutritional
therapy, Boston, MA. All interaction sections have also been reviewed by a team
of experts including Joseph Lamb, MD (July 2000), The Integrative Medicine
Works, Alexandria, VA;Enrico Liva, ND, RPh (August 2000), Vital Nutrients,
Middletown, CT; Brian T Sanderoff, PD, BS in Pharmacy (March 2000), Clinical
Assistant Professor, University of Maryland School of Pharmacy; President, Your
Prescription for Health, Owings Mills, MD; Ira Zunin, MD, MPH, MBA (July 2000),
President and Chairman, Hawaii State Consortium for Integrative Medicine,
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