Vitamin B3 is one of 8 B vitamins, all of which are water-soluble, meaning that the body does not store them. It is also known as niacin (nicotinic acid) and has 2 other forms, niacinamide (nicotinamide) and inositol hexanicotinate, which have different effects from niacin.
All B vitamins help the body to convert carbohydrates into fuel (glucose), which is used to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body use fats and protein.
B complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly.
Niacin also helps the body make various sex and stress related hormones in the adrenal glands and other parts of the body as well as improve circulation.
In the United States, alcoholism is the main cause of vitamin B3 deficiency. Symptoms of mild deficiency include indigestion, fatigue, canker sores, vomiting, and depression. Severe deficiency can cause a condition known as pellagra. Pellagra is characterized by cracked, scaly skin, dementia, and/or diarrhea. It is generally treated with a nutritionally balanced diet and niacin supplements. Niacin deficiency also causes burning in the mouth and a swollen, bright red tongue.
Medical grade and high doses of B3 have been studied to prevent or improve symptoms of the following conditions.
The best food sources of vitamin B3 are found in beets, brewer’s yeast, beef liver, beef kidney, fish, salmon, swordfish, tuna, sunflower seeds, and peanuts. In addition, foods that contain tryptophan, an amino acid the body coverts into niacin with the help of vitamin B6, include poultry, red meat, eggs, and dairy products.
BEST AS SUPPLEMENT
Vitamin B3 as niacin, niacin USP, and 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 regular niacin. However, the timed-release versions are more likely to cause liver damage if taken at high doses for long periods of time. Regardless of which form of niacin you’re using, doctors recommend periodic liver function tests when using high doses (above 100 mg per day) of niacin.
INTERACTIONS WITH MEDICATIONS
High doses (50 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.
People with a history of liver disease, kidney disease, or stomach ulcers should not take niacin supplements. Those with diabetes or gallbladder disease should do so only under the close supervision of their doctor.
Stop taking niacin at least two weeks before a scheduled surgery.
Niacin may make allergies worse by increasing histamine.
People with low blood pressure should not take niacin because it may cause a dangerous drop in blood pressure. Don’t take niacin if you have a history of gout.
People with coronary artery disease or unstable angina should not take niacin without their doctor’s supervision, as large doses can raise the risk of heart rhythm problems.
Taking any one of the B vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, you may want to take a B complex vitamin, which includes all the B vitamins.
If you are currently taking any of the following medications, you should not use niacin without first talking to your health care 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. All vitamin B complex supplements act in this way and should be taken at different times from tetracycline.
Anti-seizure Medications — Phenytoin (Dilantin) and valproic acid (Depakote) may cause niacin deficiency in some people. Taking niacin with carbamazepine (Tegretol) or mysoline (Primidone) may increase levels of these medications in the body.
Anticoagulants (blood thinners) — Niacin may make the effects of these medications stronger, increasing the risk of bleeding.
Blood Pressure Medications, Alpha-blockers — Niacin can make the effects of medications taken to lower blood pressure stronger, leading to the risk of low blood pressure.
Cholesterol-lowering Medications — Niacin binds the cholesterol lowering medications known as bile-acid sequestrants and may make them less effective. For this reason, niacin and these medications should be taken at different times of the day. Bile-acid sequestrants include colestipol (Colestid), colesevelam (Welchol), and cholestyramine (Questran).
Statins — Some scientific evidence suggests that taking niacin with simvastatin (Zocor) appears to slow down the progression of heart disease. However, the combination may also increase the likelihood for serious side effects, such as muscle inflammation or liver damage.
Diabetes Medications — Niacin may increase blood sugar levels. People taking insulin, metformin (Glucophage), glyburide (Dibeta, Micronase), glipizide (Glucotrol), or other medications used to treat high blood glucose levels should monitor their blood sugar levels closely when taking niacin supplements.
Isoniazid (INH) — INH, a medication used to treat tuberculosis, may cause a niacin deficiency.
Nicotine Patches — Using nicotine patches with niacin may worsen or increase the risk of flushing associated with niacin.
These medications may lower levels of niacin in the body:
- Azathioprine (Imuran)
- Chloramphenicol (Chloromycetin)
- Cycloserine (Seromycin)
- Levodopa and carbidopa
- Mercaptopurine (Purinethol)
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