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Vitamin B3 (Niacin)

Vitamin B3, or niacin, is a member of the B-vitamin family. It is water-soluble, which means it is not stored in your body and needs to be frequently replenished. There are two forms of vitamin B3, niacin (also known as nicotinic acid) and niacinamide (also known as nicotinamide). Both forms work the same way as an important nutrient in your body, but are used to treat different conditions.

Your body needs vitamin B3 to turn carbohydrates into energy. Without B3, your body systems would grind to a halt. B3 is also involved in the breakdown of fat and cholesterol, which is why niacin (nicotinic acid) has been found to be a good cholesterol-lowering agent.

Your body uses vitamin B3 to make various compounds, such as sex hormones and adrenal hormones. It can also help the body get rid of toxic and harmful chemicals, and it helps with blood sugar control.

Most people get enough of this vitamin just from the foods they eat. Your health care provider may prescribe a vitamin B3 supplement for high cholesterol or other conditions. It is important that your health care provider closely monitors you while you are taking high doses of vitamin B3 because it can cause serious side effects, such as liver damage, at these dosages.


Niacin reduces LDL (bad) cholesterol and increases HDL (good) cholesterol. It can also enhance the effect of prescription cholesterol-lowering drugs. Use it for this purpose only under the close supervision of a health care provider.

Niacinamide can help treat osteoarthritis and rheumatoid arthritis, insulin-dependent diabetes, insomnia, and migraine headaches.

Either form may be used to treat or prevent vitamin B3 deficiency (pellagra). People with cancer or tuberculosis, women who take oral contraceptives (birth control pills), and people suffering from protein deficiencies are more likely to have vitamin B3 deficiency.

Dietary Sources

Our bodies actually manufacture vitamin B3 from protein, so if you are eating enough protein, you will also be getting enough vitamin B3. The best sources of vitamin B3 are found in protein-rich foods such as lean meats, chicken, fish, eggs, cooked dried beans and peas, liver, nonfat or lowfat milk and cheese, soybeans, and nuts.

Other good sources include brewer's yeast, wheat germ, enriched breads and cereals, whole grains (except corn), mushrooms, and green vegetables. Vitamin B3 can be lost in cooking water, so you should steam, bake, or stir-fry vegetables when possible.

Other Forms

If your health care provider advises you to take extra vitamin B3, you can purchase niacin or niacinamide supplements in a variety of forms, including tablets in strengths of 25 mg, 50 mg, 100 mg, 250 mg, and 500 mg. Although timed-release tablets and capsules are available, and have advantages, there are studies showing that timed-release niacin may cause liver damage. Niacin is also available as inositol hexaniacinate, a preparation developed in Europe. Inositol hexaniacinate is a sustained-release delivery method that is not thought to lead to liver disorders.

How to Take It

It is important to take niacin supplements with food to avoid stomach upset and to decrease the risk of developing stomach ulcers.


High doses (75 mg or more) of niacin can cause side effects. The most common side effect is called "niacin flush." You may feel a burning, tingling sensation in your face and chest, and your skin will get red or "flushed." It is harmless unless you have asthma; so people with asthma should not take niacin supplements at high dosages. At very high doses like those used to lower cholesterol, liver damage and stomach ulcers can occur. If you have had liver disease or stomach ulcers, you should not take niacin supplements. If you have diabetes, gallbladder disease, or gout, you can take supplements under the close supervision of your health care provider.

Possible Interactions

Aspirin (acetylsalicylic acid) prolongs the length of time that niacin is in the body.

Niacin affects a class of cholesterol-lowering medications called bile-acid sequestrants (such as colestipol and cholestyramine); therefore, niacin and these medications should be taken at different times of the day. When niacin is taken at the same time as certain cholesterol-lowering medications, the likelihood for adverse effects, such as muscle inflammation or liver toxicity, is increased.

When niacin is taken with certain blood pressure medications (such as prazosin, doxazosin, and guanabenz), the likelihood for side effects from these medications is increased.

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