Niacin (Vitamin B3)

Having enough niacin, or vitamin B3, in the body is important for general good health. As a treatment, higher amounts of niacin can improve cholesterol levels and lower cardiovascular risks.

Why do people take niacin?

As a cholesterol treatment, niacin has strong evidence. Several studies have shown that it can boost levels of good HDL cholesterol and lower triglycerides as well or better than some prescription drugs. Niacin also modestly lowers bad LDL cholesterol. It's often prescribed in combination with statins for cholesterol control, such as Crestor, Lescol, or Lipitor.

However, niacin is only effective as a cholesterol treatment at fairly high doses. These doses could pose risks, such as liver damage, gastrointestinal problems, or glucose intolerance. So don't treat yourself with over-the-counter niacin supplements. Instead, get advice from your health care provider, who can prescribe FDA-approved doses of niacin instead.

Niacin has other benefits. There's good evidence that it helps reduce atherosclerosis, or hardening of the arteries in some people. For people who have already had a heart attack, niacin seems to lower the risk of a second one. In addition, niacin is an FDA-approved treatment for pellagra, a rare condition that develops from niacin deficiency.

Niacin has also been studied as a treatment for many other health problems. There's some evidence that it might help lower the risk of Alzheimer's disease, cataracts, osteoarthritis, and type 1 diabetes. However, more research needs to be done.

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How much niacin should you take?

Since niacin can be used in different ways, talk to your health care provider about the best dosage for you.

Everyone needs a certain amount of niacin -- from food or supplements -- for the body to function normally. This amount is called the dietary reference intake (DRI), a term that is replacing the older and more familiar RDA (recommended daily allowance). For niacin, the DRIs vary with age and other factors.

  • Children: between 2-16 milligrams daily, depending on age
  • Men: 16 milligrams daily
  • Women: 14 milligrams daily
  • Women (pregnant): 18 milligrams daily
  • Women (breastfeeding): 17 milligrams daily
  • Maximum daily intake for adults of all ages: 35 milligrams daily

However, the ideal dosage of niacin depends on how you're using it. For instance, much higher doses -- 2 to 3 grams or more -- are used to treat high triglycerides.

Since niacin can upset your stomach, you might want to take it with food. To reduce flushing, your health care provider might recommend taking niacin along with aspirin, an NSAID painkiller, or an antihistamine for a few weeks until tolerance to the niacin develops.

Can you get niacin naturally from foods?

Niacin occurs naturally in many foods, including greens, meat, poultry, fish, and eggs, though in a fraction of the dose shown to achieve changes in cholesterol. Many products are also fortified with niacin during manufacture.

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What are the risks of taking niacin?

  • Side effects. Niacin can cause flushing -- harmless but uncomfortable redness and warmth in the face and neck -- especially when you first begin taking it. Your health care provider will probably suggest increasing the dose slowly to reduce this problem. He or she might also offer a time-release prescription formulation to control flushing. Niacin can cause upset stomach and diarrhea. However, all of these side effects tend to fade over time.
  • Risks. Niacin does have risks. It can cause liver problems, stomach ulcers, changes to glucose levels, muscle damage, low blood pressure, heart rhythm changes, and other issues. People with any health condition including liver or kidney disease, diabetes, high blood pressure, or cardiovascular problems need to talk to a doctor before using niacin supplements. Do not treat high cholesterol on your own with over-the-counter niacin supplements.
  • Interactions. If you take any medicines or supplements regularly, talk to your doctor before you start using niacin supplements. They could interact with medicines like diabetes drugs, blood thinners, anticonvulsants, blood pressure medicines, thyroid hormones, and antibiotics as well as supplements like ginkgo biloba and some antioxidants. Alcohol might increase the risk of liver problems. Though niacin is often used along with statins for high cholesterol, this combination may increase the risk for side effects. Get advice from your health care provider.

At the low DRI doses, niacin is safe for everyone. However, at the higher amounts used to treat medical conditions, it can have risks. For that reason, children and women who are pregnant or breastfeeding should not take niacin supplements in excess of the DRI unless it's recommended by a doctor.

WebMD Medical Reference Reviewed by David Kiefer, MD on May 01, 2015

Sources

SOURCES:

Fundukian, L., ed. The Gale Encyclopedia of Alternative Medicine, third edition, 2009.

Natural Medicines Comprehensive Database: “Niacin.” 

Natural Standard Patient Monograph, “Niacin.”

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