Vitamin Watch: What Does B-3 Do?

Medically reviewed by Natalie Butler, RD, LD on June 21, 2016Written by Brian Krans

The essential vitamin B-3

Vitamin B-3, also known as niacin, is an essential nutrient for the body. It helps major organs function properly. It also helps the body repair DNA.

The recommended daily dose of vitamin B-3 for different groups varies:

  • 2 to 12 mg a day for children
  • 14 mg a day for women
  • 16 mg a day for men
  • 18 mg a day for pregnant women
  • 17 mg a day for women who are breast-feeding

People who consume too much B-3 often experience flushing of the skin. But this typically subsides in less than an hour.

Natural sources of vitamin B-3

Vitamin B-3 is found naturally in many foods, including fruits, vegetables, meat, and beer. Yes, beer! Brewer’s yeast is one of the most abundant sources. A pint of beer contains about 6 mg of B-3, but less if it’s filtered.

You can also try these niacin-rich foods:

  • Vegemite and Marmite
  • liver, heart, and kidney meats
  • chicken breast, fish, venison, and beef
  • dates
  • avocados
  • nuts
  • whole-grain bread products
  • shiitake mushrooms

Eating organ meats is one of the easiest ways to get a lot of vitamin B-3. And in addition to fruits, vegetables, and grains, vegetarians can find it in:

  • peanut butter
  • tofu
  • the nutritional drink Ovaltine

B-3 for the heart

According to the Mayo Clinic, vitamin B-3 can help reduce the risk of cardiovascular disease by boosting the amount of high-density lipoproteins (HDL), also known as “good” cholesterol.

However, the Mayo Clinic warns that B-3 isn’t for everyone trying to increase HDL. People who are already taking medications called statins to lower their cholesterol do not need to increase their intake of B-3.

While vitamin B-3 is available in food, it’s also available as a supplement. Niacor and Niaspan are medications for people with a vitamin B-3 deficiency or high levels of low-density lipoprotein cholesterol (LDL), considered “bad” cholesterol.

Other possible benefits of niacin

While some people believe that B-3 may help ward off diabetes, research remains inconclusive.

Increased vitamin B-3 intake may benefit people with compromised immune systems or who are at greater risk for heart disease. For example, people undergoing chemotherapy and people with HIV.

Symptoms of deficiency

People with low levels of vitamin B-3 can develop pellagra, a condition marked by “the four D’s:”

  • dermatitis
  • dementia
  • diarrhea
  • death

Pellagra can be treated with nicotinamide, or niacinamide, a form of niacin that’s less toxic in higher doses than B-3.

While pellagra is rare in more developed countries, less extreme forms of vitamin B-3 deficiency include:

  • lethargy
  • nausea
  • anemia
  • lesions on the skin or around the mouth
  • extreme sunlight sensitivity

Because B-3 plays a crucial role in making sure that major organs function properly, people often experience systemic and painful side effects from a deficiency.

Symptoms of excessive B-3

Too much B-3 can be toxic. Patients should discuss using the supplement form with their doctors first. There may be risks, especially if you are taking other medications.

The primary concern with too much B-3 is inflammation of the liver. For this reason, people who take B-3 to treat high cholesterol often have their liver enzymes checked when beginning therapy.


Vitamin B-3, or niacin, helps with the body’s organ function, heart health, and DNA repair. Organ meats and fresh fruits and vegetables are good sources of B-3. And it is also available as a supplement.

Excess amounts of B-3 can cause symptoms like inflammation of the liver. So be sure to discuss your intake with your doctor, especially if you also plan to use a supplement.

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