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Vitamin B-3, also known as niacin, is one of eight B vitamins. It plays a role in converting the food we eat into energy. It helps the body to use proteins and fats, and it keeps the skin, hair, and nervous system healthy.

Other possible benefits of vitamin B-3 stem from its potential cholesterol-lowering, antioxidative, and anti-inflammatory properties.

Other names for vitamin B-3 include nicotinamide, nicotinic acid, and vitamin PP, because it prevents pellagra.

The body excretes any niacin it does not need in urine. The body does not store niacin, and so people must consume it in food every day.

A healthful diet can provide all of a person's vitamin B-3 needs. Vitamin B-3 deficiency is rare in the United States.

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Food sources of niacin, such as cooked brown rice, can help prevent a deficiency.

In the past, niacin deficiency was common, especially in the Southern States of the U.S. Now, however, most people get enough vitamin B-3 in their diet.

According to the Office of Dietary Supplements (ODS), a person who lacks vitamin B-3 may experience:

  • a pigmented rash on skin that is exposed to the sun
  • rough appearance to the skin
  • bright red tongue
  • fatigue or apathy
  • vomiting, constipation, and diarrhea
  • circulatory problems
  • depression
  • headache
  • memory loss
  • in severe cases, hallucinations

A severe lack of vitamin B-3 can result in pellagra. The condition can be fatal.

Factors that can lead to low levels of B-3 include:

  • having a diet low in tryptophans or a condition that reduces the body's ability to convert tryptophan to niacin, such as Hartnup disease or carcinoid syndrome
  • undernutrition, for example, due to alcohol use disorder, anorexia, and inflammatory bowel disease
  • a low intake of vitamin B-2, B-6, or iron, as this can reduce the amount of tryptophan that converts to niacin

Click here to find out more about vitamin B-3 deficiency.

In the past, some people have combined vitamin B-3 with statin use as a treatment to control cholesterol. However, research into this has produced mixed results, and some people have had adverse effects.

For this reason, the American College of Cardiology and the American Heart Association do not recommend using this treatment.

Risks

The amount of vitamin B-3 found in food does not cause side effects. However, taking high doses of vitamin B-3 as a supplement can result in adverse effects.

These include:

  • flushed or itchy skin
  • nausea
  • vomiting
  • constipation
  • headache
  • rash
  • dizziness

Excess vitamin B-3 can also:

  • reduce glucose tolerance and insulin resistance
  • trigger an attack in people with gout
  • result in eye problems
  • lead to gastrointestinal problems
  • increase the risk of liver damage
  • lower blood pressure, leading to a loss of balance and risk of falls

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If a doctor recommends niacin supplements, be sure to use the correct dosage.

The National Institutes of Health (NIH) Dietary Supplement Label Database recommend 16 milligrams (mg) a day of vitamin B-3 for anyone of 4 years of age or over who is consuming a 2,000-calorie diet.

On this basis, those who eat a well-balanced diet will tend to consume enough niacin in their food.

Vitamin B supplements are available to purchase online, but people should check first with a doctor to make sure they are safe to take.

The following foods are good sources of vitamin B-3:

  • Beef liver: A 3-ounce portion contains 14.9 mg or 75 percent of a person's daily value (DV)
  • Grilled chicken breast: A 3-ounce portion contains 10.3 mg or 52 percent of DV
  • Turkey breast: A 3-ounce portion has 10.0 mg or 50 percent of DV
  • Sockeye salmon: A 3-ounce piece contains 8.6 mg or 43 percent of DV
  • Cooked brown rice: One cup provides 5.2 mg or 26 percent of DV
  • Enriched breakfast cereal: One serving contains 5.0 mg or 25 percent of DV
  • Dry roasted peanuts: One ounce of these nuts contains 4.2 mg or 21 percent of DV

Foods that are high in tryptophan are good sources of niacin. The body needs tryptophan to make protein, but if there is extra, it can convert it to niacin.

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Pellagra symptoms include changes in skin color.
Image credit: Herbert L. Fred, MD, Hendrik A. van Dijk, 2010

In countries where corn and rice are the main sources of nutrition, pellagra is still a public health problem. Corn and rice have low levels of vitamin B.

In 1914, the U.S. Public Health Service asked Dr. Joseph Goldberger to go to the South of the country to investigate and deal with pellagra. Rates of pellagra were much higher in the southern states than in the north.

Dr. Goldberger inspected prisons, psychiatric hospitals, and orphanages. He found that pellagra rates among the children, prisoners, and patients were considerably higher than rates among the staff, and he concluded that pellagra was not an infection, but that it was probably related to diet.

When staff added brewer's yeast to the diets of those people they were in charge of, all the signs and symptoms of pellagra disappeared.

In 1937, scientists confirmed the niacin connection. Niacin can both prevent and cure pellagra.

Now, pellagra is rare in the U.S. because the diet of most people provides sufficient vitamin B-3, partly due to the enrichment of foods with the vitamin.

The Centers for Disease Control and Prevention's (CDC) list the discovery of niacin's link with pellagra and the nutritional improvements that have led to its decrease in its list of top 10 public health achievements from 1900 to 1999.