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Niacin

Nicotinic acid; Vitamin B3

Niacin is a type of B vitamin. It is a water-soluble vitamin. It is not stored in the body. Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. The body keeps a small reserve of these vitamins, but they have to be taken on a regular basis to maintain the reserve.

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Vitamin B3 benefit
Vitamin B3 deficit
Vitamin B3 source

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Function

Niacin helps the digestive system, skin, and nerves to function. It is also important for changing food to energy.

Food Sources

Niacin (also known as vitamin B3) is found in:

NIACIN AND HEART DISEASE

For many years, doses of 1 to 3 grams of nicotinic acid (another name for niacin) per day have been used as a treatment for high blood cholesterol.

Niacin can help in increasing the level of good cholesterol (HDL cholesterol) in the blood. It can also bring down the amount of unhealthy fat in the blood. Always talk to your health care provider before starting any supplements.

Side Effects

DEFICIENCY:

A deficiency of niacin causes pellagra. The symptoms include:

HIGH INTAKE:

Too much niacin can cause:

When given as a treatment for people with high cholesterol, niacin supplements can cause “flushing.” It is a feeling of warmth, redness, itching or tingling of the face, neck, arms or upper chest.

To prevent flushing, do not drink hot beverages or alcohol with niacin.

New forms of niacin supplements have less side effects. Supplements in the form of nicotinamide or niacinamide do not appear to cause side effects.

Recommendations

REFERENCE INTAKES

Recommendations for niacin and other nutrients are provided in the Dietary Reference Intakes (DRIs), which are developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is the term for a set of reference values that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:

Dietary Reference Intakes for niacin:

Infants (AI)

Children (RDA)

Adolescents and Adults (RDA)

Specific recommendations depend on age, sex, and other factors (such as pregnancy). Women who are pregnant or breastfeeding need higher amounts. Ask your provider which amount is best for you.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods.

References

Markell M, Siddiqi HA. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 27.

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 205. 

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Review Date: 3/11/2021  

Reviewed By: Meagan Bridges, RD, University of Virginia Health System, Charlottesville, VA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 09/29/2021.

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