Definition

Niacin is a type of B vitamin. It is water-soluble, which means it is not stored in the body. Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet.

Alternative Names

Nicotinic acid; Vitamin B3

Function

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

Food Sources

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

Dairy products
Eggs
Enriched breads and cereals
Fish
Lean meats
Legumes
Nuts
Poultry

Niacin and Cardiovascular Disease

For many years, doses of 1 - 3 grams of nicotinic acid per day has been a treatment option for low HDL cholesterol and high LDL cholesterol and triglyceride levels.

Side Effects

A deficiency of niacin causes pellagra. The symptoms include:

Digestive problems
Inflamed skin
Mental impairment

Large doses of niacin can cause:

Increased blood sugar (glucose) level)
Liver damage
Peptic ulcers
Skin rashes

Even normal doses can be associated with skin flushing. New forms of nicotinic acid reduce this side effect. Nicotinamide does not cause these 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 Institute of 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 gender, include:

Recommended Dietary Allowance (RDA): average daily level of intake that is enough to meet the nutrient requirements of nearly all (97 - 98%) healthy people.
Adequate Intake (AI): when there is not enough evidence to develop an RDA, the AI is set at a level that is thought to ensure enough nutrition.

Dietary Reference Intakes for Niacin:

Infants

0 - 6 months: 2* milligrams per day (mg/day)
7 - 12 months: 4* mg/day

*Adequate Intake (AI)

Children

1 - 3 years: 6 mg/day
4 - 8 years: 8 mg/day
9 - 13 years: 12 mg/day

Adolescents and Adults

Males age 14 and older: 16 mg/day
Females age 14 and older: 14 mg/day

Specific recommendations depend on age, gender, and other factors (such as pregnancy). Women who are pregnant or breast-feeding need higher amounts. Ask your health care 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

Escott-Stump S, ed. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.

Sarubin Fragaakis A, Thomson C. The Health Professional's Guide to Popular Dietary Supplements. 3rd ed. Chicago, Il: American Dietetic Association; 2007.

Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, PantothenicAcid, Biotin, and Choline. National Academy Press, Washington, DC, 1998.

Cervantes-Laurean D, McElvaney NG, Moss J. Niacin. In: Shils ME, Olson JA, Shike M, eds. Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md. Williams & Wilkins; 1999:401-411.

AIM-HIGH Investigators. The role of niacin in raising high-density lipoprotein cholesterol to reduce cardiovascular events in patients with atherosclerotic cardiovascular disease and optimally treated low-density lipoprotein cholesterol Rationale and study design. The Atherothrombosis Intervention in Metabolic syndrome with low HDL/high triglycerides: Impact on Global Health outcomes (AIM-HIGH). Am Heart J. 2011 Mar;161(3):471-477.e2.

Reviewed By

Review Date: 08/31/2011

A.D.A.M. Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Alison Evert, MS, RD, CDE, Nutritionist, University of Washington Medical Center Diabetes Care Center, Seattle, Washington (2/14/2011).

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