Niacin (Nicotinic Acid)

Last reviewed October 19, 2026

In plain words: Niacin (nicotinic acid) is one of the two forms of vitamin B3; the other is nicotinamide. It is added to enrich flour and cereal.

What the evidence review says

Niacin (nicotinic acid) is a form of vitamin B3 added to enriched flour and cereals. At enrichment levels it is a vitamin. Higher doses of this form are linked with skin flushing, and serious liver effects have been described only at drug doses far above food levels.

At the amounts used to enrich a serving of flour or cereal, this is a vitamin, and deficiency causes pellagra. The acid form, unlike nicotinamide, can flush the skin at supplement doses, and European reviewers set an adult upper level for free nicotinic acid on that basis. Serious liver injury has been described only at drug doses taken for months or years, especially with some slow-release products, far above food levels. The upper level does not apply to niacin that is bound inside ordinary foods.

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This page is for general education. It is not medical advice and does not replace advice from your doctor, pediatrician, allergist or registered dietitian. Research changes; we review these pages when new evidence or rules come out. Last reviewed October 19, 2026.