What is the recommended dietary allowance (RDA) for vitamin B-3 (niacin)?

Updated: Jun 01, 2020
  • Author: Mark Rosenbloom, MD, MBA; Chief Editor: Michael A Miller, MD  more...
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Vitamin B-3 (ie, niacin) is found in green vegetables, yeast (pumpernickel bagels may contain 190 mg of niacin), animal proteins, fish, liver, and legumes. Supplements are usually 20-500 mg per tablet.

Vitamin B-3 synthesis requires tryptophan. Niacin is converted to nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP). NAD and NADP are coenzymes for dehydrogenase-type reactions. In large doses, niacin decreases synthesis of LDL cholesterol level. The RDA is 20 mg (9 mg for children aged 1-4 y).

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