Niacin (Vitamin B3)

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    Katie Jantz

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    Thomas Solomon
    Last Updated: December 4, 2025

    Niacin is a form of vitamin B3. Supplementation with niacin (nicotinic acid) can improve cholesterol levels; however, niacin's inability to reduce cardiovascular disease risk and its association with adverse effects make its use controversial.

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    Overview

    Dosage Information

    Formulation

    Niacin (nicotinic acid) supplements are available in a variety of oral preparations, including tablets and capsules.

    To reduce the risk of flushing (a sudden reddening, warming, and/or tingling of the skin), some niacin supplements are formulated as controlled release, meaning that the niacin gets released slowly over time, rather than all at once. However, supplements marketed as “no-flush” niacin often contain nicotinamide or inositol hexanicotinate, rather than nicotinic acid. Although these alternate forms are effective for correcting a vitamin B3 deficiency, they do not appear to provide the same cholesterol-lowering effect.[1][2]

    Niacin is also available as a high-dose prescription medication in some countries, either as an immediate-release or extended-release product.

    Range of dosages studied

    Niacin has been studied at dosages ranging from 15 mg to 6,000 mg (6 grams) taken daily for up to 6 years. For reducing cholesterol levels, dosages of at least 500 mg daily are commonly used.[2][3]

    Higher doses of niacin (1,500 mg daily and more) are associated with potentially serious adverse effects, including worsening of glycemic control[4][5] and liver toxicity[6].

    Other considerations

    The niacin Recommended Dietary Allowance (RDA) is the minimum amount of niacin that should be consumed daily to prevent deficiency. This amount can include any form of vitamin B3, including nicotinic acid, nicotinamide, or nicotinamide riboside. The niacin RDA is given in niacin equivalents to allow for the inclusion of dietary tryptophan, which can be converted into niacin.[7]

    Niacin RDA

    AGEMALEFEMALEPREGNANTLACTATING
    0–6 months2 mg*2 mg*——
    7–12 months4 mg NE4 mg NE——
    1–3 years6 mg NE6 mg NE——
    4–8 years8 mg NE8 mg NE——
    9–13 years12 mg NE12 mg NE——
    14–18 years16 mg NE14 mg NE18 mg NE17 mg NE
    19+ years16 mg NE14 mg NE18 mg NE17 mg NE

    NE, niacin equivalent: 1 mg NE = 1 mg niacin = 60 mg tryptophan
    * Adequate intake (AI)
    Reference: Institute of Medicine. Niacin (chapter 6 of Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. The National Academies Press. 1998. DOI: 10.17226/6015)

    The tolerable upper intake level (UL) of niacin outlines the maximum doses that are unlikely to cause the side effect of flushing. Taking niacin with food can also help reduce the risk of flushing.[7]

    Niacin UL

    AGEMALEFEMALEPREGNANTLACTATING
    0–12 monthsNot established*Not established*——
    1–3 years10 mg10 mg——
    4–8 years15 mg15 mg——
    9–13 years20 mg20 mg——
    14–18 years30 mg30 mg30 mg30 mg
    19+ years35 mg35 mg35 mg35 mg

    * Source of intake should be from breast milk, formula, and food only.
    Reference: Institute of Medicine. Niacin (chapter 6 of Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. The National Academies Press. 1998. DOI: 10.17226/6015)

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