Niacin (B3) upper limit: how much is too much per day?

For adults 19 and older, the upper limit (UL) of niacin (B3) is 35 mg per day, counting niacin from supplements and fortified foods only.

Ages 14 and older · Source: National Academies Dietary Reference Intakes · Data as of 2026-10-03

Every life stage

Group	Age	RDA or AI mg NE/day	UL mg/day
Male	14–18	16 RDA	30
Male	19–30	16 RDA	35
Male	31–50	16 RDA	35
Male	51–70	16 RDA	35
Male	71+	16 RDA	35
Female	14–18	14 RDA	30
Female	19–30	14 RDA	35
Female	31–50	14 RDA	35
Female	51–70	14 RDA	35
Female	71+	14 RDA	35
Pregnancy	14–18	18 RDA	30
Pregnancy	19–30	18 RDA	35
Pregnancy	31–50	18 RDA	35
Lactation	14–18	17 RDA	30
Lactation	19–30	17 RDA	35
Lactation	31–50	17 RDA	35

RDA = Recommended Dietary Allowance; AI = Adequate Intake, used where there is not enough data for an RDA. UL = Tolerable Upper Intake Level. “Not set” means the tables give no value. Ages under 14 are in the National Academies tables and are not covered here.

What counts toward the limit

This UL covers niacin (B3) from supplements and fortified foods only. Niacin that occurs naturally in food does not count.

The RDA is in mg NE (niacin equivalents); the UL is in mg of niacin.

Table footnote, as recorded in Ceiling’s data: “UL applies to niacin from supplements and fortified foods only, not to niacin naturally in food.”

How Ceiling uses this

Ceiling adds up every supplement you scan and compares your daily total with this number, counting only the forms the UL covers. Ceiling is coming soon on iPhone. No account; everything stays on your iPhone.

What is the upper limit of niacin (B3)?