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Niacin (B3) on a vegan diet

Niacin comes from brown rice, peanuts and fortified grains directly, and the body has a second route: it converts spare tryptophan from any protein, plant or animal, into niacin on its own.

Vegan Brief Evidence last reviewed August 22, 2026

This is a summary of the cited evidence, not medical advice.

  • Brown rice, 1 cup 5.2 mg niacin (33% of the DV)
  • RDA, adults 14-16 mg NE/day
  • Backup route Body converts tryptophan into niacin

The short version

Niacin, or vitamin B3, becomes the coenzyme NAD inside every tissue in the body, and NAD is the workhorse behind more enzyme reactions than any other vitamin-derived coenzyme.

Primary source 01 / 03

All tissues in the body convert absorbed niacin into its main metabolically active form, the coenzyme nicotinamide adenine dinucleotide (NAD).

NIH Office of Dietary Supplements Niacin (fact sheet for health professionals), 2022

Adults need 14 to 16 mg a day, counted in niacin equivalents. That unit matters here, because niacin has a second source most people never think about.

Direct sources, plus a built-in backup

Brown rice supplies a third of the Daily Value in a cup, peanuts a quarter in an ounce, and fortified cereal a quarter in a single serving. Lentils, sunflower seeds and whole wheat bread add smaller amounts on top.

Primary source 02 / 03

Plant-based foods, such as nuts, legumes, and grains, provide about 2–5 mg niacin per serving, mainly as nicotinic acid.

NIH Office of Dietary Supplements Niacin (fact sheet for health professionals), 2022

On top of that, any protein with enough tryptophan, plant or animal, gives the body raw material to build its own niacin. That conversion is exactly why the RDA is written in niacin equivalents rather than plain milligrams.

Who actually falls short

The deficiency disease, pellagra, causes a sunburn-like rash and, if untreated, serious neurological decline. It is genuinely rare today.

Primary source 03 / 03

Severe niacin deficiency leads to pellagra, a disease characterized by a pigmented rash or brown discoloration on skin exposed to sunlight.

NIH Office of Dietary Supplements Niacin (fact sheet for health professionals), 2022

NIH ties pellagra today to poverty-level undernutrition and to conditions such as alcohol use disorder and inflammatory bowel disease, not to a plant-based diet as such. A varied plate with legumes and whole grains covers both the direct and the backup route.

  • Thiamine (B1) on a vegan diet Thiamine hides in whole grains, legumes and fortified cereal at levels that meet the RDA with room to spare, and the deficiency risk list runs through alcohol use disorder and bariatric surgery, not what's on the plate.
  • Vitamin B6 on a vegan diet Vitamin B6 turns up in chickpeas, potatoes and bananas in amounts that rival or beat meat, and the federal government's own list of at-risk groups never once mentions diet type.
  • Riboflavin (B2) on a vegan diet Riboflavin is a quiet one: no dramatic deficiency story, just the fact that dairy and eggs carry a lot of it. Take those away and the NIH puts vegans on the watch list, which fortified foods and a few staples handle.

Frequently asked

Do vegans get enough niacin without meat?

Yes. Brown rice, peanuts, lentils and fortified cereal all provide niacin directly, and the body separately converts tryptophan from any dietary protein into niacin as a backup source.

What is pellagra and is it a vegan risk?

Pellagra is severe niacin deficiency, causing a sunburn-like rash and eventually neurological symptoms. It is now largely confined to famine and extreme poverty, and NIH does not list vegans as an at-risk group.

The primary sources

The documents this page quotes. Read them yourself.

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