Vitamin B3 — Niacin

Niacin is a B vitamin the body uses across hundreds of metabolic reactions — most importantly converting food into energy, but also supporting DNA repair and cellular function. It’s one of the more broadly active B vitamins in terms of how many processes it touches, even if it rarely gets talked about.

One thing that makes niacin somewhat unique among the B vitamins is that the body can produce some of it on its own from tryptophan, an amino acid found in protein-rich foods like chicken, turkey, and eggs. That’s part of why outright deficiency is uncommon in people eating adequate protein — the body has a backup route. Severe deficiency, called pellagra, was historically significant in populations with very limited dietary variety, but it’s rarely seen today.

Meat, poultry, and fish are the richest sources. Whole grains, legumes, and peanuts also contribute meaningfully. For most people eating a varied diet with regular protein, niacin status takes care of itself.

Reference Card

Vitamin type: Water-soluble Pillar: Nourish

What it does for you

Converts food into usable energy
Supports DNA repair and cellular function

Where to get it

Chicken, turkey, beef, tuna, salmon, peanuts, whole grains, legumes, fortified cereals

Considerations

Water-soluble — needs regular replenishment through food
The body can produce some niacin from tryptophan — adequate protein intake supports niacin status
Deficiency is uncommon in people eating adequate protein and dietary variety

Signs your intake might be low

Fatigue and low energy
Digestive issues
Skin that’s unusually sensitive to sun exposure

Common myths

You need to worry about niacin separately from protein — if you’re eating enough protein from varied sources, niacin status generally follows