Vitamin B3: Niacin vs. Niacinamide vs. NR — What's the Difference?

Vitamin B3 exists in multiple forms, and the differences between them are far more significant than most people realize. Niacin (nicotinic acid), niacinamide (nicotinamide), and the newer nicotinamide riboside (NR) all contribute to NAD+ production, but they have very different effects in the body beyond that shared endpoint.

NAD+ — The Common Thread

All forms of vitamin B3 serve as precursors to nicotinamide adenine dinucleotide (NAD+), one of the most important molecules in cellular metabolism. NAD+ is required for over 400 enzymatic reactions, including energy production in the mitochondria, DNA repair, and the activity of sirtuins (proteins linked to aging and cellular maintenance). For a deeper dive into NAD+ and aging research, see NAD+ Precursors.

Niacin (Nicotinic Acid)

Niacin is the form that causes the famous "niacin flush" — a temporary reddening and warming of the skin caused by prostaglandin-mediated vasodilation. At pharmacological doses (1,000-2,000 mg), niacin raises HDL cholesterol and lowers triglycerides, though its clinical use for cardiovascular outcomes has become controversial after the AIM-HIGH and HPS2-THRIVE trials.

Niacinamide (Nicotinamide)

Niacinamide doesn't cause flushing and doesn't have the same lipid-modifying effects. It's the form most commonly used in multivitamins and skincare products (where it's used topically for skin barrier support). Niacinamide is efficiently converted to NAD+ but at very high doses may actually inhibit sirtuins.

Nicotinamide Riboside (NR) & NMN

NR and nicotinamide mononucleotide (NMN) are newer supplemental forms that have gained attention for their potential to boost NAD+ levels more efficiently. They're the primary focus of longevity research around NAD+ restoration. See the dedicated NAD+ Precursors page for details on NR vs. NMN.

Food Sources

Dietary niacin is found in poultry, tuna, beef, peanuts, mushrooms, and enriched grains. The amino acid tryptophan can also be converted to niacin at a ratio of approximately 60:1, meaning protein-rich diets contribute indirectly to niacin status.

Historical note: Pellagra, the disease of severe niacin deficiency, was epidemic in the early 20th century American South where diets relied heavily on corn (which contains niacin in a bound, unavailable form). Nixtamalization — the traditional alkaline treatment used in Mexican cuisine — releases bound niacin, which is why pellagra was common in the US but not in Mexico.

See The Complete B-Complex for how niacin interacts with other B vitamins.

External resources: Linus Pauling Institute — Niacin