In 2015 Niacinamide Cut New Skin Cancers by 23 Percent. In 2023 It Walked Into a Tougher Room.

The Oasis Health Journal · Submitted July 24, 2026 · 2:17 PM ET

Vitamin B3 has three names and a bit of an identity problem. Niacin, nicotinamide, niacinamide. The generic word niacin covers nicotinic acid, nicotinamide (which is the same thing as niacinamide), and a few cousins, and your body converts all of them into NAD, the coenzyme that more than 400 of your enzymes cannot clock in without. That sounds like trivia until you notice that two of these forms behave like completely different drugs, and one of them walked into a skin cancer trial in 2015 and walked out with a headline.

Start with the naming, because the supplement shelf is going to try to trip you. Nicotinic acid is the form that makes you flush. You take it, and about twenty minutes later your face and neck go red, warm, and prickly, like you got caught doing something. That is the version cardiologists once used in large doses to move cholesterol around. Niacinamide is the same vitamin with an amide group swapped in for the acid group, and that one small edit changes the whole personality. It does not flush you, and it does not touch your cholesterol. When a dermatologist says B3, this quiet one is the form they mean.

In 2015 the New England Journal of Medicine published a trial called ONTRAC. Researchers in Australia recruited 386 people who were, to put it politely, skin cancer regulars. Everyone enrolled had already had at least two non-melanoma skin cancers in the previous five years. Half took niacinamide, 500 mg twice a day. Half took an identical-looking placebo. Twelve months later the niacinamide group had 23 percent fewer new non-melanoma skin cancers. Squamous cell carcinomas fell about 30 percent. Actinic keratoses, the rough sun spots that are basically skin cancers filling out the early paperwork, dropped too. The pills were cheap, over the counter, and unglamorous, which is exactly what you want in a preventive.

The proposed reason is not mystical. Ultraviolet light does two rude things to skin. It damages the DNA inside your skin cells, and it briefly dims the local immune system that would otherwise spot the damage and deal with it. Niacinamide tops up the NAD that skin cells burn to repair DNA and keep their internal power running, and it appears to soften that UV immune dip. Give the repair crew more fuel and steadier lights, and fewer errors graduate into tumors. That was the theory, and for one year, in that particular group of people, it held.

Here is where the story grows up. The people who get skin cancer most, by a wide margin, are organ transplant recipients. The anti-rejection drugs that keep a new kidney or heart from being attacked also keep the immune system from patrolling sun-damaged skin, so cancers pile up fast. The obvious next question was whether niacinamide, the DNA-repair helper, could protect the people who need protecting most. A second trial, ONTRANS, ran the same 500 mg twice a day for a year and reported in the same journal in 2023.

It did nothing. At twelve months there were 207 new keratinocyte cancers in the niacinamide group and 210 in the placebo group. That is not a narrow miss. That is a coin landing on its edge. The actinic keratosis counts came out even too. Same vitamin, same dose, same journal, opposite result. The difference was the room. In immune-competent sun veterans, niacinamide helped. In heavily immunosuppressed transplant patients, the immune step it was supposed to nudge was already pinned to the floor by medication, and a vitamin was never going to lift it back up.

So what do you do with a supplement that won one trial and shrugged through the next? You read the fine print, which is the entire job of this journal. Niacinamide is not sunscreen, not a treatment, and not a reason to skip the dermatologist. The ONTRAC benefit also faded once people stopped taking the pills, so it was a maintenance effect rather than a cure. But for a normal, immune-competent person with a sunburned history and a growing folder of biopsies, a cheap, well-tolerated B vitamin with one solid positive trial behind it is a fair thing to raise with a doctor.

If you go looking, the form matters more than the marketing on the front of the box. A plain niacinamide or vitamin B3 supplement is the one actually studied here, and a B complex will usually spell out which form it uses on the label. Skip anything labeled NMN, which is a different molecule borrowing the family name. We make our professional-grade formulas fresh per order instead of letting them age on a warehouse shelf, so shipping runs a little slower and the potency lands a little higher, which for a repair-fuel vitamin is the trade you want. Rounding out the basics your skin already runs on, like vitamin C, is reasonable, but the trials tested B3 by itself, so keep your expectations aimed at what was measured.

This article is for education only and is not medical advice. Supplements are not drugs and do not prevent, treat, or cure cancer, and niacinamide is no substitute for sun protection or a dermatologist. Talk with a qualified clinician before starting anything new, especially if you are immunosuppressed or take other medications.

Sources

1. Chen AC et al. A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention (ONTRAC), NEJM 2015
2. Allen NC et al. Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients (ONTRANS), NEJM 2023
3. The ASCO Post. Nicotinamide for Chemoprevention of Skin Cancer in Solid Organ Transplant Recipients, 2023
4. NIH Office of Dietary Supplements. Niacin Fact Sheet for Health Professionals
5. Chen AC et al. ONTRAC trial, PubMed 26488693