Vitamin B3 and Skin Cancer: What the '54%' Headline Actually Means
A viral claim says a vitamin B3 supplement cuts skin cancer risk by 54%. That number is real, but it's from people who already had one skin cancer, using nicotinamide specifically, not niacin, and a separate trial in transplant patients found no benefit at all. No trial has tested it in people with no cancer history.
See what the study actually measured A 2025 study of 33,822 US veterans found nicotinamide use linked to 14% fewer new skin cancers overall. The 54% figure applies only to the subgroup who started nicotinamide right after their first skin cancer; the benefit shrank with each additional prior cancer and was driven by squamous cell cancers only, with no reduction in basal cell. Everyone in the cohort already had skin cancer, so this is a recurrence rate, not a general risk cut.
The subgroup context is the single most important thing the viral headline leaves out.
See the trial evidence, including the line nobody quotes In a phase 3 randomized trial of 386 people with at least two prior nonmelanoma skin cancers, nicotinamide 500 mg twice daily cut new nonmelanoma skin cancers 23% over 12 months. The trial's own conclusion, verbatim: 'There was no evidence of benefit after nicotinamide was discontinued.'
This is the strongest positive evidence that exists, and even it comes with a real limit: the benefit did not persist after stopping.
See where the evidence disagrees A randomized trial in organ transplant recipients found 207 new skin cancers on nicotinamide vs 210 on placebo, a rate ratio of 1.0, no difference at all.
Two real randomized trials of the same molecule reached different conclusions in different populations; that disagreement is itself the honest finding.
Check which vitamin B3 you actually mean Nicotinamide is not niacin, and neither is the same as nicotinamide riboside or NMN. Every skin-cancer trial used nicotinamide specifically. Nicotinamide does not cause the flushing niacin does.
Reading a niacin label as if it were the studied molecule is one of the most common mistakes in this story.
See what has never been tested No randomized trial has ever tested nicotinamide for skin cancer prevention in people with no prior skin cancer.
This is the boundary of what the evidence can actually tell someone with no cancer history.
See the intervention with real population-level evidence A randomized trial of 1,621 adults found daily sunscreen cut new squamous cell tumors by about 39% over 4.5 years, in a general population, not just people with prior skin cancer.
This is the strongest single intervention for skin cancer prevention with randomized evidence in ordinary people.
The 54% figure comes from a subgroup of people who already had skin cancer, not a general-population risk cut.
View sources
Niacin Fact Sheet for Health Professionals (NIH Office of Dietary Supplements)
Nicotinamide for Skin Cancer Chemoprevention (Breglio et al., JAMA Dermatology, 2025)
A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention (Chen et al., NEJM, 2015)
Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients (Allen et al., NEJM, 2023)
Daily Sunscreen Use and Squamous Cell Carcinoma (Green et al., Nambour Trial, Lancet, 1999)
Not medical advice. This page is for education only and is not a substitute for professional medical care. Consult a qualified clinician before changing your health routine.
Editorial disclosure. This protocol is written and fact-checked by the YourProtocol editorial team directly from the primary sources cited below; it is not written or reviewed by any outside expert.
Is this for you
- Anyone who saw the '54% lower skin cancer risk' claim and wants the real context
- Anyone with a personal or family history of skin cancer weighing whether to ask a doctor about nicotinamide
- Anyone confused about the difference between niacin, nicotinamide, NR and NMN
Cautions
- This page reports population-level cancer-risk research; it is not a personal risk assessment, and every number here describes a study population, not any individual
- No dosing is given as advice; the ONTRAC trial dose (1,000 mg/day total) is reported only as trial context, far above the 35 mg/day tolerable upper intake level for supplemental niacin
- Anyone with a personal history of skin cancer should route this question to a dermatologist or oncologist, not decide from this page alone
- Educational only, not medical advice