The Cheap Vitamin That Lowers Skin Cancer Risk
If you have already had a couple of skin cancers cut out, your dermatologist has probably warned you that more are likely on the way. There is now solid evidence that an ordinary B vitamin can shift those odds in your favor, and it costs only a few cents a day.
In a phase 3 randomized controlled trial published in the New England Journal of Medicine, researchers gave high risk patients either 500 milligrams of nicotinamide, a form of vitamin B3, twice a day, or an identical placebo. After one year, the nicotinamide group developed about 23 percent fewer new nonmelanoma skin cancers than the placebo group. You can read the trial here. Because patients were randomly assigned and neither they nor their doctors knew who got the vitamin, the design rules out most of the ordinary explanations, such as the two groups simply having different sun habits.
The mechanism is well understood, which matters when you are weighing whether a result is real. Ultraviolet light drains the energy that skin cells need to repair their own DNA and temporarily weakens local immune defense. Nicotinamide helps replenish that cellular energy, which in turn supports DNA repair after sun exposure. The biology and the trial result tell the same story.
The effect also has limits, and honest reporting means saying so plainly. A later randomized trial tested the same vitamin in organ transplant recipients, whose immune systems are deliberately suppressed, and did not find a significant reduction in skin cancers. The benefit from the original trial appears to hold for high risk people with normal immune function rather than for everyone. Nicotinamide is not a treatment for existing cancer, and it does not replace sunscreen or regular skin checks.
What makes this claim worth taking seriously is not one dramatic number in isolation. It is that a plausible mechanism, a well designed trial, and a sober account of where the effect stops all line up. For someone with a history of nonmelanoma skin cancer, a 23 percent reduction from an inexpensive and widely available vitamin is a reasonable thing to raise at the next dermatology visit.
