Nicotinamide occurs in trace amounts mainly in meat, fish, nuts, and mushrooms, as well as to a lesser extent in some vegetables.
Some countries demands fortification with nicotinamide of some foods. For example, the UK requires the vitamin for fortification of flour and bread.
All 386 participants in the University of Sydney study had a history of skin cancer, increasing their risk for additional skin cancers. Taken as a twice-daily pill for 12 months, nicotinamide reduced the incidence of new non-melanoma skin cancers by 23% relative to placebo controls, and cut the incidence of pre-cancerous sun spots by around 15%.
Nicotinamide is safe, affordable, and available over the counter in most countries. The findings have the potential to decrease the health burden and economic cost of skin cancer—the most common form of cancer in fair-skinned populations worldwide.
“This is the first clear evidence that we can reduce skin cancers using a simple vitamin, together with sensible sun protection,” said the study’s senior author, Dr Diona Damian, a professor of dermatology at the Sydney University and the Royal Prince Alfred Hospital.
“We hope that these findings can be immediately translated into clinical practice. However, people at high risk of skin cancer still need to practice sun safe behaviour, use sunscreens and have regular check-ups with their doctor.”
The primary cause of non-melanoma skin cancer is sun exposure. Despite intensive sun protection campaigns, the incidence of skin cancer continues to increase worldwide. In Australia, non-melanoma skin cancers affect more than half of the population. It is four times as common as all other cancers combined, and costs the nation more than A$500m (US$362m) annually.
The most common types of non-melanoma skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). SCCs can metastasise or spread to lymph nodes and internal organs. BCCs rarely spread but can cause huge cosmetic problems as they often occur on the face. Nicotinamide had comparable efficacy in preventing BCCs and SCCs.
In the study, 386 patients with an average age of 66 years who had at least two non-melanoma skin cancers in the last five years—and were therefore considered to be at high risk—were randomly assigned to daily nicotinamide or placebo for 12 months. The study population reflected the mix of patients typically seen in a skin cancer clinic.
The rate of new non-melanoma skin cancer was 23% lower in the nicotinamide group compared to the placebo group. The average number of actinic keratoses—pre-cancerous sun spots—in the nicotinamide group was consistently lower during treatment, ranging from an 11% reduction at three months, to a 20% at nine months.
The study was not designed to test whether nicotinamide would benefit people in the general population who have not had skin cancer, or whether it could be effective in reducing melanoma.
While the researchers hope to investigate these questions in the future, there is currently no evidence that nicotinamide should be used in these settings.
This study builds on a decade of evidence from preclinical and early clinical studies which suggests nicotinamide enhances the repair of DNA in skin cells damaged by sunlight. The vitamin also appears to protect the skin’s immune system from UV radiation by providing skin cells an extra energy boost when they are in repair-mode after sun exposure.
Nicotinamide, which is a different form of vitamin B3 to nicotinic acid or niacin, was very well tolerated, with no difference in adverse events, blood results or blood pressure.
Nicotinic acid commonly causes headaches, flushing and low blood pressure, but these side effects are not seen with nicotinamide.