While many people love getting some sun, they know how damaging catching too many rays can be for the skin. Ultraviolet (UV) radiation exposure can directly impair DNA, increase the production of damaging molecules to cells called reactive oxygen species, activate local inflammation, and deplete cellular energy, all leading to cell death. People consume nicotinamide, a form of vitamin B3, by daily diet and is the precursor of nicotinamide adenine dinucleotide (NAD+), a key coenzyme for different vital processes, such as cell energy production, maintenance of cellular health, and DNA damage repair. However, not much is known about whether nicotinamide can have reparative or preventative effects on human skin cells exposed to UV radiation. 

Researchers from Novara, Italy, presented research at the 29th European Academy of Dermatology and Venereology (EADV) Congress, EADV Virtual, showing hope that nicotinamide could protect skin cells from the effects of UV exposure. This study elucidated the role of nicotinamide in protection against UV-induced stress in human skin cells. Lara Camillo, a research student from the Dermatological Unit of AOU Maggiore della Carità, Novara, Italy said in a press release, “Our study indicates that increasing the consumption of vitamin B3, which is readily available in the daily diet, will protect the skin from some of the effects of UV exposure, potentially reducing the incidence of non-melanoma skin cancers. However, the protective effect of vitamin B3 is short-acting, so it should be consumed no later than 24 to 48 hours before sun exposure.”

There are two main types of skin cancer: non-melanoma skin cancer (which includes basal cell skin cancer, squamous cell skin cancer, and other rare types) and melanoma skin cancer. Basal and squamous cell cancers are most often found in areas exposed to the sun, such as the head, neck, and arms, but they also can occur elsewhere. Non-melanoma skin cancer is the 5th most commonly occurring cancer in men and women, with over 1 million diagnoses worldwide in 2018. Although non-melanoma skin cancer is usually treatable, there is a need for preventative measures for this affliction since it is so common that it is the most common source of malignancy in the Caucasian population with the incidence rate increasing worldwide.

Most skin cancer is caused by UV light damaging the DNA in skin cells. The main source of UV light is sunlight. Sunlight contains 3 types of UV light, ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC). The earth’s atmosphere filters out only UVC. Both UVA and UVB damage skin over time, making it more likely for skin cancers to develop. UVB is considered to be the main cause of non-melanoma skin cancer. Artificial sources of UV light, such as sunlamps and tanning beds, also increase your risk of developing skin cancer. Repeated sunburn, either by the sun or artificial sources of light, will make your skin more vulnerable to non-melanoma skin cancer.

Camillo and colleagues wanted to see if nicotinamide can protect the skin from some of the effects of UV exposure, potentially reducing the incidence of non-melanoma skin cancers. So, the investigators tested the effects of nicotinamide on isolated human skin cells from the skin surrounding a cancerous lesion in patients with non-melanoma skin cancer, aged 50-80 years, surgically treated at Dermatological Unit of AOU Maggiore della Carità, Novara, Italy. Then, researchers treated the cells with different concentrations of nicotinamide for 18, 24, and 48 hours before UVB exposure. They then looked at whether nicotinamide promoted cell survival and the ability of cells to tolerate different kinds of stress and inflammation produced by UVB exposure.

The investigators found that the ability of these skin cells to survive was not affected by either nicotinamide or UVB treatment in all conditions. The levels of DNA repair enzymes were significantly enhanced by UVB exposure, indicating an increase in DNA damage. Pretreating these cells with nicotinamide protected them from DNA damage, decreasing levels of DNA repair enzymes.

After UVB exposure, nicotinamide pretreatment at all concentrations decreased markers of oxidative stress as seen by a reduction in the production of reactive oxygen species, which can, in high levels, cause damage to DNA and cells. Pretreating cells with nicotinamide also reduced the levels of a molecule that plays a pivotal role in inflammation in human skin called nitric oxide that is increased by UVB exposure, which was accompanied by a decrease in levels of an enzyme that generates nitric oxide. Similarly, UVB exposure also weakly increased levels of pro-inflammatory molecules, and nicotinamide pretreatment seemed to block this local inflammation.

Their results demonstrated that nicotinamide pretreatment protects human skin cells from UVB impairment effects by enhancing DNA repair, decreasing reactive oxygen species production, decreasing nitric oxide release, and blocking local inflammation. The most drastic effects of pre-treating cells with nicotinamide was seen 1 day before exposure to UVB.

This study shows that what you eat can actually help your skin better defend against the sun’s rays. Camillo and colleagues show that vitamin B3 can protect the skin from UVB exposure, likely bringing down the risk of developing skin cancer.