Sun exposure is a known risk factor for non-melanoma skin cancers, particularly squamous cell carcinoma. Researchers believe what happens is that UV initiates DNA damage in skin cells and suppresses cell-mediated immunity, allowing sun damaged cells and cancer cells to escape immune destruction.
Confusingly, the incidence of non-melanoma skin cancer is increasing, despite the increased use of sun screen and increased indoor lifestyles. This has led many to believe that there are more risk factors than UV exposure.
Observational studies have shown that high dietary intake of omega-3s are associated with reduced skin cancer risk. Omega-3s are polyunsaturated fatty acids found mostly in fish. In animal studies, omega-3 intake reduces the suppression of cell-mediated immunity after UV exposure.
Researchers, led by Dr Pilkington of the University of Manchester in the UK, wanted to see if omega 3s would have the same effect on humans in a clinical trial. So they recruited 79 participants and randomized them to take either 5 grams of omega-3s daily or placebo for three months.
After three months of intake, the researchers exposed the enrollees to various doses of UV exposure. What they found is that those in the omega-3 group experienced much less “photo-immunosuppression” than the placebo group. Photo-immunosuppression describes the suppression of cell-mediated immunity on the skin in response to UV.
In the participants that received a UV dose equivalent to 15 minutes of mid-summer sun exposure in the UK, the group that took omega-3s experienced 50% less photo-immunosuppression than those who took placebo.
The authors state,
“This study suggests that supplementation with EPA-rich n-3 PUFA, which is a natural dietary agent, may protect human skin from photo-immunosuppression induced by short exposures to solar UVR. This study adds to the evidence, and indicates a potential mechanism, for protection against skin cancer by n-3 PUFAs in humans.”
What does this mean for you, the person that may like getting vitamin D the natural way? Increasing your intake of omega 3s – either via fish consumption or supplementation – may cut down some of the risk involved in the benefit/risk analysis of getting sun exposure.
Pilkington SM et al. Randomized controlled trial of oral omega-3 PUFA in solar-simulated radiation-induced suppression of human cutaneous immune responses. AJCN, 2013
Here’s a very intriguing article:
Wrong. The abstract states that the results were not statistically significant. Also, the not-statistically significant results only showed a 7% improvement, not a 50% improvement.
Henry, actually, the statement is correct in the context that it was stated. They administered three different doses of UV. In the groups that received the equivalent of 15 minutes of summer sun, the group that received omega 3s experienced 50% less immunosuppression than placebo. I quote the article:
“Immunosuppression was 50% lower after active supplementation compared with after the control at an SSR dose of 3.8 J/cm2, which was equivalent to ∼15 min of summer midday sun in Manchester, United Kingdom (53.5°N).”
That was statistically significant (p=.04). What happened is that they also administered a very high dose of UV, which drowned out the results when pooled together with the lower UV doses.