The first clinical trial ever examining the role of omega-3 fish oils on skin immunity, has been published by University of Manchester. In the test, 79 healthy volunteers took a 4g dose of omega-3s from oily fish and then were exposed to 8, 15 or 30 minutes of summer midday in Manchester, or using a light machine. Other patients took a placebo before using the light machine.

Immunosuppression was 50% lower in people who took the omega-3 supplement and were exposed to 8 or 15 minutes of sun. There were no differences in those who faced 30 minutes of sun. The findings have been published in The American Journal of Clinical Nutrition.

"There has been research in this area carried out on mice in the past but this is the first time that there has been a clinical trial directly in people," said Professor Lesley Rhodes. "It has taken a number of years to get to this stage and the findings are very exciting. "This study adds to the evidence that omega-3 is a potential nutrient to protect against skin cancer. Although the changes we found when someone took the oil were small, they suggest that a continuous low level of chemoprevention from taking omega-3 could reduce the risk of skin cancer over an individual's lifetime."

Rhodes stressed that the omega-3 was not a substitute for sunscreen and physical protection, and that omega-3 should be regarded as an additional small measure to help protect skin from sun damage.

Around 100,000 cases of non-melanoma skin cancer were diagnosed in the UK in 2010, making it an extremely common cancer. Skin cancer itself is one of the fastest-growing types of cancer.