Eating oily fish twice a week could protect against skin cancer, according to new research.

Omega-3 fatty acids found in oily fish, such as sardines, mackerel and trout, destroy malignant cells in skin and mouth tumours.

The discovery may lead to aerosols or gels containing the molecules that kill skin and mouth cancers.

Adults are advised to eat fish at least twice a week, including one portion of oily fish. A portion is 140g or six ounces Experiments found the omega-3 fatty acids stopped induced cell death in both early and late stages of the diseases. As well as oily fish, flaxseeds and walnuts are also a good source of the molecule that have been shown to ward off heart disease.

Professor Kenneth Parkinson, of Queen Mary, University of London, said: “We found the omega-3 fatty acid selectively inhibited the growth of the malignant and pre malignant cells at doses which did not affect the normal cells.

“Surprisingly, we discovered this was partly due to an over stimulation of a key growth factor (epidermal growth factor) which triggered cell death. This is a novel mechanism of action of these fatty acids.”

Previous research has already linked omega-3 fatty acids with the prevention of a number of cancers. In the new research, the experts looked at a particular type of cancer called SCC (squamous cell carcinoma), one of the major forms of the disease. Squamous cells are the main part of the outermost layers of the skin, and also occur in the lining of the digestive tract, lungs and other areas of the body.

Oral squamous cell carcinomas (OSCC) are the sixth most common cancer worldwide and are difficult and very expensive to treat. The scientists grew cultures from several different cells lines, including both malignant oral and skin SCCs along with pre malignant cells and normal skin and oral cells, to which they added the fatty acids.

Lab member Dr Zacharoula Nikolakopoulou said: ‘As the doses needed to kill the cancer cells do not affect normal cells, especially with one particular fatty acid we used called EPA (Eicosapentaenoic acid), there is potential for using omega-3 fatty acids in the prevention and treatment of skin and oral cancers. “It may be those at an increased risk of such cancers, or their recurrence, could benefit from increased omega-3 fatty acids. Moreover, as the skin and oral cancers are often easily accessible, there is the potential to deliver targeted doses locally via aerosols or gels. However further research is needed to define the appropriate therapeutic doses.”