Omega-3 fatty acids appear to slow prostate cancer

Research in mice suggests that a diet high in omega-3 fatty acids found in fish oil and certain types of fish could potentially improve the prognosis of men who are genetically prone to develop prostate cancer.

“This study clearly shows that diet can tip the balance toward a good or a bad outcome,” said Senior Researcher Yong Q Chen, from Wake Forest University School of Medicine. “It’s possible that a change in diet could mean the difference between dying from the disease and surviving with it.”

In mice that were engineered with a genetic defect causing prostate cancer, a diet high in omega-3 fatty acids beginning at birth reduced tumour growth, slowed disease progression and increased survival. The research is reported online today by the Journal of Clinical Investigation and will appear in the 2 July print issue.

Prostate cancer is the most frequently diagnosed cancer and is a leading cause of death in men in the USA. Population studies have suggested that consumption of fish or fish oil reduces prostate cancer incidence. However, these investigations have been hampered by the difficulty people have in accurately reporting their dietary intake.

The goal of the current study was to explore gene-diet interactions in prostate cancer. It involved mice that were engineered with a genetic defect – they lacked a tumour suppressor gene and spontaneously developed prostate cancer. This gene (Pten) is absent in 60-70% of metastatic cancers in humans.

The engineered mice and “wild-type” (or non-engineered) mice were fed varying levels of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs). Both are “essential” fatty acids, which means the body needs them for proper cell function but cannot produce them. Many vegetable oils contain omega-6 PUFA. Fish like mackerel, lake trout, herring, sardines, albacore tuna and salmon are high in omega-3 fatty acids. Nutritionists recommend that people consume equal proportions of omega-3 and omega-6 PUFA. However, in current western diets, the proportion of omega-6 to omega-3 is between 30 and 50 to one.