AUCKLAND, NEW ZEALAND. Medical researchers in New Zealand provide convincing evidence that an increased consumption of fish oils helps reduce the risk of developing prostate cancer. Their study involved 317 men who had been diagnosed with prostate cancer during 1996-97 and 480 age-matched controls. Blood samples were obtained from all participants and the erythrocyte (red blood cell) phosphatidylcholine fraction of the plasma was analyzed for EPA and DHA (eicosapentaenoic acid and docosahexaenoic acid, respectfully), the two main components of fish oils.
Evaluation of the collected data showed a clear correlation between blood level of EPA and DHA and the presence of prostate cancer. Study participants with levels in the highest quartile were found to have a 40 per cent lower incidence than participants with levels in the lowest quartile. This relationship held true even when adjusted for age, height, use of NSAIDs (non-steroidal anti-inflammatory drugs), socio- economic status, and estimated intake of lycopene and polyunsaturated fats.
The researchers also found that men with low socio-economic status, a low intake of lycopene, and non- regular use of NSAIDs were more likely to develop prostate cancer. They did not, however, find any correlation between self-reported intake of EPA and DHA indicating that food frequency questionnaires are not an accurate method for estimating fish oil intake. The researchers speculate that fish oils may prevent the progression of prostate cancer by inhibiting the biosynthesis of eicosanoids from arachidonic acid.
Norrish, A.E., et al. Prostate cancer risk and consumption of fish oils: a dietary biomarker-based case-control study. British Journal of Cancer, Vol. 81, No. 7, December 1999, pp. 1238-42