This study reviewed and analyzed all scientific literature published through 2009 about fish consumption and prostate cancer. The researchers aimed to find if fish consumption lowers the risk of prostate cancer and its development. It was found that the overall chances of a person developing prostate cancer (incidence of disease) were not influenced by dietary fish consumption. But in people who consumed fish, the metastasis of prostate cancer to other areas of the body was significantly lowered. Death due to prostate cancer was also significantly lowered in this group.
There is a large difference in incidence of and death related to prostate cancer reported from different populations across the world. This suggests that lifestyle factors like diet may influence the disease. For example, Alaskan Eskimos and Japanese people who traditionally consume a high amount of fish, have very low incidence of prostate cancer. Laboratory research has also indicated that omega-3 polyunsaturated fatty acids limit the growth and spread of prostate cancer in animal models. Fish is rich in the long-chain marine omega-3 polyunsaturated fatty acids.
However, studies published so far have looked at different parameters regarding fish consumption, used different methods of analysis and arrived at different conclusions. This comprehensive review analyzing all such reports is important because it gives a holistic picture rather than views based on results of individual research papers.
• Researchers searched through electronic databases like MEDLINE, EMBASE etc. for all research papers about prostate cancer and dietary fish and reviewed the results.
• The findings were based on data obtained from 24 studies of two types: case-control and cohort studies. 12 case-control studies compared 5,777 cases of prostate cancer patients to 9,805 control subjects. Another 12 cohort studies included a total of 445,820 men who 13,924 suffered from prostate cancer.
• Statistical analysis was performed to find the link between fish consumption and occurrence as well as development of prostate cancer.
• The statistical meta-analysis in this report indicated that the overall chances of a person developing prostate cancer (incidence of disease) were not influenced by dietary fish consumption.
• However, in people who included fish in their diets, the spread of prostate cancer to other areas of body (metastasis) was lowered by 44 percent.
• Also in people regularly eating fish, death specifically attributed to prostate cancer was significantly lowered by 63 percent as compared to people not consuming fish.
The findings looked at total fish consumption. It did not analyze the effect of different varieties of fish, e.g., fatty fish like salmon and tuna, or those lower in marine fatty acids like cod and flounder. The study looked at pooled data that included different fish preparation methods, e.g., deep-frying that might add unhealthy fat to diet and thereby be associated with prostate cancer. Also, there was very little information available on cases of high-grade and locally advanced prostate cancer. More studies are needed on the aggressive and lethal form of the disease.
A patient suffering from prostate cancer is likely to have less chances of cancer spreading to other parts of body and is expected to live longer if his regular diet contains fish. Fish is rich in polyunsaturated fatty acids. These fatty acids play an important role in inflammatory response, new cell proliferation and growth of new blood vessels. All three mechanisms are closely related to development and spread of cancer. It seems that a diet rich in fish may be protective in terms of clinical progress of prostate.
For More Information:
Fish Consumption and Prostate Cancer Risk: A Review and Meta-Analysis
Publication Journal: American Journal of Clinical Nutrition, November 2010
By Konrad M Szymanski, David C Wheeler; McGill University Health Center, Montreal, Canada and National Cancer Institute, Bethesda, MD