From foodconsumer.org
Omega-3 fatty acids, oily fish fight prostate cancer
By Sue Mueller - fc writer
Mar 24, 2006, 23:22
Eating oily fish or taking omega-3 fatty acids supplements may help prevent the spread of aggressive prostate cancer to other parts of the body while high intake of omega-6 fatty acids may do the opposite, according to a new UK cancer study.
The study, published online in the March 27 issue of British Journal of Cancer, found that the type of fatty acids determines how they influence the risk of metastatic prostate cancer. The UK researchers found Omega-3 fatty acids inhibit proliferation of prostate cancer cells whereas Omega-6 poly-unsaturated fatty acid, known as Arachidonic acid, promotes the proliferation of malignant prostate epithelial cells.
Epidemiological studies have already established not only an association between high intake of dietary fats and an elevated risk of developing metastatic prostate cancer, but also found that the types of fat intake affects the risk of the disease.
The researchers do not know how aracidonic acid influences the migration of cancer cells. They found the Omega-6 fatty acid at a high level such as 5M stimulates malignant epithelial cellular invasion, which may drive the cancer to bone marrow, according to the study. In contrast, omega-3 fatty acids or omega-3 poly-unsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid at a ratio of one part of omega-3 fats to two parts of omega-6 fats inhibit the process.
"This invasion was blocked by omega-3 fats - the ones found in oily fish. It is possible to have a healthy balance of these two types of fat - we only need about half as much omega-3 as omega-6 - that will still stop cancer cells from spreading," Mick Brown, Ph.D., lead author of the study from the Paterson Institute in Manchester, UK, was quoted as saying.
Noel Clarke, principal investigator of the study, from the Christie Hospital, said, as mydna.com quoted, "We think tumors may exploit the omega-6 fats as a high energy source - giving them the energy they need to maintain a high growth rate - and to create important signaling molecules. Omega-3 fats are known to interfere with the various functions of omega-6 fats, something confirmed by our findings. This effectively removes the cancer's 'free lunch', a fact that may have clinical importance"
Clarke suggests eating a diet with the right ratio of omega-3 and omega-6 fatty acids may help keep prostate cancer within the prostate gland where it can be easily and safely treated with surgeries and conventional therapies. Cancer Research UK recommends that people eat a health diet, high in fiber, fruit and vegetables and low in red and processed meat, to reduce risk of cancer.
"Diet is a factor in many types of cancer, but its potential role is not yet fully clear in prostate cancer. This research shows an effect in the laboratory. However, we would need large population studies to provide the needed evidence to say a change in diet could reduce prostate cancer cells from spreading," John Toy, M.D., Ph.D., medical director of Cancer Research UK, was quoted as saying.
The study, funded by the Association for International Cancer Research (AICR) and the Medical Research Council (MRC), was performed on prostate cancer cell cultures. The results may or may not be applicable to prostate cancer in humans. Further studies are needed to confirm the effects of omega-3 fatty acids and omega-6 fatty acids on the progression of prostate cancer.
Omega-3 and omega 6 fatty acids are two main groups of polyunsaturated fatty acids commonly found in foods. Both types have a positive role in keeping humans' health. Omeg-3 fatty acids are abundantly present in oily fish including salmon, mackerel, lake trout, herring, sardines and albacore tuna, consumption of which has been linked with a lower risk of certain cancers. Omega-6 fatty acids were richly found in vegetable oils such as corn oil, which was found to raise risk of cancers such as l ung cancer and b reast cancer.
In the United States, people consume much higher omega-6 fatty acids than omega-3 fatty acids, approximately at a ratio of one omega-3 fats to16 parts of omega-6 fats, a fact that prompts some to believe that the low ratio may be a cause for the high incidence of cancer in the country.
Prostate cancer is the most common form of cancer among men in the US, and it is second only to lung cancer as a cause of cancer-related death among men. The American Cancer Society estimates that approximately 220,000 new cases of prostate cancer are diagnosed and 29,000 men die of the disease every year, according to the Centers for Disease Control and Prevention.
Source: M D Brown et al., 2006, Promotion of prostatic metastatic migration towards human bone marrow stoma by Omega 6 and its inhibition by Omega 3 PUFAs, British Journal of Cancer (2006) 94, 842-853.
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