A man who has high levels of PSA – prostate-specific antigen – has an elevated risk of getting prostate cancer. But your PSA levels do not determine whether you actually have or will get prostate cancer. A study in the April 17, 2013 medical journal "PLoS One" states that the chemicals in salted or smoked fatty fish increase the risk of prostate cancer, but the fish oil is actually cancer-protective. Research on fish oil and prostate cancer risk is conflicting.
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PSA and Prostate Cancer
A man’s prostate cells produce PSA. Your PSA levels naturally increase as you age. Doctors test PSA levels as a way to determine your risk for prostate cancer. If you have prostate cancer, doctors will test your PSA levels to judge the progression of the disease. No level of PSA is considered normal or abnormal, but your doctor will weigh your age, race and other factors as well as levels of PSA. General parameters for healthy PSA levels range from less than 2.5 nanograms per milliliter for men younger than 50 to less than 6.5 nanograms per milliliter for men older than 70.
Dr. Theodore Brasky and other researchers at the Fred Hutchinson Cancer Research Center found a link between fish oil consumption, higher PSA levels and prostate cancer. The seven-year trial included more than 3,400 men aged 55 to 84. The study found that men with higher levels of omega-3 fatty acids, the heart-healthy fats in fish oil, had higher levels of PSA than men with lower levels of omega-3 fatty acids. The DHA in omega-3 fatty acids put men at higher risk of an aggressive form of prostate cancer, but not of getting low-grade prostate cancer, according to the study published in the “American Journal of Epidemiology” in April 2011.
Brasky told "The New York Times" in a May 2, 2011, article that the results of his research surprised him. But he said the study, which also found men with high trans fatty acid levels at reduced risk of prostate cancer, does not mean you should change your diet. "A man's risk of dying of heart disease is much greater than his risk for high-grade prostate cancer, which is very rare.” A heart-healthy diet includes fish oil and other omega-3 fatty acids and eliminates most trans fat.
A simple blood test can measure your levels of PSA. You should not ejaculate within 48 hours of your test as it could could incorrectly raise your PSA levels. Some herbs and medications can also falsely lower your PSA levels. Tell your doctor in advance of the test about all prescription drugs and dietary supplements you take. Substances known to cause false PSA levels include finasteride, saw palmetto, nilutamide and dutasteride. If you take fish oil supplements, do not take more than 3 grams a day. Larger amounts may prevent your blood from clotting properly and could also elevate your low-density lipoporotein -- "bad" cholesterol.