Prostate cancer is a slow developing malignancy that can take decades to manifest as clinically-relevant disease. Commonly recognized risk factors for contracting prostate cancer are diet, body mass, race, family history, hormone status, and age.  Several scientific studies have found a reduction in prostate cancer associated with increased omega-3 intake. A recent report purportedly showed the opposite. This report was based on a single blood test of plasma fatty acids in a group of 834 men who were followed up to six years to assess prostate cancer risk (low- and high-grade disease). A smaller group of 75 men was followed up to nine years to assess only high-grade prostate cancer risk.

In a case analysis conducted by Life Extension staff, a healthy diet that included fish but not fish oil supplementation resulted in an omega-3 red blood cell (RBC) equivalence level of 6.06%.

However, a standard diet supplemented with 3.6 grams of EPA/DHA from purified fish oil resulted in an omega-3 RBC equivalence level of 10.59%. Thus, compared to what can be achieved with a healthy diet alone, adding a high quality fish oil supplement can nearly double a person’s omega-3 RBC equivalence score, which is consistent with the published literature.

Therefore, if participants in the report alleging an association with fish and prostate cancer had been taking meaningful doses of fish oil supplements, their levels should have been substantially higher than what the study authors reported. Instead, for men in the prostate cancer group of this study, the percentage of plasma long-chain omega-3 fatty acids was only 4.66% … a lower level than historic baselines taking no supplemental omega-3s.13

The numbers below should clarify this glaring flaw that renders conclusions from this report claiming fish or fish oil increases prostate cancer utterly meaningless:

  • Omega-3 RBC equivalence percentage of a moderate fish eater: 6.06%
  • Omega-3 RBC equivalence percentage when taking 3.6 grams/day EPA/DHA: 10.59%
  • Average long-chain omega-3 plasma percentage in study group with higher prostate cancer rates: 4.66%
  • Average long-chain omega-3 plasma percentage in study control group (no prostate cancer): 4.48%