Omega-3 Fatty Acids and Prostate Health
Elucidating nutrient-health relationships is challenging. Once again, the news cycle will contribute to our confusion. Last summer, Brasky and colleagues published a paper and headlines associated omega-3 fatty acids with increased prostate cancer risk. Then editorials and scientific reviews claimed the link was unproven. Prediction: today’s main citation will generate headlines that omega-3 fatty acids reduce the risk of prostate cancer.
Moreel and colleagues hypothesized that omega-3 fatty acid concentrations in prostate tissue would be more strongly related to prostate cancer risk than omega-3 fatty acid concentrations measured in red blood cells or estimates of omega-3 fatty acid intake. They present baseline data from a 48 untreated men affected with low-risk prostate cancer. They report that omega-3 fatty acid concentrations, especially eicosapentaenoic acid (EPA) concentrations, measured in biopsied prostate tissue may be protective against prostate cancer progression.
What explains the different interpretations ? Dietary intake records reflect food patterns over the past few days, not nutrient status. Intake records are confounded by poor food databases, inherent variability in the nutrient content of foods, and accuracy of human recall. A single baseline blood, a measured by Brasky and colleagues, is a poor indicator of prostate omega-3 status. As discussed by Dr Joel Furman, measuring omega-3 fatty acids in blood is a better means of assessment than dietary records but not as effective as measuring omega-3 concentrations in red blood cell membranes. Still, omega-3 fatty acid measurements in red blood cell membranes have limitations because their 90 day lifespan. Moreel and colleagues directly measured omega-3 fatty acid concentrations in the prostate. They are measuring nutrient status in the tissue of interest. This is the best approach.
In summary, our advice hasn’t changed. Most people are not consuming enough omega-3 fatty acids. Diets are often unbalanced with respect to fatty acid types (omega-6 fatty acids, saturated fatty acids, trans fatty acids). Experts recommend 250-500 mg of EPA and DHA daily.
Moreel X, Allaire J, Leger C, Caron A, Labonte M-E, Lamarche B, Julien P, Desmeules P, Tetu B, Fradet V. Prostatic and dietary omega-3 fatty acids and prostate cancer progression during active surveillance. 2014 Cancer Prev Res doi: 10. 1158/1940-6207.CAPR-13-0349
Brasky TM, Darke AK, Song X, Tangen CM, Goodman PJ, Thompson IM, Meyskens Jr FL, Goodman GE, Minasian LM, Parnes HL, Klein EA, Kristal AR. Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial. 2013 JNCI doi:10.1093/jnci/djt174
MacKay D, Ritz BW. Do fatty acids really increase risk of prostate cancer? Evaluating the results of the recent report from the SELECT trial. 2013 Natural Med J Aug 5:8