Omega-3s and Impact on Prostate Cancer

Dr. Sears' Blog: Omega-3 Fatty Acids and Prostate cancer? Oh, really?

There was a recent publication suggesting that higher levels of omega-3 fatty acids are associated with a greater risk of prostate cancer 1. Of course, the immediate media response was to indicate that taking fish oil supplements is dangerous. Of course, let’s not forget, then, that eating fish must also be dangerous.

Before letting the media focus on sound bites, a realistic first step might be to analyze the data and use some common sense to see if it justifies the headlines.

Everyone in the cancer field agrees that inflammation drives cancers. I believe the best marker for inflammation is the AA/EPA ratio as I have outlined in my various books for more than a decade. The reason is simple: As the AA/EPA ratio decreases, you make fewer inflammatory hormones (i.e. eicosanoids coming from AA) and more anti-inflammatory hormones (i.e. resolvins coming from EPA). Bottom line, this means less inflammation in the body. So let’s look at the fatty acid data as percent of the total fatty acids that was presented in this article that were associated with no development of prostate cancer, total prostate cancer incidence, and breaking of the total cancer group into either low-grade or high-grade cancer 1.

Non-cancerCancerLow-grade cancerHigh-grade cancer

Having decades of experience of doing fatty acid analyses, I can tell that these numbers are clinically insignificant. What does that mean? The numbers are basically the same. They might be statistically significant, but the differences definitely are not clinically relevant.

I have been very consistent over the years in stating that to have an impact on reducing inflammation, you have to have EPA levels greater than 4% of the total fatty acids, AA levels less than 9% of the total fatty acids and an AA/EPA ratio between 1.5 and 3. As you can see, the subjects in this article were nowhere close to those parameters. In fact, I would say all the subjects in this trial were identical relative to AA, EPA and the AA/EPA ratio. In other words, the analysis is meaningless.

Is there any population in the world that may have the ranges that I recommend? The answer is the Japanese population. Their levels of EPA are about 3% of total fatty acids, and they have an AA/EPA ratio of about 1.6 2. The JELIS study was a long-term study (3 ½ years) of 18,000 Japanese with high cholesterol levels given extra omega-3 fatty acids to lower their AA/EPA an even lower ratio. With this lower AA/EPA ratio (now 0.8), their cardiovascular events were reduced by 20% with no increase in any type of cancer. Likewise, high levels of omega-3 fatty acids have been used as prescription drugs for the treatment of elevated triglyceride levels with absolutely no reports of any increase in any type of cancer.

This is where common sense hopefully comes into play. If the conclusion of the article was correct that higher levels of omega-3 fatty acids increase prostate cancer, then the Japanese male population should be decimated with prostate cancer. So what are the facts? The Japanese have one of lowest rates of prostate cancer incidence in the world. In fact, their rate of prostate cancer incidence is 10 times lower than the United States 3. More importantly, the mortality from prostate cancer is also about 5 times less in Japan than in the United States 4. I emphasize the word mortality since prostate cancer is usually very slow growing so that males usually die with prostate cancer, not because of it. This is why the recent recommendation is to dramatically reduce the screening for prostate cancer because the harm of treatment usually outweighs the benefits of detection.

Common sense (and a little understanding of the biochemistry of inflammation) says that if you reduce inflammation (determined by your AA/EPA ratio), then your likelihood of living longer is greatly increased. The best way to reduce AA is to follow a strict Zone Diet. The best way to increase EPA is to take adequate levels of purified omega-3 fatty acids rich in EPA. It is obvious the subjects of this study were doing neither.


  1. Brasky TM, Darke AK, Song X, Tangen CM, Goodma PJ, Thompson IM, Meyskens FL, Goodman GE, Minasian LM, Parnes HL, Klein EA, and Kristal AR. “Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial.” J Nat Cancer Inst DOIL10.109393 (2013).
  2. Yokoyama M, Origasa H, Matsuzaki M, Matsuzawa Y, Saito Y, Ishikawa Y, Oikawa S, Sasaki J, Hishida H, Itakura H, Kita T, Kitabatake A, Nakaya N, Sakata T, Shimada K, and Shirato K. ” Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis.” Lancet 367:1090-1098 (2007).
  3. Haas GP, Delongchamps N, Brawley OW, Wang CY, and de la Roza G. “The worldwide epidemiology of prostate cancer: perspectives from autopsy studies.” Can J Urol 15: 3866-3871 (2008).
  4. Marugame T and Mizuno S. “Comparison of Prostate Cancer Mortality in Five Countries: France, Italy, Japan, UK and USA from the WHO Mortality Database (1960–2000).” Jpn J Clin Oncol 35: 690–691 (2005).

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About Dr. Barry Sears

Dr. Barry Sears is a leading authority on the impact of the diet on hormonal response, genetic expression, and inflammation. A former research scientist at the Boston University School of Medicine and the Massachusetts Institute of Technology, Dr. Sears has dedicated his research efforts over the past 45 years to the study of lipids. He has published 40 scientific articles and holds 14 U.S. patents in the areas of intravenous drug delivery systems and hormonal regulation for the treatment of cardiovascular disease. He has also written 14 books, including the New York Times #1 best-seller, The Zone, which have sold more than 6 million copies in the U.S. and have been translated into 22 different languages.


  1. Ted Weidlich

    Dr. Sears, I have been on the zone diet for about 10 years. My aa/epa ratio has always been between 1.5 and 3. My urologist is going to biopsy my enlarged prostate for cancer prior to surgery to reduce it. My question is, if there was is cancer in my prostate or anywhere else in my body, wouldn’t my cellular inflammation be elevated above 3? Thank you.

  2. anwar

    Hello doctor.I have purchased your book and have been reading it with a lot of interest.My issue is that I have been following diet of Dr Raymond peat.I have been having a lot of fruit juices and milk and sugar.Also very low polyunsaturated fats.My skin became very dry however (along with some male issues)I followed his diet due to the fact I have suffered from neck cancer in the past and the doctor basically recommends no Pufa ( including fish oil and says very bad for the body.)could you please tell me if fish oil is as dangerous as dr peat states.I really like the way you write and it seems very logical.I am very concerned with skin aging(have had radiotherapy) and dr peat basically says that all PUFA will cause skin aging.I am as you can appreciate very anxious and confused.Thanks for the great book

  3. Gabriel

    Dr. Sears, I was thinking about the ratio AA/EPA that results from following the zone diet.
    For example, if you supplement with 1600 mg of EPA, and if you eat 3 ounces of salmon, that is another 1000mg of EPA. On the other hand, the levels of AA that you advice in your recipes are very low: from 4 tea spoons of olive oil results in 10 % of its content, and in walnut it is 51%, almonds 24% and in eggs only 16% (wiki) . But you don’t recommend eating yolks. It is a miscalculation?. Please, in your books, you have to explain better how much fatty acids are in every meal. This is an essential issue but you overlook it. As you have said moderation is the rule, but how can you advocate walnut instead of yolks? I see here there is a disproportion.

    • Dr. Sears

      Our AA/EPA ratio test removes all of those speculations. Most individuals have a high levels of AA (greater than 9% of total fatty acids). That’s why I don’t recommend eating egg yolks that are rich in AA. Most people are low in EPA (less than 4% of total fatty acids regardless of their fish intake. Of the food sources that you mention, only egg yolks contain any AA. I have written extensively on this in my many books including one entire book devoted to the subject, The OmegaRx Zone. Once you have your AA/EPA ratio, then you can begin to make rational choices about fatty acid supplementation.


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