Prostate Cancer and Fish Oil–Making Sense Out of Headline-Induced Confusion

A scientific paper was published this week in the Journal of the National Cancer Institute, which induced wide spread concern for people taking fish oil supplements, despite the fact that this study wasn’t even about supplements. First, let me clarify this study and another related study, then I’ll share why I think men should keep taking their fish oil, and finally, I’ll share several take home points to reduce prostate cancer risk.

This article is part of the SELECT Trial, a study evaluating the effects of selenium and alpha tocopherol on prostate cancer. This study was NOT designed to clarify the risk or benefits of fish oil and/or fish intake on prostate cancer risk. In this study with 35,500 subjects, they were given either a placebo, alpha tocopherol (one of the 8 forms of vitamin E, which appears to increase prostate cancer risk) and/or selenium (a mineral, which seems to decrease prostate cancer risk). Two percent of the subjects developed prostate cancer during the study, and less than one percent developed high grade (aggressive prostate cancer). Those subjects with the highest long chain omega-3 blood levels had higher rates of prostate cancer than those with lower levels. In particular the fatty acids EPA and DHA were associated with an increased prostate cancer risk.  There are other studies that have also shown a relationship between blood levels of EPA and DHA with prostate cancer, so this is just the latest study making this observation. But to put this in perspective, something that increases the relative risk by 70% if the actual risk is less than 1% is still a very small risk. This same study also noted that trans fat (which normally causes cancer, heart attacks, strokes, diabetes, and Alzheimer’s) decreased the risk for prostate cancer–although nobody is going to recommend that you eat this toxic fat to lower prostate cancer risk.

There are serious problems with this type of study if you hope to draw any conclusions:

  • First, this study can’t distinguish between eating fish or taking a fish oil supplement.
  • Second, the study could not tell the difference between eating wild fish, versus fish intake from farm raised fish raised in polluted waters that might be packed with carcinogens.
  • Further, cheap fish oil that is commonly sold in the USA is loaded with rancid fats (lipid peroxides) and these bad fats are believed to cause cancer.

For years, I have believed that taking a cheap fish oil supplement puts people at risk for cancer. This study certainly cannot distinguish between good fish oil intake and bad fish oil intake. Consider that close to 90% of fish oil produced in the USA is illegal in Europe because the quality is so bad. For hints on selecting good quality fish oil, please see my related article on fish oils.

As noted 3-4 other studies have shown similar findings between EPA and DHA blood levels and prostate cancer. Yet importantly, one of these studies was able to distinguish between fish oil intake and fish intake. A study by Torfadottir JE et al, PLoS One 2013 April 17;(8(4) compared fish intake and fish oil intake separately with prostate cancer risk in 2268 men in Iceland. In this study, high qualify fish oil was shown to decrease the risk for prostate cancer (this was a European study that has quality standards for fish oil). Eating salted and smoked fish was shown to increase prostate cancer risk. (I don’t know the quality of fish and whether it was farm raised or wild in this study).

The bottom line is that high quality fish oil has several health benefits that include:

  • Less risk for heart attack and stroke, especially in people with known cardiovascular disease
  • Improved brain performance and speed, and likely a lower risk for Alzheimer’s disease
  • Decreased inflammation and improvement in arthritis symptoms (It sure makes my joints feel better!)
  • Decreased risk for auto-immune diseases, such as skin conditions and inflammatory bowel disease

However, in light of these studies, even though the benefits likely outweigh the risks, there is the chance that fish oil intake may increase prostate cancer risk slightly. To offset this potential risk, follow these steps:

  1. Avoid eating farm raised fish unless you know its source and feed.
  2. If you take fish oil, pay a little extra for high quality fish oil, or skip it. Don’t risk taking cheap, rancid fish oil.

Additional tips to reduce your risk for prostate cancer, and/or to improve your outcome if you get prostate cancer include:

–         Plan for a yearly prostate check and PSA level (for men starting age 40, and when you have less than 15 years to live, stop screening, as prostate cancer takes that long to kill you).

–         Ensure at least ½ cup of Mariana sauce (tomato sauce) weekly (for the lycopene).

–         Enjoy 1 cup of cruciferous veggies (broccoli, bokchoy, cauliflower, cabbage, kale, Brussels sprouts) daily.

–         Get your blood sugar levels to normal, as elevated levels are associated with a higher risk for prostate cancer, likely as high blood sugars increase insulin growth factor levels which stimulates cancer growth.

–         Ensure adequate vitamin D, around 1,000-2,000 IU daily. Your vitamin D level should be minimally above 32 and preferably 40-70.

–         Consider taking curcumin as a supplement, 500 mg / day orally


To Your Health!

One Comment On “Prostate Cancer and Fish Oil–Making Sense Out of Headline-Induced Confusion”

  1. Great expose and commentary on the current state of fish and fish oils. Thank you!

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