Does Fish Oil Really Cause Prostate Cancer? Debunking the Myth

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fish oil prostate cancerA 2013 study published in the Journal of the National Cancer Institute suggests that there is a higher risk of prostate cancer for men who consume omega-3 fatty acids.

Because I have always encouraged patients and friends to get plenty of omega-3 fatty acids, I wanted to pose the question: can fish oil cause prostate cancer? But first, let’s take a look at what the study found.

The Study

First of all, fish oil supplements contain omega-3 polyunsaturated fatty acids. Omega-3 polyunsaturated fatty acids benefit the body by reducing the body’s production of triglycerides. Triglycerides are a type of fat in your blood, and if the levels are too high, your chances of experiencing a heart attack can increase.

Now let’s look at the study; it was conducted at the Fred Hutchinson Cancer Research Center in Seattle, WA, and researchers claim that there is a link between increased blood levels of omega-3 fatty acids and prostate cancer cases.

However, the research also indicates that higher levels of omega-6 fatty acids, which the majority of Americans consume too much of, was surprisingly associated with a lower risk of developing prostate cancer.

These findings suggest that the more fish or fish oil a man incorporates into his diet, the higher his chances of developing prostate cancer. The results further indicate that consuming higher doses of omega-6 fatty acids could be beneficial.

A Closer Look

To investigate their theory, researchers used data from a previous study that was conducted in 2011, called SELECT (Selenium and Vitamin E Cancer Prevention Trial). It’s important to note that the original SELECT study did not share the same objective as the most recent study—meaning, the original study wasn’t conducted to determine whether or not fish oil led to prostate cancer. Since both studies don’t strive for the same goal, it raises the question as to whether or not the 2011 study is relevant to the most recent study.

Furthermore, the current study does not prove cause and effect. For example: if this study had been an intervention type of study, where half of the participants were given fish oil and the other half a placebo and were followed for 20 years to see if they developed prostate cancer, then you would be able to see if the two were connected.

Another issue with the study is that the researchers did not distinguish where the participants were getting their omega-3 fatty acids from. Did they get it from eating fatty fish, or did they get it from taking supplements? Also, researchers did not state when the patients started using the fish oil. Did they start using it as a therapy once they were diagnosed with prostate cancer, or had they been taking it the whole time?

What about other factors that can lead to the progression of cancer? Smoking, bad nutrition, environmental toxicity, and stress—none of these factors were taken into account at any point during the study. We should ask other pertinent questions: Were these men exposed to heavy metals and toxins from eating mercury-rich fish, which can cause cancer? Did these men smoke or drink excessively? Could there have been a history of prostate cancer in the family?

The final flaw I found in the study is the way the researchers gathered the data. They analyzed blood plasma instead of red blood cells—and they did it with one single blood draw. If they used red blood cell samples, they would have gotten a more accurate assessment over the long-term, mainly because blood plasma provides more accurate short-term assessments.

Proven Health Benefits of Fish Oil Supplements

1. Reduces anxiety: A study published in the European Journal of Neuroscience revealed that fish oil reversed depression and anxiety-like behavior in rats; researchers also discovered that omega-3 fatty acids help regulate the flow of hormones and other chemical messengers, which can affect our moods.

2. Treats arthritis: Research shows that taking fish oil combined with borage seed oil can lead to reductions in rheumatoid arthritis.

3. Reduces ADHD symptoms: Fish oil has the potential to reduce common symptoms of ADHD, based on the effect it has on the brain. Sixty percent of the brain consists of composed fats with the most important being polyunsaturated omega-3 and omega-6 fatty acids.

4. Reduces cancer risk: Docosahexaenoic (DHA) and Eicosapentaenoic acid (EPA) can help reduce the risk of prostate cancer. They have also been found to help kill colon and breast cancer cells as well.

5. Slows cognitive decline: The fatty acids found in fish oil can slow down cognitive decline and help prevent brain atrophy in older adults. The oils help protect the hippocampus cells from being destroyed, which also reduces the risk of diabetics developing a cognitive disorder.

6. Treats depression: A study published in the journal Nutritional Neuroscience studied the effects of fish oil supplementation in adolescents who suffered from major depression. Researchers discovered a 40% decrease in depression symptoms as well as improvements in amino acid content in the brain, which can help balance brain chemicals.

7. Immune power: If you combine the antioxidant astaxanthin with fish oil, you will multiply its immune boosting power.

Aside from the common health benefits of fish oil, there are additional benefits that you can get from fish oil, which include the following:

  • Fish oil can be incredibly beneficial for the body’s largest organ: the skin. The necessary fat and vitamins that it contains promotes smooth skin by reducing inflammation.
  • Fish oil is beneficial for pregnant women and their children. The omega-3 fatty acid helps with the development of the brain, nervous system, and eye sight of the infant, and has also been known to reduce the risk of miscarriages.
  • Research indicates that fish oil reduces the fat proportion in the abdominal area when combined with exercise.
  • Fish oil has the potential to increase fertility in women by balancing hormones, reducing inflammation, and regulating their cycles.
  • The lack of DHA and EPA in your diet can lead to dandruff, thinning hair, and eczema. The fatty acids found in fish oil keep the skin moist; but if the DHA and EPA levels are low, too much moisture will leave the skin.

Based on the numerous health benefits and lack of evidence from the study, I will continue to recommend fish oil to patients and friends.

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Sources for Today’s Article:
Hyman, M., “Can Fish Oil Cause Prostate Cancer?” Dr. Hyman web site, last updated November 21, 2014;, last accessed September 9, 2015.