Does Fish Oil Cause Cancer? What You MUST Know About Fish Oil!

The most widely consumed supplement in North America today is Fish Oil.  Fish Oil is a concentrated source of Omega-3 fats (EPA/DHA) and has been touted for it’s ability to reduce inflammation and has been proven effective in medical studies to reduce the risk of heart disease, joint pain, breast cancer and Alzheimer’s.

But a shocking new study published in the Journal of the National Cancer Institute has shown that men who consume the largest amount of fish oil have a 71 percent higher risk of (high-grade) prostate cancer and a 43 percent increase in all types of prostate cancer.  The study was conducted on 2,227 men of which 38% of the men had prostate cancer.1

According to researcher Theodore Brasky from the Ohio State University Medical Center, “These fish oil supplements in which some men are getting mega, mega doses, in our opinion is probably a little bit dangerous.”

What is a “Mega-Dose”?  The American Heart Association considers taking up to 3 grams of fish oil per day “safe”.  Most physicians would say that taking 2+ grams daily is a mega dose.

What You MUST Know About Fish Oil

So should you stop taking your fish oil immediately because of this study?  No.  But should you take a look at how much fish oil you take and what brand you take?  Yes.

But before we just into the type of Omega-3’s you should be getting, let’s talk about WHY fish oil could increase a man’s risk of prostate cancer.

The answer here is IMBALANCE.  Most people know that omega-3 fatty acids and omega-6 fatty acids need to have a balanced ratio.  Most studies conclude between a 1:1 and 4:1 ratio having slightly more omega-6 fats is ideal

The average american’s diet has a ratio that is probably somewhere closer to 17:1 which causes inflammation and risk on chronic illness.2

But, that doesn’t mean that you should go and take a “mega-dose” of fish oil every day.

Another thing I want to clear up is that Omega-6 fatty acids aren’t bad for you. In fact, if your diet contains too many omega-3 fatty acids, your immune system wouldn’t work very well.

That’s because omega-3 and omega-6 fatty acids are meant to work in a system of checks and balances. Omega-3 fatty acids suppress inflammation and omega-6 fatty acids promote inflammation which actually supports your bodies natural system of defense like activating your white blood cells.

So, if you consume too many Omega-3 fats (EPA/DHA) you can actually weaken your immune system.

Does it make sense now how overconsumption of Fish Oil and not getting the proper ratio of Omega-6 fats with them can cause prostate cancer?

Where to get your Omega-3’s and how much

Your best way to achieve balance is by getting your omega-3’s from food sources because if the animal has been raised right and plants grown right they already have a healthy ratio.  I still think it is beneficial for some to supplement with a high quality fish oil or cold liver oil but not over 1,000mg daily if you are eating healthy.

I also want to mention there are different types of Omega-3 fats which are ALA, EPA, and DHA.  ALA is found in certain nuts, seeds, and pastured animals where EPA and DHA are found in fatty fish like salmon.

In the study we have discussed they did not find a link between ALA (alpha linolenic acid) the type of omega-3 fat found in pastured animals and plants  and prostate cancer.

What is the difference between EPA, DHA, and ALA?

Your body really needs EPA and DHA for the anti-inflammatory benefits.  Your body can break down ALA into EPA/DHA but many can’t break it down very well.    Your body can convert anywhere from 8% to 60% of ALA into EPA and 5%-25% DHA.3  And that conversion factor really depends on your diet and health of your digestive tract.

That being said, I believe it is important to get all three types of Omega-3 fats in your diet on a regular basis.

For your best sources of Omega-3 rich foods I recommend

  1. Cold water fish like salmon, halibut, tuna, mackerel, and sardines
  2. Pasture raised beef, lamb, wild game, free-range eggs and raw dairy
  3. Chia seeds, flaxseed, hemp seeds, and walnuts
Wild Salmon1303380
Chia Seeds49151620
Grass-fed Beef100400
Pastured Eggs102558
Pastured Dairy130203

Meat sources 100g, Nuts/Seeds 28g, Dairy 1 cup

Benefits of Omega-3’s not to be forgotten

There is a large amount of research proving that omega-3’s reduce inflammation caused by excess omega-6 fatty acids, trans fats, toxins in the environment and other sources. Reducing inflammation reduces your risk of arthritis and heart disease. Omega-3’s are especially important for brain development, brain function and behavior.  Low levels of omega-3 fatty acids have been linked to dry skin, depression and mood swings, heart problems, fatigue, memory problems and poor circulation.

Scientific evidence for the benefits of fish oil is strongest in regards to helping heart disease, cholesterol levels and triglyceride levels.  Omega-3’s also lower blood pressure as well as normalizing heart rhythms, treating atherosclerosis and lowering risk of stroke. In fact, eating just two servings of fish a week can lower stroke risk by 50 percent.4

Preliminary studies suggest that omega-3’s may help improve symptoms of osteoarthritis and joint pain associated with inflammatory bowel disease may also be relieved with omega-3 supplementation.5 Joint pain in those with lupus may be reduced by omega-3’s.6  In terms of osteoporosis studies show that omega-3’s slow bone loss and increase bone density.7

Because of omega-3’s role in brain function, researchers have looked at whether omega-3 fatty acid supplements help relieve depression and many studies have proven its effectiveness.  Also, there is strong evidence that omega-3 fats improve ADHD and also help Alzheimer’s and other forms of cognitive decline and dementia.8

There are also several studies that suggest omega-3 ingestion can reduce the risk and slow the progression of colon cancer and lower the risk of breast cancer.9

Should I still take Fish Oil?

I think that if you are consuming wild caught fish a couple of times a week and have a diet high in pastured animals fats and plant based omega’s like chia and flaxseeds then taking an omega-3 supplement might not be necessary.

However, I follow the above diet and still on occasion do take a fish oil supplement.  BUT, I don’t just take ANY fish oil supplement.  I would consider many of the fish oil supplements available today to be unhealthily.  Buy a reputable brand and don’t take something you picked up at the drug store.

Look for fish oil supplements that contain anti-oxidants like astaxathin and rosemary to keep the oil from oxidizing.

When taking a fish oil supplement I would NOT typically take more than 1000mg daily.  Remember, the key is balance.  If you want all of the health benefits of omega-3 fats without any of the negative side effects get your omega’s from food sources and supplement with a mild to moderate of dose of fish on days that you do not consume wild caught fish.

This is the fish oil that I take.

Where do you get your Omega-3’s?


1 Brasky TM, Darke AK, Song X, Tangen CM (2013) ‘Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial’, Journal of the National Cancer Institute, 10(1093)174.

2 Simopoulos AP (2002) ‘The importance of the ratio of omega-6/omega-3 essential fatty acids’, Biomedicine and Pharmacotherapy, 56(8), pp. 365-79.

3 Harper CR, Edwards MJ, DeFilippis AP, Jacobson TA.  Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans. The Journal of Nutrition.2007;137(12):2816

4 “The Lipid Research Clinics Coronary Primary Prevention Trial Results. I. Reduction in Incidence of Coronary Heart Disease,” JAMA, 1984, 251:359

5 Ruggiero C, Lattanzio F, Lauretani F, Gasperini B, Andres-Lacueva C, Cherubini A.. Omega-3 polyunsaturated fatty acids and immune-mediated diseases: inflammatory bowel disease and rheumatoid arthritis. Current Pharmaceutical Design.2009;15(36):4135-48

6 Clark WF, Parbtani A, Huff MW, Reid B, Holub BJ, Falardeau P.. Omega-3 fatty acid dietary supplementation in systemic lupus erythematosus. Kidney International.1989;36(4):653-60

7 Maggio M, Artoni A, Lauretani F, Borghi L, Nouvenne A, Valenti G, Ceda GP.. The impact of omega-3 fatty acids on osteoporosis. Current Pharmaceutical Design.2009;15(36):4157-64

8 Hooijmans CR, Pasker-de Jong PC, de Vries RB, Ritskes-Hoitinga M.. The effects of long-term omega-3 fatty acid supplementation on cognition and Alzheimer’s pathology in animal models of Alzheimer’s disease: a systematic review and meta-analysis.. Journal of Alzheimer’s Disease.2012;28(1):191-209

9 Christian Nordqvist Medical News Today. Omega-3 Fatty Acids Slow Triple-Negative Breast Cancer Cell Proliferation. (accessed June 8 2013).

Josh Axe

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