Omega-3 Fatty Acids: Friend or Foe?

Omega-3 Fatty Acids: Friend or Foe?

The nutritional science community has caught our attention once again! My ears perked up when I read the headline, “A confirmed link between omega-3 fatty acids and increased risk of prostate cancer.” As a nutritionist, it's my job to be skeptical anytime I hear major health news hit the mainstream media, so I was curious what science researchers used to arrive at this conclusion and the method and processes of the study itself. My loved ones are currently consuming foods rich in omega-3s, so I needed to know all I could.

According to a study published in the Journal of the National Cancer Institute, supplementation with omega-3 fatty acids may be harmful. This comes on the coattails of two similar findings, one by the same group in 2011. However, what isn't emphasized is that the authors of this study did not assess any of the participants' dietary intake of fatty fish or omega-3 nutritional supplements - the study's conclusions are based wholly on the results of a single blood test.

What exactly does that mean? The omega-3 levels in your blood are subject to significant day-to-day variability just by means of natural physiology and this finding came retrospectively from a large randomized, placebo-controlled trial to test whether selenium and vitamin E, either alone or combined, reduced prostate cancer risk, not from a study with the intention of measuring Omega-3 effects on the prostate.

We do know from previous, more well-designed research studies that the addition of nutritional supplements, especially from fat-soluble vitamins, such as vitamin E and A and certain minerals like iron, may lead to excess levels in the body and has potential for negative effects. Drawing on this knowledge, remember that it's best to obtain nutrients through natural, whole foods and leave supplements to do their job, which are to “supplement” an otherwise healthful diet. Your body has a fantastic regulatory mechanism for nutrient balance when intake comes from whole food sources, whereas taking an unnecessary supplement could potentially introduce excessive amounts of a solitary nutrient. Eating quality food has not been proven dangerous unless contaminated during processing or by some mishap of modern agricultural practices.

Omega-3 fatty acids, especially EPA and DHA, most notably found in cold-water fish like salmon, have appeared as dietary angels in various research studies on heart health, brain health, anti-inflammatory, glowing skin, and weight loss studies alike with glowing accolades.

While omega-3s are all the rage, balance is key. The World Health Organization promotes an ideal balance between omega-6 fatty acids and omega-3 fatty acids of about 4:1. A healthy balance (some health care professionals aim for a lower ratio like 3:1 or 2:1) will support the immune system – an important part of our body’s defense against cancer.

Omega-6 fatty acids work with omega-3s in a system of checks and balances. Omega-3s suppress inflammation, while omega-6s promote inflammation, supporting our body’s natural system of defense, doing things like activating your white blood cells when needed. The Standard American Diet (SAD) is filled with processed foods loaded with ingredients high in omega-6s. So instead of adding a fish oil supplement to promote balance, try ditching some of those packaged foods containing high amounts of omega-6 rich ingredients like soy, corn, cottonseed, safflower and sunflower oils and opt for whole foods that naturally contain an ideal ratio of these two omegas.

(Fish sources 100g, Nuts/Seeds 28g)

If taking a supplement, the American Heart Association considers up to 3 grams per day a “safe” dosage; however, most physicians suggest staying below 2 grams per day. If consuming rich omega-3 sources through your diet, you may not need any more than one gram a day, if any at all. Be sure to check with your doctor about your appropriate dietary intake.

So should you ditch your omega-3s based on this study?

We wouldn't go that far. However, this is a good opportunity to discuss options with your healthcare provider, assess your diet and make sure you’re getting enough natural omega-3 fatty acids from whole food sources and not too many omega-6s, then decide if a supplement is appropriate.

There are just too many studies touting the positive benefits of these essential fatty acids to rid your diet of them altogether. Below are a few studies showing the positive benefits of omega-3 fatty acids when eaten in the appropriate amounts and from whole food sources like hemp seeds, flax seeds, chia seeds, wild salmon, walnuts, and algae. In addition, data related to omega-3 fatty acids and prostate cancer occurrence is inconsistent and reviewing the broad range of health benefits attributed to omega-3 fatty acid consumption leads me to believe that these little fatty acids are here to stay.


A Prospective Study of Dietary Alpha-linolenic Acid and the Risk of Prostate Cancer (United States)

Conclusion: In this prospective study of predominantly Caucasian men who were screened annually for newly incident prostate cancer, dietary intake of total ALA and ALA from specific food sources was not associated with risk of total prostate cancer or prostate tumors that were defined by stage and grade.

Consumption of Fish Products across the Lifespan and Prostate Cancer Risk

Conclusion: According to this study, salted or smoked fish may increase risk of advanced prostate cancer, whereas fish oil consumption may be protective against progression of prostate cancer in elderly men. In a setting with very high fish consumption, no association was found between overall fish consumption in early or midlife and prostate cancer risk.

Effects of Omega-3 Fatty Acids on Cancer Risk: A Systematic Review of 38 articles

Conclusions: A large body of literature spanning numerous cohorts from many countries and with different demographic characteristics does not provide evidence to suggest a significant association between omega-3 fatty acids and cancer incidence.

Omega-3s (PUFAs) and Breast Cancer Risk

Conclusion: This study showed consumption of most types of polyunsaturated fatty acids (PUFAs) -- but not fish itself -- was linked with a lower risk of breast cancer. Women with a high intake of PUFAs had a 14 percent reduction in breast cancer risk. For every 0.1-gram-per-day increase in the intake of the fatty acids, there was a 5 percent lower risk of breast cancer, the study found.

Omega-3s and Heart Disease

Conclusion: Although a short study, researchers found data extending the growing evidence that fish oil—specifically the omega-3 fatty acids—may have positive health benefits on neural cardiovascular control in humans. Fish oil lowers stress response of the heart.

Omega-3s and Inflammation

Conclusion: By virtue of their anti-inflammatory action, omega-3 polyunsaturated fatty acids (PUFA) may be beneficial in inflammatory diseases, according to this study. A large body of evidence supports a protective effect of omega-3 PUFA in experimental animal and ex-vivo models of Crohn's disease (CD), Ulcerative colitis (UC) and Rheumatoid arthritis (RA). Although fish oil supplementation in patients with IBD results in omega-3 PUFA incorporation into gut mucosal tissue and modification of inflammatory mediator profiles, the evidence of clinical benefits of omega-3 PUFA is weak. On the other hand, more convincing data support the efficacy of omega-3 PUFA in reducing pain, number of tender joints, duration of morning stiffness, use of non-steroidal anti-inflammatory drugs and improving physical performance in RA patients.

Reputable Omega-3 supplements:

  • Body Bio’s Kirunal 500mg 3:1 EPA/DHA
  • Nordic Naturals is a good OTC for fish oil as well as vegetarian algae-based omega-3s
  • Xymogen, Designs for Health, and Pure Encapsulations are three professional brands
Registered Dietitian

Comment by agrihawg
July 31, 2013
My doctor has told me to completely eliminate the fish oil supplement I was taking. However I eat tuna about 3 to 5 times a week. Is this enough to maintain adequate levels of Omega 3 in my diet?
NutriLiving Krista Haynes on July 31, 2013
The answer to this Q has many variables. If eating canned tuna, this link will help explain: For whole fish, check out this table: Health organizations suggest an EPA+DHA intake of at least 250 to 500 mg per day. So looks like you are probably meeting the suggested amount omega-3s. However, some species of tuna fish contain higher than desired amounts of mercury. Here's a handy guide to show how often you may want to eat tuna: For other sources of omega-3s try some of the plant-based options noted in the above article. In addition, you can find algae-based DHA and EPA supplements that are void of any harmful heavy metals.
In your chart, you have Walnuts listed as having a huge amount of Omega-6, which you state promotes inflammation. But I've also read on this site that Walnuts were good at reducing inflammation. Is the chart in this article correct? -Steve
NutriLiving Krista Haynes on July 17, 2013
Yes, Steve, the chart is correct. It is stated in milligrams. I understand your concern and appreciate your question. Let me explain... What I'd like to stress is that the ratio of omega:3s to omega:6s is based on your overall diet. If you are consuming nuts (which shouldn't be the base of ones diet, but used as a snack/condiment) and let's say you usually opt for almonds which have 0 omega-3s and 0.5g Omega-6s (0:1 ratio), then instead choose walnuts with a 0.24:1 ratio which is a more ideal ratio. We cannot isolate nutrients, but must look at things as a whole and consider the other nutrients contained in nuts. Nuts have been shown by research to be heart healthy (plus other benefits) due to a variety of nutrients and phytochemicals they contain so for us to discard them due to a higher omega-6 level would be doing ourselves a disservice. My point was that by choosing whole foods, we can optimize our fatty acid intake and by shunning processed foods that are loaded with oxidized omega-6 fatty acids (from the heat and air exposure), we can create a balance within our bodies. Remember, we do need omega-6 fatty acids in our diet as these too are ESSENTIAL fatty acids. The body also constructs hormones from omega 6 fatty acids. In general, hormones derived from the two classes of essential fatty acids have opposite effects. Those from omega-6 fatty acids tend to increase inflammation (an important component of the immune response like I mentioned), blood clotting, and cell proliferation, while those from omega-3 fatty acids decrease those functions. Both families of hormones must be in balance to maintain optimum health.
Thanks Krista, I had to think hard about what you were saying and stare at the chart with a dumb look on my face, but I think I'm starting to understand. It's just that everything else on the chart was higher in Omega-3s and it seemed odd that Walnuts would be the opposite. Especially since they are listed in a lot of Anti-inflammatory recipes. Hard to believe when they are so high in Omega-6s. -Steve
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