top of page

The Big Fat Series IV - Omega-3 and Omega-6 Fatty Acids

Updated: Jul 11, 2021

Can you name a few foods that are rich in omega-3 fatty acids?

Fatty fish such as salmon, tuna, sardines, herring, mackerel and shellfish are great dietary sources of omega 3-fatty acids. If you prefer vegan or vegetarian sources, flax, chia, hemp seeds and walnuts provide plenty of alpha linoleic acid (ALA), however ALA cannot be used directly by our bodies. The human body can only convert up to 10% of ALA into the bioavailable forms of omega-3 fatty acids DHA and EPA for absorption. This means vegetarians and vegans may need to consume 10 to 20 times the recommended amounts to reach the equivalent bioavailable quantity. Fortunately vegan friendly omega-3 supplementation is available in the form of marine algae oils and algae is exactly where fatty fish get their omega-3s in the first place.

What are the benefits of omega 3 fatty acids? How relevant is it for runners?

Omega-3 fatty acids are not only important for pregnant women because they support foetal growth and neurological development in infants and children. For adults and non pregnant women, they are important for cognitive function, emotional state, cardiovascular and immune systems. For runners, whilst the intake of omega 3 may not directly improve athletic performance, it does help reduce inflammation, muscle soreness, and support the health of our heart, lungs, muscles and joints.

What about omega 6 fatty acids? Did you know the ideal omega-6: omega-3 ratio is 2:1?

Our ancestors from 500,000 years ago enjoyed a diet rich in omega-3 fatty acids because they hunted animals that foraged on plants and caught wild fish that fed on algae. This diet meant that our ancestors consumed omega-6 : omega-3 in a ratio of about 1:1. Whereas a typical modern diet full of grain-fed meat, farmed fish fed and processed food made or cooked with vegetable oils such as corn, canola and soybean lands us at an omega-6 to omega-3 ratio of between 20: 1 and 40:1!

How to improve our fatty acids ratio?

The simple answer is to eat more omega-3 rich foods such as wild-caught fatty fish, seafood, nuts and seeds.

Foods with the highest omega 3 to omega 6 ratios include snow crab, atlantic cod, tuna, mussels, broccoli raab, spinach, flaxseeds, mangos, lettuce and kidney beans.

In addition, we should limit or avoid packaged or processed foods such as deep fried, baked goods, cakes, pies and biscuits, or anything cooked with vegetable oils, as these are loaded with omega-6 fatty acids.

Click to read Part II and Part III of the Big Fat Series, Vegetable Oils and The Story of Trans Fats.

Omega-3 and Omega-6

Omega-3 (alpha linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)) and omega 6 fatty acids (linoleic acid, arachidonic acid) are common forms of polyunsaturated fatty acids (PUFA). These omega oils are called essential fatty acids because our bodies do not produce them. We must get them from our diet. Omega-6s are pro-inflammatory and omega-3s are anti-inflammatory.

Omega-6 Is Important For Our Survival

Inflammation may sound bad but omega-6 fatty acids is important for our survival. When you cut your finger or graze your knee, you bleed and your wound swells up. When we are injured or faced with acute illnesses such as infection, inflammation can be protective and help us heal. Whilst deficiency in omega-6 can affect our immune system and many biological processes in our body, most of us on a modern diet are more at risk of taking in too much rather than too little omega-6.

If you regularly dine out, eat takeaway meals, or consume deep fried, bakedor processed food like chips, pizzas, cakes, pies and pastries, or anything made with canola, corn and soybean oil, you are likely consuming too much omega-6 fatty acids. Excessive consumption of omega-6 fatty acids can contribute to chronic inflammation, depression and increase the risk of heart disease.

On the other hand, if you are concerned about not getting enough omega-6 fatty acids, the best sources of omega-6s are real foods such as sunflower seeds, pumpkin seeds, walnuts, sesame, chia and flax seeds.

An Ideal Omega-6: Omega-3 Ratio

An ideal omega-6 to omega-3 profile is 2:1. As mentioned early, the modern diet is usually ten or twenty times that. A diet rich in omega-6 and low in omega-3 can increase inflammation, the risk of heart disease and affect our mental health. You can improve this ratio by having more homemade, freshly prepared food in place of takeaways, deep fried and processed food containing vegetable oils. You can follow an anti-inflammatory diet rich in omega-3 fatty acids such as wild-caught fish, algae oil, flax seeds, hemp seeds, chia seeds and walnuts.

Various dietary recommendations suggest having fish two to three times a week, mainly because there are concerns over mercury contamination. However, you should feel safe to eat fish more often as long as you have access to clean sustainable sources of wild caught fish and seafood.

Click here to see how and where to buy clean seafood.

What is Omega-3?

Omega-3 fatty acids come in three forms, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). As mentioned above, humans are not able to synthesise omega-3 fatty acids, so we have to obtain them from our diet. Deficiency in omega-3 fatty acids is associated with increased cardiovascular risk, abnormal heart rhythm, depression and dementia.

Humans are unable to absorb ALA directly, so all dietary sources of ALA will need to be converted into EPA and DHA for absorption. Of the three omega-3 fatty acids, EPA and DHA provide the most benefits for our health such as anti-inflammation, visual and brain function.

ALA is found in abundance in plants such as chia seeds, flax seeds, hemp seeds, and walnuts, which many consider as important sources of omega-3 fatty acids for vegetarians. Unfortunately humans can only convert between 2% to 10% of ALA into active forms of EPA and DHA for the body to absorb. The conversion from ALA into EPA and then DHA also depends on vitamin B6, zinc and iron, which tend to be in lower supply and/or in less bioavailable forms in a vegetarian diet.

Even consuming large quantities of these seeds and nuts rich in ALA may not be enough to achieve optimal health. Marine algae oils, which contains both EPA and DHA, are the most effective omega-3 supplements for vegans and vegetarians.

DHA is the most prevalent fatty acid found in the brain and there is a relationship between red blood cells EPA and DHA and brain volumes associated with memory. DHA helps to maintain brain health and protect against inflammation. Higher consumption of DHA appears to improve mood, achieve insulin sensitivity, increased muscle growth and better sleep.

Sources of DHA and EPA

Sustainably caught fish such as salmon, sardines, anchovies, tuna, herring, egg yolks and grass-fed meats are excellent sources of EPA and DHA.

Wild-caught fish and grass fed meats are preferred because farmed animals are typically grain-fed soy and corn, which reduces the omega-3 contents in these foods. Fish and krill oils are great sources of DHA and EPA but it is important to watch out for contamination.

Mercury Contamination

Although fish and shellfish are wonderful and delicious sources of omega-3 fatty acids, we need to be aware of mercury toxicity. The situation is worse for species further up the food chain, such as king mackerel, swordfish, and ahi tuna. This is because larger species eat smaller fish and concentrate these contaminants via a process called biomagnification. Fish oils may also be contaminated with mercury and polychlorinated biphenyls (PCBs). When you next purchase fish oil supplements, try to opt products that have the highest purity, are independently tested and proven to have minimal contaminants

Further Information

1. Shulkin, M., Pimpin, l., Bellinger, D., Kranz, S., Fawzi, W., Duggan, C., Mozaffarian, D.; n-3 Fatty Acid Supplementation in Mothers, Preterm Infants, and Term Infants and Childhood Psychomotor and Visual Development: A Systematic Review and Meta-Analysis. The Journal of Nutrition; 2018 Mar 1; 148(3): 409-418.

2. Black, K.E., Witard, O.C., Baker, D., Healey, P., Lewis, V., Tavares, F., Christensen, S., Pease, T., Smith, B.; Adding omega-3 fatty acids to a protein-based supplement during pre-season training results in reduced muscle soreness and the better maintenance of explosive power in professional Rugby Union players. European Journal of Sport Science; 2018 Nov;18(10):1357-1367.

3. Cooper, R. E., Tye, C., Kuntsi, J., Vassos, E., Asherson, P.; Omega-3 polyunsaturated fatty acid supplementation and cognition: A systematic review and meta-analysis. Journal of Psychopharmacology; 2015 Jul; 29(7); 753-63

4. Cooper, R. E., Tye, C., Kuntsi, J., Vassos, E., Asherson, P.; The effect of omega-3 polyunsaturated fatty acid supplementation on emotional dysregulation, oppositional behaviour and conduct problems in ADHD: A systematic review and meta-analysis. Journal of Affective Disorders; 2016 Jan 15; 190:474-482

5. Abdelhamid, A. S., Brown, T.J., Brainard, J.S., Biswas, P., Thorpe, G. C., Moore, H.J., Deane, K.H., Al Abdulghafoor, F.K., Summerbell, C.D.,  Worthington, H. V., Song, F., Hooper, L.; Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.; Cochrane Database Systematic Review 2018 Jul 18;7(7):

6. Husson, M-O, Ley, D., Portal, C., Gottrand, M., Hueso, T., Desseyn, J-L., Gottrand, F.. Modulation of host defence against bacterial and viral infections by omega-3 polyunsaturated fatty acids. Journal of Infection, 2016 Dec;73(6):523-535

7. Kiecolt-Glaser, J. K., Belury, M. A., , Andridge, R., , Malarkey, W. B., Hwang, B. S., Glaser, R.,

Omega-3 supplementation lowers inflammation in healthy middle-aged and older adults: a randomized controlled trial. Brain Behav Immun, 2012 Aug;26(6):988-95.

8. Simopoulos, A.P.; The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases; Experimental Biology and Medicine 2008 Jun;233(6):674-88

9. Burns-Whitmore, B. , Haddad, E., Sabaté, J., Rajaram, S. "Effects of supplementing n-3 fatty acid enriched eggs and walnuts on cardiovascular disease risk markers in healthy free-living lacto-ovo-vegetarians: a randomised, crossover, free-living intervention study."; Nutr J; 2014 Mar 27;13:29.

10. Pottala, J.V., Yaffe, K,, Robinson, J.G., Espeland, M.A., Wallace, R., Harris, W.S.;"Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes. WHIMS-MRI Study."Neurology; 2014; Feb 4;82(5):435-42.

11. Cardoso, C., Afonso, C., Bandarra, N.M.; "Dietary DHA and health: cognitive function ageing." Nutr Res Rev; 2016 Dec; 29(2):281-294

12. Foods with a high omega-3 to omega-6 ratio

13. Foods high in DHA

14. Foods high in omega-6

322 views0 comments

Recent Posts

See All
bottom of page