The word is out regarding the health benefits of Omega-3. It is part of every cell in our bodies and research indicates that it is crucial for the development and maintenance of normal brain function as well as vision. It is thought to affect the speed and quality of communication between nerve cells, not only this, but there is also well established evidence on its ability to reduce many risk factors for the development of heart disease. So if you would like know how to best optimise your levels of this essential fatty acid including signs of deficiency, what to consider when selecting your fish, how to choose your supplement or even the best vegetarian and vegan options, this post is for you.

Are we getting enough Omega-3s?

While it is possible to measure levels using a finger prick test, some signs that you are not getting enough may include:

  • Difficulty with concentration
  • Memory issues
  • Mood swings or anxiety
  • Disordered sleep
  • Allergies, asthma and hay fever
  • Skin issues (including raised bumps on the backs of arms, dry skin or dandruff)

The reality is however, anybody who is following a typical Western diet is most likely deficient in Omega- 3. Our fish and seafood intake is not usually sufficient to obtain adequate levels and falls considerably short on average, of the recommended two portions per week (one white and one oily). Even if you are meeting this guideline, the Scientific Advisory Committee acknowledges it as a modest recommendation in terms of Omega-3 as it factors in potential risks from contaminants (discussed here)1.

In addition to this, we are eating too many Omega-6 rich foods. Although Omega-6 is also integral to good health, some foods (such as vegetable oils and margarine) contain particularly high amounts. Evolutionarily speaking, our ratio between Omega-3 and Omega-6 is believed to have been roughly equal, although for those who eat a Western diet this is usually significantly out of proportion with at least 15 times (!) more Omega-6 than Omega-32 (you can see the table here if you would like to get an idea of your balance).

Getting your Omegas straight: the truth behind plant based sources

The three main types of Omega-3 in the human diet include: Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA) and Alpha-linolenic acid (ALA). Green leafy vegetables as well as some nut and seed oils (such as flax, linseed, hemp, chia, walnut) all provide ALA. What many people don’t realise however, is that it has been scientifically demonstrated that the health benefits related to Omega-3 fatty acids relate mostly to EPA and DHA. ALA needs to be converted to EPA and DHA in the body so as to become “active” and studies show us that this process is by no means efficient. On average, only 1–10% is converted into EPA and 0.5–5% is converted into DHA3,4.

Conversion equally depends on adequate levels of other nutrients, such as vitamins B3, B6, zinc, magnesium, manganese and vitamin A, which also tend to be lacking in the standard Western diet. Furthermore, omega-6 fatty acids compete for the same enzymes needed for the conversion process which can make it even more ineffective5.

Interestingly, research has revealed differences between men and women in the conversion of ALA, showing that women have a higher conversion than men. This is thought to be due to the importance of these fatty acids to the developing brain of a baby6.

Fishy fish sources? How to find the best

There are two main dilemmas when selecting fish or seafood for Omega-3s. One is contamination such as from heavy metals (as discussed in this post) and the other is sustainability.

You may think that you are making an ethical choice by choosing farmed fish, however, this also comes with its own set of problems. Excessive use of antibiotics, pesticides or the use of banned chemicals as well as excess nutrients from food and feces can have a negative impact on the flora and fauna of the ocean bottom. Fish farms also tend to be a breading ground for viruses and parasites which can pass to wild fish and present a risk to these populations7.

On top of this, the Omega-3 status of farmed fish is often not the same as wild varieties. As wild fish obtain their Omega-3 levels from the algae they consume, the differing diets of farmed fish can mean that they are less rich in Omega-3 fatty acids. Some popular farmed varieties such as Tilapia or Catfish have particularly poor profiles with a much higher Omega-6 to Omega-3 ratio8.

Good choices for both Omega-3 levels and from an environmental perspective can include a wild caught Alaskan salmon or otherwise fish low down on the food chain such as sardines or anchovies.  You can look for fish with the MSC logo which will ensure it has been sustainably sourced and the EDF site is an excellent resource with eco-friendly ratings as well as analyses on Omega-3 and mercury levels.

Supplements and how to choose them

ISSFAL (the International Society for the Study of Fatty Acids and Lipids), is an independent organisation that includes most of the world’s leading scientists in this area. They recommend a minimum intake of 500mg per day of EPA and DHA combined9 and other research suggests that up to 2000mg per day is a safe level to supplement at.

When you are choosing a supplement make sure to check how much EPA and DHA it actually contains. It may say it contains 1000mg of fish oil but the EPA and DHA levels will be lower than that.

There are three main types when choosing a fish oil:

  • Natural fish oil: This is the closest thing to eating real fish, with salmon, sardines and cod liver being the most common sources (again you can ensure it is certified by an official body such as the MSC or the Environmental Defence Fund for sustainability). This supplement contains oil in the form of triglycerides which has been shown to have better absorption than other forms10. As it is not concentrated, the levels of EPA and DHA will be lower, however, the other fatty acids it comes with as well as nutrients such as vitamin A and D can also improve absorption. Another benefit to natural fish oil is that it is more resistant to oxidation than processed oils11.
  • Processed fish oil: This oil has been purified and often concentrated. Advantages include that the purification process may have removed contaminants such as mercury from the oil and that it is likely to have a higher percentage of EPA and DHA. The downside however, is that the oil will be in ethyl ester form which is considerably less well absorbed12. This type of oil is also more prone to becoming rancid so be sure to break open a capsule and check for a foul smell every once in a while.
  • Reformed triglycerides: Some manufacturers process the oil even further to convert it back into a synthetic triglyceride form (it will say reformed or re-esterified triglycerides). This process is thought to improve absorption once again, however these will be the more expensive and less commonly available supplements.

If you are looking for a vegetarian or vegan option your best bet is probably a marine algae supplement such as algal oil. You might be pleased to hear that unlike green leafy vegetables and nut and seed oils, this does contain both EPA and DHA (remember the omega-3s in found fish originate from the algae). Although there is less research on this supplement in comparison with fish oil, the studies which have been done are promising. One study demonstrates that it has a positive effect on some of the risk factors for heart disease in vegetarians13 and another concludes it can be seen as nutritionally equivalent to cooked salmon14. Algal oil also comes with other benefits including being rich in important minerals such as iodine, being free from heavy metal contaminants and being much more environmentally friendly and sustainable.

Your body will thank you for it

Although it can feel like a minefield finding the best way to optimise your Omega-3s, informing yourself will enable you to make the best choice for you personally according to your preferences and beliefs, whether that is carefully selected fish or a high quality fish or algal oil supplement. It might make all the difference to your brain, eye and heart health.


  1. Scientific Advisory Committee on Nutrition (2004) Advice on Fish Consumption: Benefits and Risks. London, FSA
  2. Simopoulos, AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 2002 Oct;56(8):365-79.
  3. Gerster, H. Can adults adequately convert alpha-linolenic acid (18:3n-3) to eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)? Int J Vitam Nutr Res. 1998;68(3):159-73.
  4. Plourde M, Cunnane SC. Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements.Appl Physiol Nutr Metab. 2007 Aug;32(4):619-34.
  5. Gerster, H. Can adults adequately convert alpha-linolenic acid (18:3n-3) to eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)? Int J Vitam Nutr Res. 1998;68(3):159-73
  6. Burdge GC, Wootton SA. Conversion of alpha-linolenic acid to eicosapentaenoic, docosapentaenoic and docosahexaenoic acids in young women. Br J Nutr. 2002 Oct;88(4):411-20.
  7. World Wildlife Fund:
  8. K.L.Weaver et al. “The Content of Favorable and Unfavorable Polyunsaturated Fatty Acids Found in Commonly Eaten Fish,” J Am Diet Assoc. 2008 Oct;108(10):1785
  9. ISSFAL.Recommendations for Dietary Intake of Polyunsaturated Fatty Acids in Healthy Adults, June 2004
  10. Neubronner J et al. Enhanced increase of omega-3 index in response to long-term n-3 fatty acid supplementation from triacylglycerides versus ethyl esters.Eur J Clin Nutr. 2011 Feb;65(2):247-54. doi: 10.1038/ejcn.2010.239. Epub 2010 Nov 10.
  11. Sullivan Ritter, J.C., Budge, S.M., Jovica, F. et al. Oxidation Rates of Triacylglycerol and Ethyl Ester Fish Oils. J Am Oil Chem Soc (2015) 92: 561. doi:10.1007/s11746-015-2612-9
  12. Sullivan Ritter, J.C., Budge, S.M., Jovica, F. et al. Oxidation Rates of Triacylglycerol and Ethyl Ester Fish Oils. J Am Oil Chem Soc (2015) 92: 561. doi:10.1007/s11746-015-2612-9
  13. Conquer JA & Holub BJ. Supplementation with an algae source of docosahexaenoic acid increases (n-3) fatty acid status and alters selected risk factors for heart disease in vegetarian subjects. J Nutr 1996;126:3032-3039.
  14. Arterburn LM, et al. Algal-oil capsules and cooked salmon: nutritionally equivalent sources of docosahexaenoic acid. J Am Diet Assoc 2008;108:1204-1209.
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