Published on 03/01/2018

What is Omega-3?

In general, fats have a bad reputation, so it’s important to remember that not all fat is bad!
There are three different types of fatty acids: saturated, monounsaturated, and polyunsaturated fatty acids. Polyunsaturated fatty acids are comprised of the omega-6 and omega-3 families, have received a lot of attention in recent years because they are considered “good” fats.
Our bodies can’t make these fats due to a lack of the appropriate enzymes, but they are necessary for the maintenance of good health and have a role in brain function, mood balance and even the development of the eyes and brain in children, so we must get them through food. Omega-6 and omega-3 fatty acids are therefore collectively referred to as essential fatty acids1,2.
What foods are omega-6 fatty acids found in?
The principal omega-6 fatty acid is called linoleic acid, and it is found in vegetable oils, such as corn, safflower, sesame, soybean, and sunflower oils1. Gamma-linolenic acid (GLA) is another omega-6 fatty acid that can be found in a wide variety of foods, notably small amounts are found in organ meats1. It is also found in the plant seed oils of evening primrose, blackcurrant, and borage oils. Finally, dietary arachidonic acid (AA) comes primarily through the consumption of eggs and animal fats1.
What foods are omega-3 fatty acids found in?
Alpha-linolenic acid (ALA) is found in green leafy vegetables, seaweed, and some nuts and seeds2. Some of the top food sources of ALA include flax, chia, and hemp. ALA is also found to a lesser extent in some vegetable oils2.
The other type of omega-3 fatty acids in our diet are referred to as long-chain polyunsaturated fatty acids2. This includes eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which come from marine-based sources, like fish and algae. It is the omega-3 fatty acids EPA and DHA that confer many of the health benefits commonly associated with omega-32.
Are all omega-3 fatty acids the same?
The challenge is that while people may consume sources of omega-3 ALA mentioned above (such as from flax and vegetables), many don’t consume fish or algae on a regular basis. Therefore, EPA and DHA are consumed at much lower levels. EPA and DHA are generally absent from plant food sources rich in ALA3.  While the body can  convert ALA to EPA and DHA, humans are not very efficient at  performing this conversion, converting <5% of consumed ALA to EPA + DHA4. This is important because although flax for example may contain a high amount of omega-3 fatty acids by weight, based on those researched estimates <5% of the ALA is converted to EPA and DHA4. Therefore, consuming direct sources of EPA and DHA is a more efficient way to  increase  these long chain polyunsaturated fatty acid levels within the body than simply consuming high levels of ALA. The most direct way of providing EPA and DHA for the body is through the consumption of fish or algal oils.



  1. Higdon, J et al., 2003. Essential Fatty Acids. [online] Linus Pauling Institute. Available at: <> [Accessed 5 October 2021].
  2. 2021. Office of Dietary Supplements - Omega-3 Fatty Acids. [online] Available at: <> [Accessed 5 October 2021].
  3. Harris WS. Omega-3 fatty acids. In: Coates PM, Betz JM, Blackman MR, et al., eds. Encyclopedia of Dietary Supplements. 2nd ed. London and New York: Informa Healthcare; 2010:577-86.
  4. Plourde, M. and S.C. Cunnane, Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements. Appl Physiol Nutr Metab, 2007. 32(4): p. 619-34.