We need fat to enable our body to function. It’s an essential macronutrient that we need to get from the foods we eat. In this blog were going to look at what the essential fatty acids are, what that means, their function, and sources of them.
When we talk about a nutrient being essential it means that we cannot synthesise it (make it ourselves) in our body, and therefore we must obtain it from what we eat and drink. These nutrients enable our body to function efficiently and maintain our health.
There are two types of essential fatty acids: Omega 3 (alpha-linolenic acid) and omega 6 (linoleic acid). Both linolenic acid and linoleic acid are the simplest form of each of their respective groups. These are both polyunsaturated fatty acids (PUFAs).
There are 3 types of fats and the difference between these is in their hydrocarbon chain (hydrogen and carbon) and the bond between the carbons:
So, let’s look at both omega 3 and omega 6.
Different Types of Omega 3
There are three types of omega-3 fatty acids. The shortest chain alpha-linolenic acid (ALA), can be converted into longer chain omega 3 fatty acids which are called eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found within plant oils, and EPA and DHA can be obtained within marine oils such as oily fish.
Foods Containing Omega 3
As mentioned above, oily fish, including tuna, salmon, and herring are sources of EPA and DHA omega 3s and other sources of these are eggs, krill oil, and algae. Sources of EPA and DHA are mainly derived from animals.
Sources of ALA come from plants including; walnuts, chia seeds, flaxseeds, hemp seeds, green leafy veg, soya beans, and sacha inchi (an oil which is balanced in its essential fatty acids).
Granola with Yoghurt and Walnuts
Our body isn’t as efficient at converting ALA into the long chain EPA and DHA - most of the research into potential health benefits indicates these two chains, so it is important to look at including oily fish when possible. However, we know that due to dietary lifestyle choices this isn’t always possible. When following a vegetarian or vegan diet, you should try to ensure that you have a daily intake of ALA, and to reach the recommendations that would be a daily intake of: 1 tablespoon of chia seeds or ground linseeds, 2 tablespoons of hemp seeds, or 6 walnut halves (The Vegan Society, 2017). It is also possible to supplement with EPA and DHA from micro algae as well.
Functions of Omega 3
Lots of studies have found relationships between health benefits related to the longer chain omega 3s (DHA and EPA) rather than short chain ALA.
EPA and DHA play a role in being anti-inflammatory, whereby they in turn reduce the level of inflammation within our cell membrane when inflammation levels may be high.
It has been found that middle-aged and elderly women who had a higher intake of omega 3s, also had a healthier diverse microbiome, regardless of how much fibre they were consuming. They also had different types of bacteria that help to produce anti-inflammatory compounds. It is important to remember that intake of omega 3 is correlated with a healthier lifestyle generally. The study concluded that supplementing with omega 3’s alongside prebiotic and probiotic supplementation can help with microbiome composition and diversity (Menni et al., 2017). Having a healthy gut is an important thing to look at, and you can read more about it here. We also have a blog which discusses our microbiome and probiotics here.
It has been found that when pregnant women supplemented with fish-oils at 22 weeks until their baby was delivered, it lead to an improvement in the foetal omega 3 levels, and also prevented depletion of the mother’s own storage (Krauss-Etschmann et al., 2007).
When looking at the subject of depression, a meta-analysis looked at whether EPA and DHA showed clinical benefits in relation to depressive symptoms. It was found that when EPA was used as a supplementation, there was significant clinical benefits with symptoms than those individuals who were on placebos (Hallahan et al., 2016). However, even though this study does show some positives, it is not without its limitations and so cannot be seen as the only answer when looking at depression. It is also believed that efficient intake of omega 3 whilst pregnant helps to decrease immune responses in children, and this includes a decrease in the number of allergies (Swanson et al., 2012). It is believed that a higher intake of omega 3’s, especially those from fish, may help in reductions of some chronic diseases which are involved with inflammation, this includes cardiovascular disease, inflammatory bowel disease and arthritis (Wall et al., 2010).
Even though they are both polyunsaturated fatty acids, they have different structures and functions. As we’ve seen, omega 3’s functions are involved in reducing cellular inflammation, and we will now look at omega 6, which is involved in cell inflammation.
Different Types of Omega 6
Similar to omega 3, linoleic acid is the short chain fatty acid for omega 6, and it can be made into a longer chain omega 6 fatty acid, called arachidonic acid.
Foods Containing Omega 6
Foods which contain omega 6 include:
Functions of Omega 6
Omega 6 such as arachidonic acid (AA), is used in cell membranes and is an important precursor for eicosanoids - these are lipid mediators that play an important role in lots of biological processes, two of which are inflammation and immune function (*Department of Health, 2012. Calder, PC. 2006). Inflammation is something that we need to help protect our body. It can be used as a defence mechanism, helping to protects us from infections and factors which may cause ill health, helping to repair tissues, and also balancing infected or damaged areas (Calder, 2010). Overall it is protective, and helps to rid tissues of injury (Serhan et al., 2009). When controlled properly, regulation of inflammation in the body allows us to remain healthy.
It is suggested that we should be consuming a diet where we have a ratio of omega 6 to omega 3 of 1:1. So that means that we should be consuming equal amounts of omega 3 to omega 6. However, that does not appear to be the case especially with the Western diet. In many cases, it has been found that we tend to eat a much higher ratio of omega 6 to omega 3. It has been estimated that those in the western world are consuming a ratio of omega 6:omega 3 which ranges either 20:1 to 15:1 and in many cases, some even put this estimate higher (Simopoulos, 2002. Simopoulos, 2016). In the UK it has previously been found that men are getting 1% and women 1.1% of their average daily intake of omega 3, whereas both men and women have an average intake of 5.1% for omega 6s (British Nutrition Foundation, 2017).
Is there an issue if we do not have a balanced ratio?
Well, getting the balance between the two is important. When we consume a diet which is high in linoleic acid, it may lead to the body being unable to convert as much ALA into EPA and DHA, reducing the amount of these omega 3’s in the blood, and therefore reducing them being able to carry out their functions (Vegan Society, 2017). This is due to ALA and linoleic acid competing with each other, and omega 6 is more successful in being converted. This imbalance, whereby there is more omega 6 in our diet, is proinflammatory and prothrombotic, and this could potentially increase our risk of obesity, diabetes, and atherosclerosis (Simopoulos, 2016). However, when we have a balanced ratio of omega 3 and omega 6, and there is an equal conversion, the EPA can cause a reduction in the amount of AA you produce.
You may have heard of a third omega, called omega 9, however I haven’t discussed this here as it is not essential, and we can synthesise it in our body.
It is important to make sure that we get a correct balance of omegas. This may mean increasing our level of omega 3 where possible and is the reason why we’re advised to eat 2 portions of fish a week, including one oily fish.
Daisy Buckingham ANutr Registered Associate Nutritionist
British Nutrition Foundation. (2017). Fat: fat in the diet. Available here.
Calder, PC. (2010). Omega-3 fatty acids and inflammatory processes. Nutrients. Available here.
*Department of Health. (2012). Manual of Nutrition 12th Edition. London:TSO.
Hallahan, B. Ryan, T. Hibbeln, JR. Murray, IT. Glynn, S. Ramsden, CE. SanGiovanni, JP. And Davis, JM. (2016). Efficacy of omega-3 highly unsaturated fatty acids in the treatment of depression. The British Journal of Psychiatry. Available here.
Menni, C. Zierer, J. Pallister, T. Jackson, MA. Long, T. Mohney, RP. Steves, CJ. Spector, TD. Valdes, AM. (2017). Omega-3 fatty acids correlate with gut microbiome diversity and production of N-carbamylglutamate in middle aged and elderly women. Scientific Reports, 7(11079). Available here.
Krauss-Etschmann, S. Shadid, R. Campoy, C. Hoster, E. Demmelmair, H. Jiménez, M. Gil, A. Rivero, M. Veszprémi, B. Desci, T. and Koletzko, BV. Effects of fish-oil and folate supplementation of pregnant women on maternal and fetal plasma concentrations of docosahexaenoic acid and eicosapentaenoic acid: a European randomized multicentre trial. American Society for Clinical Nutrition. Available here.
Serhan, CN. Yacoubian, S. and Yang, R. (2009). Anti-inflammatory and pro-resolving lipid mediators. Annual Review of Pathology. Available here.
Simopoulos, AP. (2002). The importance of the ratio of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & Pharmacotherapy. Available here.
Simopoulos, AP. (2016). An increase in the omega-6/omega-3 fatty acid ratio increases the risk for obesity. Nutrients. Available here.
Swanson, D. Black, R. Mousa, SA. Omega-3 fatty acids EPA ad DHA: health benefits throughout life. Advances in Nutrition; An International Review Journal. Available here.
The Vegan Society. (2017). Omega-3 and omega-6 fats. Available here.
Wall, R. Ross, RP. Fitzgerald, GF. and Stanton, C. (2010). Fatty acids from fish: the anti-inflammatory potential of long-chain omega-3 fatty acids. Nutrition Reviews. Available here.
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Daisy has a Master's Degree in Public Health Nutrition, which is Association for Nutrition (AFN) accredited. She, also, has a BSc degree in Psychology and Cognitive Neuroscience; and has completed an AFN accredited Diet Specialist Nutrition course. She is Lucy's sister and is the Lucy Bee voice on all aspects of nutrition and its effect on the body. In addition to this, Daisy is shadowing a nutritionist in Harley Street and working for an NHS funded project, The Diabetes Prevention Programme.