The Essential Fatty Acids
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 we're going to look at what the essential fatty acids are, what that means, their function, and sources of them.
A Background to ‘What are the Essential Fatty Acids?’
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:
- saturated fatty acids - each carbon on the chain is attached to 2 hydrogens, and each is connected via a single bond
- monounsaturated fatty acids - the chain has 2 hydrogens missing, the carbons form a single bond along the chain
- PUFAs - 2 or more double bonds on their hydrocarbon chain, which means that 2 or more hydrogen atoms are missing from the chain. These fats will remain liquid, even when they are refrigerated (unlike olive oil, and as you’ve probably realised, coconut oil). They keep our cells’ wells in a healthy condition and allow them to work effectively. They also have a role within cholesterol in transporting, excreting and breaking it down.
So, let’s look at both omega 3 and omega 6.
Omega 3
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 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.
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: 1/2 tablespoon of our sacha inchi oil; 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 3s 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.
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 an 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 3s, 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).
The Difference Between Omega 3 and Omega 6
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.
Omega 6
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:
- hemp seeds
- pumpkin seeds
- sunflower seeds
- soybeans
- walnuts
- some animal fats
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.
What is the Correct Ratio of Omega 6 to Omega 3?
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?
As long as you are getting enough omega 3 you don’t need to worry about the ratio of the two realistically, especially if you are consuming a healthy, balanced diet.
Although omega 6 may have protective inflammatory effects, both omega 3 and omega 6 downstream have anti-inflammatory protective effects. The reason that people are aware of omega 6 is that it is a precursor for arachidonic acid, which is a signalling molecule for being proinflammatory, which is where there is a fear that excess omega 6 may be an issue. However, it has been studied that higher intakes of omega 6 doesn’t impact the amount of arachidonic acid, in studies where omega 6 was reduced by over 90% or increased by up to a 6-fold, plasma arachidonic acid was not affected.
In theory it would make sense that excess omega 6 would lead to excessive inflammation but studies seem to point towards the fact that our body is able to adapt and convert what it needs of the omega 6 into its precursors.
When looking at omega 3 and omega 6, it is a lot more complicated than just omega 3 being anti-inflammatory, and omega 6 being proinflammatory, as mentioned above, another study looked at the relationship between omega 6 and coronary heart disease, however, no association was found, and higher levels of arachidonic acid were actually associated with lower risks for coronary heart disease events. It’s not only arachidonic acid which omega 6 is turned into, but also protective and anti-inflammatory.
There is some concern that omega 6 may impact or slow omega 3 ALA conversion in EPA and DHA, and instead only focus on converting omega 6 into arachidonic acid. However, as study by Liou et al., found that when omega 6 intake was increased for energy intake that it did reduce EPA levels slightly, but also increased DHA levels the same amount that EPA decreased by (-0.4 for EPA, and +0,4 for DHA). Meaning that total EPA and DHA were not affected. This has been confirmed by Goyens et al., whereby increased omega 6 intake does reduce conversion on ALA into EPA, but increased the absolute amount of DHA synthesised. Low omega 6 diets, and those high in omega 3 ALA does increase the amount of EPA synthesised, however it does not, or has been found to only slightly change DHA plasma levels. One thing that is important is to ensure that you are getting enough ALA in your diet (or if you consume fish, including 2 portions of fish a week with 1 portion a week being oily fish to get your omega 3). In a lot of cases you’ll find people consume high amounts of omega 6, but not enough omega 3, which is where some issues can arise, which is why it’s important to make sure that you are including a source of omega 3, most plant-based sources of omega 3 do in fact contain omega 6 as well. It may be more important to potentially focus on the individual amounts of omega 3 and omega 6, instead of being concerned over the ratio. Although a decrease in omega 6 may increase ALA to EPA in plasma, however, it appears to actually impact the amount of DHA we are able to synthesise.
So, although there is some sense in the fact that omega 6 may impact omega 3 conversion, it has also been found that high levels of omega 6 are not proinflammatory in the sense that they can cause coronary heart disease, they do have an inflammatory role in the body, but we do need this to an extent. The topic of omega 3 and omega 6 is complicated and as with all things nutrition. It’s always important to think about the diet as a whole, and excessive omega 6 won’t increase inflammation, but other factors can play a huge role in excessive/chronic inflammation is not directly caused by omega 6, but also overall diet, stress, lack of sleep, smoking, excessive alcohol intake, and lack of physical activity. Making sure that we are getting enough omega 3 is what we should be aware of, the ideal ratio is a concept however the true ideal ratio has not actually been identified, so ensuring enough omega 3 is being consumed is more important than focusing on omega 6 intake. Looking at a ratio does not distinguish those that are getting enough of omega 3 and 6, and those who consume little to none.
Omega 9
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.
Conclusion
It is important to make sure that we get enough omega 3 in our diet. 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 portion oily fish, or if you are vegetarian or vegan, ensuring you are getting enough omega 3 ALA which you can read more about here.
All of our recipes can be found here.
Daisy, MSc PGDip ANutr, is a Registered Associate Nutritionist with a Master's Degree in Public Health Nutrition, and a Post Graduate Diploma in Eating Disorders and Clinical Nutrition, both of which are 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.
Daisy has worked for an NHS funded project, the Diabetes Prevention Programme; and shadowed a nutritionist in Harley Street.
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References:
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.
Goyens, PLL., Spilker, ME., Zock, PL., Katan, MB., and Mensink, RP. 2006. Conversion of a-linolenic acid in humans is influenced by the absolute amounts of a-linolenic acid and linoleic acid in the diet and not by their ratio. The american Journal of Clinical Nutrition, Available here.
Liou, YA., King, DJ., Zibrik, D., and Innis, decreasing linoleic aid with constant a-linolenic acid in dietary fats increases (n-3) eicosapentaenoic acid in plasma phospholipids in healthy men. The Journal of Nutrition. 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.
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.
