Let’s face it, trying to follow a healthy and balanced diet can be hard sometimes and you can easily get lost in the details. The fact that you are reading this post, tells me that you are on the search to get more knowledge about omega-6 and omega-3 fatty acids on a vegan diet and how they influence your health. Maybe you have read some articles before mentioning an optimal omega-6 to omega-3 ratio to decrease inflammation or that you should try to limit your consumption of foods that contain omega-6 fatty acids since they will cause inflammation in your body. So, with all this information out there, it can be easy to fall into a trap that I like to call “Micromanaging Your Diet”.
Let me give you a short example: Nuts generally contain more omega-6 than omega-3 so to minimize inflammation you should avoid them, right? But here is the catch. You only look at one nutrient and the effect this nutrient could have on your body. If you try to do this for every single nutrient you will go crazy. In fact, nuts are related to a number of health benefits.
The following post goes into detail and talks a lot about percentages and values, but don’t get lost here. Use this information and knowledge to make practical adjustments in your diet but don’t overcomplicate things. Life is too short to plan your diet into the smallest detail. Furthermore, if you are not interested in the details you can just skip to the practical guidelines on the bottom of this post, even though I would recommend that you don’t.
What are essential fatty acids (EFAs)? EFAs cannot be synthesized by the body and have to be obtained from food. You have certainly heard before that omega-6 and omega-3 fatty acids are important in human nutrition. These short-chain fatty acids obtained through your diet are converted by the body to longer-chain fatty acids for further use.
Being on a vegan or vegetarian diet the long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are of high importance. EPA and DHA are mainly found in fatty fish and are therefore a topic of debate in plant-based nutrition. Since they can be synthesized from short-chain n-3 fatty acids, which are found in a lot of plant sources, there is potential to meet the daily requirements without supplementation. However, this synthesis is said to be only limited. In this post we will discuss the following topics:
- What are fats?
- What are the EFAs and their derivatives?
- How much of the EFAs do we need?
- How efficient is the synthesis of EPA and DHA from short-chain omega-3 fatty acids?
- Which factors inhibit or facilitate this synthesis?
What are fats?
Fats provide 9 kcal per gram which make them an important dietary fuel source. Besides providing energy they are needed to facilitate the absorption and transportation of fat-soluble vitamins, insulate body organs, maintain body temperature and are an important factor for cell functioning.
- Saturated fatty acids (SFA): If the fatty acid has all the hydrogen atoms it can hold it is said to be saturated.
- Monounsaturated fatty acids (MUFA): If some of the hydrogen atoms have been replaced by a double bond between the carbon atoms, then the fatty acid is said to be unsaturated. If the fatty acid has one double bond as highlighted by the green arrow below, then the fatty acid is monounsaturated.
- Polyunsaturated fatty acids (PUFA): If there is more than one double bond pointed out by the green arrows below, then the fatty acid is described as polyunsaturated. The positioning of the double bonds determines its type, with the two main types being omega-3 and omega-6 fatty acids.
The body can make the fatty acids it needs except for two, known as alpha-linolenic acid (omega-3) and linoleic acid (omega-6).
The EFAs and their derivatives
Alpha-linolenic acid (ALA) and linoleic acid (LA) must be ingested from food and are called essential fatty acids. From these two 18-carbon essential fatty acids our body can synthesize long-chain (20-and 22-carbon) fatty acids which are important for overall health.
- Linoleic acid (n-6) is mainly converted to the 20-carbon arachidonic acid (AA)
- Alpha-linolenic acid (n-3) is mainly converted to the 20-carbon eicosapentaenoic acid (EPA) and 22-carbon docosahexaenoic acid (DHA)
EPA and DHA can also be obtained pre-formed through the diet and are mainly found in fish and seaweed. ALA, on the other hand, is found in plant-based foods, such as flax seeds, hemp seeds, and walnuts.
Functions of omega fatty acids
The EFAs and the fatty acids synthesized from them are important components of cell membranes and precursors to important signaling molecules.
EPA and AA are necessary to build these signaling molecules, which are called eicosanoids. Eicosanoids play a vital role in many physiological systems. They work like hormones, but in contrast to hormones do not like to travel. That’s why they are also referred to as “local hormones”. In the context of this post, in particular, we will take a look at the role of eicosanoids in inflammation and immune response.
DHA, on the other hand, is the most abundant omega-3 fatty acid in the brain and forms an essential part of neural membranes. Studies indicate that DHA aids in the production of nervous system cells facilitates the brain signaling process and protects against oxidative stress, which slows down brain degeneration.
How much of the EFAs do we need?
The European Food Safety Authority (EFSA) has the following recommendations:
|in % of total energy||in g / mg|
|Omega-3 (ALA)||1%||2 – 3g|
|Omega-6 (LA)||4%||8 – 12g|
|EPA and DHA||0.1%||250mg|
The EFSA recommends that 1% of total energy intake should come from Omega-3 fatty acids and 4% from Omega-6 fatty acids. Therefore, if your daily calorie needs are 2,500 kcal, the recommended amounts for Omega-3 fatty acids would be around 2.8g (25 kcal) and for Omega-6 fatty acids around 11g (100 kcal). Of course, you don’t have to follow these recommendations up to the decimal, but you can use them as a general guideline.
Side note: There is one common exception to the above-stated recommendations. In pregnant and breastfeeding women there is an additional demand for EPA and DHA since these long-chain omega-3 fatty acids are required for the normal development of the child’s brain and visual system. Recommended are an additional 400 to 550 mg of EPA and DHA, of which about 200 – 300 mg should be DHA.
These guidelines are established for a standard western diet, which includes fish as a direct source of EPA and DHA. If we have to rely on the conversion process of ALA to EPA and DHA from plant foods, we will most probably require more ALA as mentioned above.
EFA Conversion Process
EPA and DHA are mainly found in marine sources like fish and algae. Other plant-based sources only contain the short-chain omega-3 fatty acid ALA which has to be converted to EPA and DHA. Since EPA and DHA cannot be found in plant foods, vegans have to rely on the conversion of omega-3s, if they are not supplementing EPA and DHA.
To get a better understanding of the conversion process of the short-chain omega-3 and omega-6 fatty acids to their long-chain derivatives, namely EPA, DHA, and AA as well as the eicosanoids I have created the following graph.
Figure 1 – Conversion Process
As you can see there are basically 4 total steps involved. Marked in green you can see the omega-3 fatty acids and derivatives. The omega-6 fatty acids are marked in blue. The orange funnels are the enzymes that function as catalysts for the conversion, namely delta 6 desaturase (Δ6D) and delta 5 desaturase (Δ5D). Before we start I would like to show you how the chemical structure is noted, for you to be able to get the most out this.
An 18-carbon ALA has three double bonds; therefore, the structure is noted as the following: ALA (18:3). If you add a double bond (desaturation) the notation would change to 18:4, if you now add a carbon atom (elongation) the notation would change to 19:4. The ones that are highlighted in bold are the important fatty acids on which we will focus later on. So, know that we got the basics covered, let’s break down the process:
1. In step 1, the short-chain omega fatty acids ALA (18:3) and LA (18:2) are first desaturated by adding an additional double bond via the Δ6D enzyme and then further elongated to 20-carbon fatty acids by elongase enzymes. The results are ETA (20:4) and DGLA (20:3) which are then used for further conversion.
2. Step 2 is similar to the previous step. The Δ5D enzyme adds another double bond ETA and DGLA leading to EPA (20:5) and AA (20:4).
3a. In this step, the long-chain omega fatty acids EPA and AA are converted to their eicosanoid derivatives.
3b. EPA is not only used to create eicosanoids but also further converted through elongation by adding another two carbon atoms to form DPA (22:5).
4. As you can see, the Δ6D enzyme is then used again to create another double bond leading finally to DHA (22:6). DHA is then used to form part of neural cell membranes and to produce further eicosanoids.
Ratio between omega-6 and omega-3
The most important points from the conversion process above are that the omega-3 and omega-6 fatty acids use the same enzyme system for conversion and that Δ6D is used twice for creating DHA.
As you might have already guessed, the ratio between omega-6 and omega-3 fatty acids plays an important role in nutrition. Since both LA and ALA use the same enzymes for the conversion process, they compete against each other for the conversion to their long-chain derivatives. This means that the more of any one of these EFAs is consumed, the higher the concentration of their long-chain derivatives will be.
- Increasing the ratio of LA will lead to an increased concentration of AA. Omega-6 fatty acids will inhibit the enzymes for the omega-3 fatty acids to be converted into EPA and DHA. Additionally, a high concentration of LA also inhibits incorporation of DHA and EPA into tissues.
- Increasing the ratio of ALA will lead to an increased concentration of EPA and DHA since it will free up the enzymes for the omega-3s.
Please note that we are talking about the ratio here and not about increasing absolute amounts. We will see later on in this post, why this is so important. Furthermore, what I have just explained is still a topic of debate and I have found some contradicting studies to this view as well. 
Benefits of a balanced ratio
As we have seen before, the derivatives of these two conversion systems are further used to produce similar substances, such as e.g. eicosanoids and DHA. Eicosanoids are important factors in the inflammatory process, blood clotting, and blood pressure regulation. The eicosanoids from omega-6 and omega-3 fatty acids have mostly opposing effects on the above-mentioned factors.
|Eicosanoids from omega-6||Eicosanoids from omega-3|
|generally promote inflammation||generally less inflammatory,|
or even anti-inflammatory
|increase blood clotting||prevents blood clotting|
|promote constriction of arteries||promote dilation of arteries|
This doesn’t mean that one can be labeled as good and the other as bad. Inflammation itself is necessary to protect the body from infection or injury. We need pro-inflammatory eicosanoids that drive the inflammatory process, as well as equally powerful anti-inflammatory eicosanoids that reverse the inflammatory process. A certain balance of pro-inflammatory and anti-inflammatory eicosanoids is therefore essential.
Too little of an inflammatory response and the body is unable to repel microbial invasions or heal injuries. Too much of an inflammatory response and the immune system begins attacking the body’s own organs eventually leading to chronic disease.
However, if this balance is shifting to either side, adverse health effects could occur. In our standard Western diet, this balance typically shifts more to the omega-6 fatty acids, with the omega-6 to omega-3 ratio usually being above 10:1, often as high as 20:1 or 30:1. The effects of this high ratio can be observed in figure 2.
Figure 2 – Eicosanoid production
As mentioned before, the higher the ratio of omega-6 fatty acids, the higher the concentration of AA will be. Subsequently, more pro-inflammatory eicosanoids will be produced, since enzymes will mostly be blocked for the omega-3s. This creates a pro-inflammatory state and makes the body more susceptible to allergic and inflammatory disorders such as e.g. cardiovascular disease and type II diabetes.
Balancing the ratio can bring the following health benefits:
- Prevention of coronary heart disease
- Suppression of pro-inflammatory compounds (which has an influence on inflammatory conditions such as arthritis, diabetes, inflammatory bowel disease, cancer, and aging)
- Positive impact on brain functioning and the central nervous system2
- Better visual and neurocognitive development of the child in pregnant women
Optimal omega-6 to omega-3 ratio
Currently, most of us are far away from an optimal ratio. But what guideline can we use to reach a ratio that is beneficial for our health?
In the time where there were no processed oils and foods, such as the hunter-gatherer age, the omega-6 to omega-3 ratio was roughly 1:1. This ratio is described by most as the optimal ratio since it provides the right balance of omega-6 to omega-3. Though it is not impossible to achieve this ratio nowadays, it is still a lot harder with the abundance of processed oils found in most foods. The good news is that most studies suggest that to reduce inflammatory disease anything between a ratio 2-4:1 ratio should already be a good reference.
Factors inhibiting or facilitating the conversion
There are certain factors that can inhibit or facilitate the conversion process which you have to keep in mind if you are following a plant-based diet.
Relative ratio of omega-6 to omega-3 fatty acids
As we have seen before, the relative ratio has a great effect on the conversion. Consuming too much omega-6 in the form of LA will inhibit the conversion of omega-3 fatty acids. Try to keep your ratio below 4:1.
Absolute amounts of omega-6 and omega-3
I have mentioned earlier that not only the relative ratio plays an important role but also the absolute amounts of both ALA and LA. As we have seen in figure 1, the Δ6D enzyme is used twice in the conversion of ALA to DHA. Δ6D has a higher affinity for ALA and LA than for DPA, the precursor of DHA. This means, that increasing the absolute amounts of both ALA and LA can have an adverse effect on DHA synthesis.
A quick example: if you are currently consuming a 20:1 ratio you shouldn’t increase the amount of ALA by adding more flaxseeds or hemp seeds to your diet. The excess ALA together with the LA you were already consuming will inhibit the DPA that will be waiting for conversion by the Δ6D enzyme. It would be smarter to lower your absolute amounts of LA ingested to decrease the ratio. To optimize conversion to DHA the following two studies suggest an overall intake of 5-6% of PUFA in total dietary requirements, which would translate roughly to 10 – 20 g. 
EPA and DHA conversion seems to be more effective in women than in men. What is even more interesting, is that women have the ability to up-regulate the conversion during pregnancy. This ensures that the DHA needs of the fetus are met. This capacity for adaptation is of particular importance in vegan pregnancies, where a direct dietary provision of DHA is absent, and in multiple and sequential pregnancies, where demand for DHA will be much greater than usual. 
No direct source of EPA and DHA
Studies found that the conversion rate is greater for non-fish-eaters compared to fish-eaters. This suggests that vegans are better at converting ALA to EPA and DHA since they are not consuming the long-chain omega-3s directly.19 Another great example of the adaptational mechanisms the body is capable of.
Efficiency of the conversion process
We now know that conversion of ALA to EPA and DHA is possible. What we have to keep in mind, however, is that the conversion rate is only around 5 – 9% for EPA and around 0.1 – 4% for DHA, which means an overall rate of 5 – 13%. The efficiency of the conversion furthermore depends on the individual because the capacities to convert short-chain to long-chain omega fatty acids can differ from person to person and also depends on the factors mentioned above.  However, if we consider a worst-case scenario, with a conversion rate of 5% you would have to consume around 5 g of ALA to end up with around 250 mg of EPA and DHA, which should be sufficient for our body.
To underline this: Studies of vegetarians and vegans, in which DHA derived from ALA is the sole source of DHA, show that DHA levels are generally 0 – 40% lower than those of omnivores. On the other hand, neurological disease rates are comparable to omnivores which suggests that ALA-derived DHA is sufficient to maintain brain function.
Another study mentions that the conversion process in healthy individuals consuming a balanced diet may be sufficient to maintain tissue function.
With all these numbers and percentages mentioned, what is a practical guideline we can follow without micromanaging our diet to the smallest detail?
I have created a short list of principles to make it easier to keep the omega-6 to omega-3 ratio at a balanced level, without having to plan everything out in further depth. Most of these principles should be part of a healthy diet anyway, so chances are that you are already following them.
Eat whole foods and try to limit the amount of processed foods
I think it is obvious to say that whole foods are much healthier and more nutrient-packed than processed foods. Keep in mind that a lot of processed foods contain cheap and refined vegetable oils which are high in omega-6 fatty acids and for that reason throw your ratio out of balance. This doesn’t mean cutting out whole food omega-6 sources such as nuts and seeds, though.
Cut out or limit vegetable oils including margarine
Try to cut out or limit your consumption of vegetable oils such as soybean oil, corn oil, canola oil, sunflower oil etc. This goes hand in hand with the first recommendation.
Eat plant foods high in omega-3 fatty acids
To keep a balanced ratio, try to include foods that are high in ALA such as flaxseeds, hemp seeds, chia seeds, walnuts. Although beans are not as high in ALA, they still provide good amounts and usually have a good ratio. To reach the 5 g mentioned earlier it would be enough to consume one tablespoon of flaxseeds and chia seeds with a few walnuts.
If you would like to learn more about omega-3 rich plant foods, I have dedicated an own blog post to this topic. listing the most important vegan sources for omega-3 fatty acids.
As we have seen, people following a plant-based diet, do not have to rely on ingesting EPA and DHA directly from food. They can rather focus on the conversion process from ALA to EPA and DHA, although the conversion rate is not really optimal. By leading a diet which limits processed foods and vegetable oils and is rich in whole foods and good sources of ALA such as flax seeds or chia seeds, healthy individuals should be able to rely on the conversion process to meet EPA and DHA needs.
However, if you want to be on the safe side or you are in a special situation where you have an increased demand for long-chain omega-3 fatty acids, especially DHA, such as e.g., during pregnancy and lactation, then you might want to consider taking an algae oil. Algae is the only plant food that contains EPA and DHA, and also the source where fish gets their EPA and DHA from.
 European Food Safety Authority (EFSA). (2009). Labelling reference intake values for n‐3 and n‐6 polyunsaturated fatty acids. EFSA Journal, 7(7), 1176.
 Greenberg, J. A., Bell, S. J., & Van Ausdal, W. (2008). Omega-3 fatty acid supplementation during pregnancy. Reviews in obstetrics and Gynecology, 1(4), 162.
 Gibson, R. A., Muhlhausler, B., & Makrides, M. (2011). Conversion of linoleic acid and alpha‐linolenic acid to long‐chain polyunsaturated fatty acids (LCPUFAs), with a focus on pregnancy, lactation and the first 2 years of life. Maternal & child nutrition, 7, 17-26.
 Su, H., Liu, R., Chang, M., Huang, J., & Wang, X. (2017). Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Food & function, 8(9), 3091-3103.
 Johnson, G. H., & Fritsche, K. (2012). Effect of dietary linoleic acid on markers of inflammation in healthy persons: a systematic review of randomized controlled trials. Journal of the Academy of Nutrition and Dietetics, 112(7), 1029-1041.
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 Limbu, R., Cottrell, G. S., & McNeish, A. J. (2018). Characterisation of the vasodilation effects of DHA and EPA, n-3 PUFAs (fish oils), in rat aorta and mesenteric resistance arteries. PloS one, 13(2), e0192484.
 Simopoulos, A. P. (2016). An increase in the omega-6/omega-3 fatty acid ratio increases the risk for obesity. Nutrients, 8(3), 128.
 Simopoulos, A. P. (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & pharmacotherapy, 56(8), 365-379.
 Portolesi, R., Powell, B. C., & Gibson, R. A. (2007). Competition between 24: 5n-3 and ALA for Δ6 desaturase may limit the accumulation of DHA in HepG2 cell membranes. Journal of lipid research, 48(7), 1592-1598.
 Welch, A. A., Shakya-Shrestha, S., Lentjes, M. A., Wareham, N. J., & Khaw, K. T. (2010). Dietary intake and status of n–3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of α-linolenic acid to long-chain n–3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort–. The American journal of clinical nutrition, 92(5), 1040-1051.
 Gerster, H. (1998). Can adults adequately convert a-linolenic acid (18: 3n-3) to eicosapentaenoic acid (20: 5n-3) and docosahexaenoic acid (22: 6n-3)?. International Journal for Vitamin and Nutrition Research, 68(3), 159-173.
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