My intern Zachary Wenger has previously written about whether protein, certain vitamins or minerals are of concern for those adopting a vegan diet. To wrap this series up, this article explores whether or not omega-3 fatty acids are a concern for vegans. 

What Are Omega-3 Fatty Acids?

Omega-3 fatty acids play vital roles in the synthesis of cellular membranes and are found abundantly in the eyes and brain. They are also important for fetal development and heart health. 

There are three main forms of omega-3 fatty acids:

• Alpha-linolenic acid (ALA)
• Eicosapentaenoic acid (EPA)
• Docosahexaenoic acid (DHA) 

ALA is considered an essential fatty acid, as our bodies are unable to create it by itself, therefore, we need to obtain it from our diet. 

EPA and DHA can technically be produced in the body by converting a small portion of ALA (when ALA is consumed in the diet). However, this conversion of ALA into DHA and EPA isn’t a very efficient process, especially in relation to producing DHA. For example, healthy people have been found to have a conversion rate of ALA to EPA and DHA of only about 5-8% — although conversion rates may vary based on other factors, like the amount of omega-6 in your diet (1).

Overall, the best way of increasing omega-3 levels in the body is by consuming EPA and DHA from food or dietary supplements. 

ALA is found in:

• Certain plant oils like flax, hemp, and walnut oil
• Flax seeds
• Chia seeds
• Hemp seeds
• Walnuts
• Soya-based foods

EPA and DHA are found in:

• Oily fish like salmon, mackerel, herring, kippers and sardines
• Shellfish
• Seaweed and algae
• Omega-3 fortified products e.g. fortified eggs and dairy

What About Plant-Based Sources of Omega-3?

Although there are plenty of plant-based sources of ALA (as listed above), seaweed and algae are the only plant-based sources of DHA and EPA and these foods come with some additional considerations.

For example, a study published in 2011 tested seven seaweed species from the North Sea and examined their fatty acid content (2). None of the strands, except one, contained DHA (sargassum natans). Interestingly, all of the different strands that were tested contained a small amount of EPA. While that sounds exciting, to put this into perspective, an average serving of seaweed from the grocery store contains 5g of seaweed. If we were to select the highest containing EPA seaweed from the study (palmaria palmata) and compare that to a serving of cooked salmon, the EPA content wouldn’t even come close — with roughly 0.04 grams of EPA in the 5g serving of seaweed versus 0.59 grams of EPA in an 85g serving of cooked salmon.

The cooked salmon contained nearly 15 times more EPA than the seaweed, and this was the highest EPA-containing seaweed from the study so it would be much lower for other strands. 

There are also issues with consuming a high amount of seaweed. This is primarily due to the iodine content of seaweed. As discussed in our previous blog post, “Are Vegan Diets Low in Certain Minerals” iodine is an essential nutrient. However, in excess, it can adversely affect thyroid function and can negatively affect pregnancy. The tolerable upper limit for iodine is 1,100 mcg per day and the iodine content of seaweed has been found to vary from 16 mcg to 2,984 mcg per gram, with brown seaweed like kelp usually containing the highest amount (3-4). 

What About Omega-3 Supplements For Vegans?

Algae oil supplementation seems to be a potential workaround for vegans. With the limited amount of trials that are published to date, algae oil has been found to significantly raise DHA levels, which did not occur with walnut, flax, or echium seed oil (5).

In a 2008 paper, 600 mg of DHA from algae oil raised DHA levels significantly more than the same amount of DHA from salmon (6).

It should be noted that this was just a two-week trial containing just over a dozen participants in each group. The takeaway from this study is that DHA from algae oil may raise DHA levels similarly to animal sources of DHA. 

Pregnant vegans often benefit from taking an EPA/DHA supplement, as DHA status is found to be lower in the breast milk of vegan/vegetarian mothers than omnivorous mothers (7-8). This is a vital nutrient for the health and development of their baby (9).

The American Pregnancy Association recommends that pregnant women take a daily supplement of at least 300 mg of DHA (10). This recommendation should be of extra importance to vegans. 

There is an established link between consuming enough omega-3 fatty acids and heart health. However, a recent Cochrane review concluded that “moderate‐and high‐quality evidence suggests that increasing EPA and DHA has little or no effect on mortality or cardiovascular health (11).” Interestingly, when looking through the tables and forest plots, there were indeed beneficial and significant findings. For example, when multiple trials were pooled together, there was a 7% reduction in overall coronary heart disease events when comparing high EPA/DHA intake as compared with low intakes. The 7% reduction in risk was statistically significant and clinically relevant, as it could save a substantial amount of lives. Keep in mind though, none of the trials included used algae oil. 

To date, there is one published trial in relation to algae oil and cardiovascular health.

In a small study with vegan participants, 0.2g supplementation of DHA per day for 3 months had no effect on arterial stiffness relative to a placebo (12). That’s all that we have. Ideally, it would be better to have a study investigating actual cardiovascular disease risk in DHA supplemented vegans to non-supplemented vegans, rather than just arterial stiffness.

Take Home Messages

The best data that we have to date is that algae oil can increase DHA levels similarly to salmon. It may also raise EPA relative to a placebo.

Note: if algae oil is something that sounds intriguing, make sure to choose a brand that supplies enough EPA and DHA. Certain algae oil brands don’t contain EPA. 

We don’t currently have any published data on how algae oil directly affects cardiovascular risk.

However, algal oil supplements are often advised that vegans take algae oil as a precautionary measure. One situation where omega-3 supplementation for vegans is especially important is during pregnancy, where a supplement which contains at least 300mg of DHA per day is recommended. 

As always, please consult a qualified health professional for individual advice if you are unsure about whether you should be taking an omega-3 supplement. 

Check out this article for more information about omega-3 fatty acids.

References

1. Burns-Whitmore, Bonny et al. “Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration?.” Nutrients vol. 11,10 2365. 4 Oct. 2019, doi:10.3390/nu11102365
2. Van Ginneken, Vincent J T et al. “Polyunsaturated fatty acids in various macroalgal species from North Atlantic and tropical seas.” Lipids in health and disease vol. 10 104. 22 Jun. 2011, doi:10.1186/1476-511X-10-104
3. Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington (DC): National Academies Press (US); 2001. 8, Iodine. Available from: https://www.ncbi.nlm.nih.gov/books/NBK222323/
4. Teas J, Pino S, Critchley A, Braverman LE. “Variability of iodine content in common commercially available edible seaweeds”. Thyroid. 2004 Oct;14(10):836-841.
5. Lane, Katie et al. “Bioavailability and potential uses of vegetarian sources of omega-3 fatty acids: a review of the literature.” Critical reviews in food science and nutrition vol. 54,5 (2014): 572-9. doi:10.1080/10408398.2011.596292 
6. Arterburn, Linda M et al. “Algal-oil capsules and cooked salmon: nutritionally equivalent sources of docosahexaenoic acid.” Journal of the American Dietetic Association vol. 108,7 (2008): 1204-9. doi:10.1016/j.jada.2008.04.020
7. Sanders, Thomas A B. “DHA status of vegetarians.” Prostaglandins, leukotrienes, and essential fatty acids vol. 81,2-3 (2009): 137-41. doi:10.1016/j.plefa.2009.05.013
8. Sanders, T A, and S Reddy. “The influence of a vegetarian diet on the fatty acid composition of human milk and the essential fatty acid status of the infant.” The Journal of pediatrics vol. 120,4 Pt 2 (1992): S71-7. doi:10.1016/s0022-3476(05)81239-9
9. Burdge, Graham C et al. “Long-chain n-3 PUFA in vegetarian women: a metabolic perspective.” Journal of nutritional science vol. 6 e58. 23 Nov. 2017, doi:10.1017/jns.2017.62
10. “Omega 3 Fatty Acids: FAQs.” American Pregnancy Association, 24 June 2020, americanpregnancy.org/pregnancy-health/omega-3-fatty-acids-faqs/
11. Abdelhamid, Asmaa S et al. “Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.” The Cochrane database of systematic reviews vol. 7,7 CD003177. 18 Jul. 2018, doi:10.1002/14651858.CD003177.pub3
12. Sanders, Thomas A B. “Plant compared with marine n-3 fatty acid effects on cardiovascular risk factors and outcomes: what is the verdict?.” The American journal of clinical nutrition vol. 100 Suppl 1 (2014): 453S-8S. doi:10.3945/ajcn.113.071555
13. Geppert, Julia et al. “Microalgal docosahexaenoic acid decreases plasma triacylglycerol in normolipidaemic vegetarians: a randomised trial.” The British journal of nutrition vol. 95,4 (2006): 779-86. doi:10.1079/bjn20051720
14. Hu Y, Hu FB, Manson JE. Marine omega-3 supplementation and cardiovascular disease: an updated meta-analysis of 13 randomized controlled trials involving 127,477 participants.J Am Heart Assoc. 2019; 8:e013543.