Omega-3s in Vegetarian Diets

The article I wrote, Omega-3’s: Are You Getting Enough?, for the Made Just Right blog had to be removed due to legal concerns regarding giving health advice, so I am reprinting it here. And I added a short section on children towards the end.

Summary

There is strong evidence that omega-3 fatty acids are useful in the prevention and treatment of heart disease. There is also some evidence that they might be important for cognitive function or useful as a treatment for depression. While short-chain fatty acids are found in a variety of plant and animal foods, fish provide the main source of the long-chain omega-3s. There are also long-chain omega-3 vegan supplements made from seaweed. Especially in the case of older vegetarians, there is a concern that an omega-3 deficiency could cause cognitive problems and omega-3 supplementation is recommended.

Background on Omega-3s

There are three important omega-3 fatty acids:

1. α-linolenic acid (ALA) is a short chain fatty acid. It is found in small amounts in animal flesh, in very small amounts in a variety of plant products, and in relatively large amounts in soy, walnuts, canola oil, camelina oil, and in flax, hemp, and chia seeds and their oils. The human body cannot make its own ALA, it is an essential fatty acid that must be obtained through the diet.

2. Eicosapentaenoic acid (EPA) is a long chain fatty acid. It is found in large amounts in fatty fish, in small amounts in eggs, and in very small amounts in seaweed. Some EPA is converted into other molecules that can reduce blood clotting, inflammation, blood pressure, and cholesterol.

3. Docosahexaenoic acid (DHA) is a long chain fatty acid. Like EPA, it is found in large amounts in fatty fish, in small amounts in eggs, and in very small amounts in seaweed. It is a major component of the gray matter of the brain, and also found in the retina, testis, sperm, and cell membranes.

All three of these omega-3 fatty acids may prevent heart arrhythmias, though ALA has been studied the least in clinical trials.

The body can convert ALA into EPA, and EPA into DHA. ALA is efficiently converted to EPA, but it may require large amounts of ALA to produce optimal amounts of DHA.

Health Benefits

The American Heart Association (AHA) recommends that adults eat at least two servings of fatty fish a week. The AHA says that people with coronary artery disease may want to talk to their doctor about fish oil supplements, and, especially for people with high triglycerides, large doses of fish oil could help.

An ALA intake of about 2 g/day has been consistently associated with a modest lowering of heart disease risk.

There is evidence that EPA and/or DHA supplementation may improve depression and cognition, particularly in infants, children and older adults, although the results of clinical trials have been mixed.

Vegetarians and Omega-3 Status

Vegetarians, including vegans, have been shown in many studies to have lower levels of EPA and DHA than meat eaters. We do not know if lower blood DHA levels reflect lower levels in other tissues in vegetarians, though it is a reasonable assumption.

Because EPA reduces blood clotting, one way to figure out if vegetarians are getting enough EPA is to compare the blood clotting parameters of vegetarians to omnivores. Two studies have done this and found the differences to be minimal.

Vegetarians already have about a 24% lower risk of heart disease than regular meat-eaters and on average have lower triglyceride levels, and it is not clear that EPA or DHA supplementation will further reduce their risk.

In terms of depression and cognition, there has been no research on omega-3s and vegetarians, but Joel Fuhrman, MD, has a private practice seeing many long-term vegans and has observed some older vegan men with very low DHA levels and cognitive problems, so there is reason to be prudent regarding DHA in older vegans, especially men.

Improving Omega-3 Status in Vegetarians

The traditional way that vegetarians were encouraged to raise EPA and DHA levels was by increasing ALA and decreasing linoleic acid (LA), a short chain omega-6 fatty acid. Although the body can convert ALA into EPA, the enzymes that do this also convert LA into longer chain omega-6s. If there is too much LA in the diet, the enzymes can be saturated with LA and unable to convert omega-3s. An ideal ratio of omega-6 to omega-3 in the diet is thought be about 3 or 4. Vegans tend to have a ratio of 10 to 15 compared to a ratio of 6 to 10 for omnivores.

To deal with this problem, in the late 90s and 00s, vegetarian health professionals recommended increasing ALA intake and decreasing LA intake. Unfortunately, there are no long-term studies looking at the EPA and DHA levels in vegetarians who follow these recommendations. Research shows that 3 – 4 g of ALA per day per day can increase DHA levels; assuming intake of omega-6 is low.

Increasing ALA to 3 – 4 g/day has some concerns. Three studies looking at age-related eye damage and fatty acids, all coming from the Nurse’s Health Study, have associated modest ALA intakes with age-related eye problems. The ALA in these studies came mostly from animal products that were likely cooked (omega-3s are easily oxidized by heating). It is not clear that the association is causal or if the causation would apply to uncooked ALA (i.e., from plants).

Although ALA has been associated with prostate cancer risk in some studies, the association has been shown with a fair degree of certainty not to be causal.

If it weren’t for the (small chance) for potential eye problems, my recommendations would be either to add 3 g of ALA per day or to take a DHA supplement. Because of the chance for eye damage, that much ALA is not worth the risk when DHA supplements are available and more effective. Vegetarians should still add .5 g of ALA per day for its benefits on heart disease and to help increase EPA levels. Such small amounts of uncooked ALA should pose no risk to the eyes.

Recommendations

Following all three of these recommendations should keep vegans on par with fish eaters:

1. Take a DHA Supplement

Under 60 years old: 200 – 300 mg every 2-3 days
60+ years old: 200 – 300 mg per day

2. Do not prepare food with oils high in omega-6 such as corn, soy, safflower, sunflower, most vegetable oil blends (typically labeled “vegetable oil”) and sesame oil. Instead, use low omega-6 oils like olive, avocado, peanut, or canola.

3. On average, vegetarians meet about 50 to 60% of the daily ALA recommendations without special diet planning and should add 0.5 g of uncooked ALA daily. This would be the equivalent of:

1/5 oz *English walnuts (3 halves)
1/4 tsp of flaxseed oil
1 tsp of canola oil
1 tsp ground flaxseeds

*English walnuts are the typical walnuts for sale in grocery stores. They are distinct from black walnuts.

Too much omega-3 can result in bleeding and bruising. If you have reason to believe you have problems with easy bleeding or bruising consult a health professional before increasing your omega-3 intake.

Vegan DHA & EPA Supplements

There are now many companies offering vegan DHA supplements made from seaweed. Some of them include EPA. Some DHA can be converted into EPA and if you are supplementing your diet with .5 g of ALA, you probably do not need a DHA supplement that also contains EPA, but there’s no harm from doing so.

Vegetarian Children and DHA

There is a concern that dietary DHA may be important to developing fetuses and infants. Anthropologist John H. Langdon argues that DHA is not an essential nutrient for the brain development of infants. Pregnant women efficiently convert ALA to DHA and fetuses and infants are able to receive DHA that is released from the mother’s fat tissues and provided through the umbilical cord or breast milk. Langdon argues that in cases of very low maternal levels of DHA, infants can utilize other fatty acids for brain tissue that can later be replaced by DHA.

In a study comparing breast milk, cow’s milk formula with DHA, soy formula with DHA, and soy formula without DHA, infants who ate soy formula without DHA had indications of slower parasympathetic development, though still within the normal range.

A 1994 study measured the DHA levels in the umbilical cords of 32 infants born to vegetarian mothers compared to omnivores, and revealed no relationship between DHA and the birth weight or head circumference of the infants.

Many children have been raised vegan without supplementing with DHA, or even extra ALA, and appear to develop well. Despite this, parents of vegetarian children are encouraged to supplement their diets with DHA at 200 mg every two or three days until more is known about DHA in vegan infants.

Flax & Chia Facts

Flax

• Flaxseeds are the most concentrated source of alpha-linolenic acid (ALA), with an omega-6 to omega-3 ratio of 1:4.

• One teaspoon of flaxseed oil contains 2.5 g of ALA.

• One tablespoon of ground flaxseeds contains 1.6 g of ALA.

• If flaxseeds are not ground, they will not be digested. They can be ground in a blender or coffee grinder, and then stored in the freezer. Ground flaxseeds can be sprinkled on cereal or used in baked goods.

• Cooking flaxseed oil damages the ALA, but it can be put on warm food such as toast. Flaxseed oil should be kept in the refrigerator.

• A straight teaspoon of flaxseed oil does not taste so great. Some people use cinnamon-flavored oil, tablets, or put it on toast or salad to make it taste better.

Chia

• Chia (Salvia hispanica; also known as Salba) seed oil is a good source of ALA.

• Dried chia seeds have 5 g of ALA per ounce, although their omega-6 to omega-3 ratio of 3:1 is not nearly as good as flax.

More Information

This article is an abridged version of Omega-3 Fatty Acid Recommendations for Vegetarians which is fully annotated.

In addition to a short article I’ve written, Fish and Cardiovascular Disease, The Linus Pauling Institute at Oregon State University provides an in-depth review of omega-3s and heart disease in Essential Fatty Acids.

27 Responses to “Omega-3s in Vegetarian Diets”

  1. Jessica @Vegbooks Says:

    This is very helpful information — thank you!

    Do you have recommendations of sources of DHA for children? My daughter resists taking the Dr. Fuhrman DHA drops I bought her, even mixed with juice (which is a rare treat). I am able to sneak ground flax and flax oil into her diet, but as you note, these are sources of ALA, which the body must convert to DHA. Any advice you can provide would be greatly appreciated.

  2. Jack Norris RD Says:

    Jessica,

    I don’t know of any DHA for children. I don’t have kids so I have no experience in what might get them to eat something. I would just try using smaller amounts and putting into food that will make it less distinguishable.

  3. gull Says:

    Hello Jack,

    Just wanted to say that I am very happy to find your blog, so I can learn more about vegan nutrition! Thanks for profetional advices!

  4. Tamara Says:

    Thanks for the reminder Jack! You inspired me this morning to take one of the vegan DHA capsules that have been sitting in my cabinet for a while… but it gives me really gross fishy burps – yuck! (yeah, I know, it’s seaweed, not fish, but it tastes fishy and disgusting to me) … no way around that, I guess. I’d also like to get this supplement into my 6-year-old son every few days but he can’t swallow a big pill like that – I guess I could cut one open and pour the contents into a smoothie though? Maybe that would help for me as well; I’ll have to give it a try… take care.

  5. Jessica @Vegbooks Says:

    Good point! I was thinking of liquids, but now that you mention food, I realize that perhaps I could sneak the DHA drops in a no-heat dessert, such as a chocolate mousse pie (from tofu) or a chia pudding. Wouldn’t hurt the adults to get a little extra too!

  6. Jack Norris RD Says:

    Jessica,

    If you mix it into a hot dessert after you’ve cooked it and it’s cooled off a bit, it should be okay.

  7. Jack Norris RD Says:

    Tamara,

    > to take one of the vegan DHA capsules that have been sitting in my cabinet for a while…it tastes fishy and disgusting to me

    If you are keeping your DHA in a cabinet and you’ve had it for a couple months, there’s a good chance it has gone rancid and that’s why it is so distasteful. You should keep it in the refrigerator and use it up relatively quickly. I really don’t know how long it takes to go bad in the fridge but I’m thinking more than 6 months is probably too long.

  8. Jacob Dijkstra, M.D. Says:

    Do you know the content of lignans (phyto-estrogens) in chia seeds? According to Dutch researchers, flax seeds have an extremely high content of these phyto-estrogens (301,129 microgram/100 g fresh edible weight; for comparison, peanuts contain only 94 ug/100 g). I emailed one of the companies that sells chia seeds, but they actually did not know the phyto-estrogen content. They indicated that they would research this issue.

  9. Jack Norris RD Says:

    > Do you know the content of lignans (phyto-estrogens) in chia seeds?

    I don’t. Since I only recommend a small amount of extra ALA, an amount that can be gotten through 3 walnut halves, I don’t worry too much about the sources of ALA and all the side issues that come along with them.

  10. dysomniak Says:

    Hi Jack, thanks for the article and thanks in general for providing evidence based info on vegan health.

    I’m wondering what you think of the claims made by the frozen waffles (I’ll name the brand if you like but you can probably guess) I buy to contain 1 gram of ALA per serving. If ALA from flax won’t survive cooking then how can these waffles (admitedly tasty) actually deliver? Can any prepared food be trusted to deliver it’s advertised omega 3s?

    Not that it’s a real issue for me personally: I don’t mind taking DHA and I don’t even need a health reason to enjoy my little handful of walnuts every day.

  11. Jack Norris RD Says:

    dysomniak,

    I’m not sure how evidence-based this response is going to be, but my understanding is that baking cracked flax seeds it not terribly damaging to the flaxseed oil. In other words, the seed contains substances that protect the fats from the dry heat. Other types of heating are worse for oil, and if the oil isn’t in the seed at all, then it isn’t protected. And if the seed isn’t cracked, then you won’t digest it. So, lots of variables, but that’s what I’ve read about them – I haven’t seen actual studies looking at the fat degradation of baked, cracked flaxseeds, though.

    > Can any prepared food be trusted to deliver it’s advertised omega 3s?

    As you are hinting, it might be best to make sure you’re getting a more direct source. Walnuts work well!

  12. Diane Says:

    I mail-ordered a vegetarian DHA supplement. Unfortunately, it spent two days in a black, metal mailbox with a high in the mid-90s. I am assuming such heat has rendered the product useless/rancid. Your thoughts?

  13. Jack Norris RD Says:

    Diane,
    I’d call the company and ask them.

  14. Nadine Says:

    Hi!

    I would like to know if microalgae containing omeg-3s also contain cobalamin analogues.

    Thank you.

  15. Jack Norris RD Says:

    Nadine,

    If you mean the supplements, then no – they would be separated from the final preparation.

  16. Joe Says:

    Jack,

    Thank you for this information. I have some questions about the following section of your article: “If it weren’t for the (small chance) for potential eye problems, my recommendations would be either to add 3 g of ALA per day or to take a DHA supplement. Because of the chance for eye damage, that much ALA is not worth the risk when DHA supplements are available and more effective. Vegetarians should still add .5 g of ALA per day for its benefits on heart disease and to help increase EPA levels. Such small amounts of uncooked ALA should pose no risk to the eyes.” Before getting to the questions, some background may be helpful.

    On the NutritionFacts.org website, Dr. Michael Greger recommends two tablespoons of flaxseeds a day (see the video at http://nutritionfacts.org/video/just-the-flax-maam/ and his comment near the bottom of that page). (In a separate comment though, he suggests not going over 4 tablespoons/day.) Per your article, two tablespoons of ground flaxseeds would contain 3.2 grams of ALA.

    Also on that website, Dr. Greger posted a blog and video series discussing how eating “a handful or two” of nuts a day may not cause significant weight gain, and therefore seems to suggest that there’s no major adverse risk from doing so (see e.g. http://nutritionfacts.org/2012/12/27/nuts-dont-cause-expected-weight-gain/). He says that a “handful” in this context “typically refers to an ounce. So that’s like 23 almonds, 14 walnut halves, or 21 filberts (hazelnuts)” (http://nutritionfacts.org/questions/what-is-the-definition-of-a-handful-of-nuts/). So per the above and your article, a handful of walnuts would contain about 2 1/3 grams of ALA, and two handfuls would contain about 4 2/3 grams of ALA.

    Based on Dr. Greger’s recommendations (and before I read your article), I recently started eating two tablespoons of ground flaxseeds and about a handful of walnuts a day. That appears to translate to about 5.5 grams of ALA a day. At some point I also began taking a daily Nuique omega-3 supplement (http://www.nuique.com/omega3/) containing 200 mg DHA and 50 mg EPA. (I believe your full annotated version of this article has a dead link to a different formulation of this supplement called “V-Pure”.)

    After reading your article, I am concerned that the ALA content of the flaxseeds and walnuts might cause or exacerbate problems with my eyes. I already have very advanced near-sightedness and astigmatism in both eyes, and I’m only 33. My eyes also seem to be perpetually dry and I’ve been prescribed eye drops by several eye doctors to try to treat the condition. So I take any eye risks pretty seriously, even if it is a relatively small risk. I’m perfectly willing to drop or scale back the flaxseeds and walnuts consumption if it might reduce eye problem risks.

    My questions are:

    -Do you recommend reducing flaxseed, walnut and all other plant-based ALA sources to below 3 grams of ALA a day?

    -If so, what is the maximum safe amount of the ALA-rich plant foods in your view?

    -Are you aware of any circumstances under which it should be safe to consume 3 or more grams of plant-based ALA a day?

    Thank you.

  17. Jack Norris RD Says:

    Joe,

    My honest opinion is that ALA at the levels found in those studies were not the cause of the eye problems. That said, I do not have any proof for that view, other than my own incredulity, and I do not want to dismiss the findings of a team of researchers, many of whom are more familiar with the issue than I am.

    That said, the amounts of ALA associated with eye problems in those studies were much lower than 3 g per day – they were about half that, adding to the concern with 3 g per day or more.

    -Do you recommend reducing flaxseed, walnut and all other plant-based ALA sources to below 3 grams of ALA a day?

    I do not have recommendations regarding this. My concern is that I don’t actively recommend something that could harm people and that is why I recommend DHA supplements rather than high intakes of ALA. But I would not recommend against flaxseeds or walnuts as the data on eyesight is too preliminary. Walnuts have many benefits and I wouldn’t want someone to miss out on them based on this preliminary info on ALA and eyesight.

    Since you are especially worried about your eyesight, then taking a DHA supplement and eating plenty of almonds is probably the way to go for peace of mind if nothing else.

  18. Joe Says:

    Jack,

    Thank you for your response. Focusing on flaxseeds for the moment, Dr. Greger’s pretty clear that he recommends everyone take two tablespoons of ground flaxseeds daily to get the full benefit of this food. It seems like the benefits of flax may be relatively unique to this food, so if you choose not to eat flax or the amount he recommends, it might be hard to get all the same benefits from other foods. But as you seem to be pointing out, just one tablespoon of flaxseeds might theoretically have a risky amount of ALA. On the other hand, your past blog posts about Dr. Greger’s videos suggest that you generally like them. And as you said, the risk of having too much ALA is based on preliminary info. So based on that, it would be great to know: Do you choose to personally include two tablespoons of flax in your meals every day, even if you might not necessarily generally recommend this?

    Thanks,

    Joe

  19. Jack Norris RD Says:

    Joe,

    In Dr. Greger’s Optimum Nutrition Recommendations for vegans, he does not recommend flaxseeds, but rather a DHA supplement. I personally do not eat flaxseeds but that is due to the fact that my blood clots a tiny bit too slowly and I don’t want to add anything that might make it clot even more slowly.

    I tend to want a great deal of evidence before I would recommend a particular food because it is critical for preventing cancer or living longer. I’m sure that if Dr. G says flaxseeds are good, there is good evidence that they are, but I wouldn’t get too stressed out if, for some reason, you don’t want to risk eating them every day.

  20. Andrea Says:

    http://www.sciencedirect.com/science/article/pii/S0003986101923616
    http://www.sciencedirect.com/science/article/pii/S0952327802002673
    http://en.wikipedia.org/wiki/File:EFA_to_Eicosanoids.svg

    According to the biochemical science, it is more efficient eating raw leafy greens(they include ALA and are high in Vitamin A) to raise EPA/DHA levels on a vegan diet than solely eating more ALA rich/Vitamin A deficienct foods.

  21. Kelly Says:

    What do you think of this from the PCRM website?

    Women following vegan diets have significantly more omega-3 “good fats” in their blood, compared with fish-eaters, meat-eaters, and ovo-lacto vegetarians, according to a new report from the European Prospective Investigation into Cancer and Nutrition (EPIC) Study. Levels in vegan men were not quite as high as in vegan women. Despite zero intake of long-chain omega-3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and substantially lower intake of their plant-derived precursor alpha-linolenic acid (ALA), vegan participants converted robust amounts of shorter-chain fatty acids into these long-chain fatty acids. The study included 14,422 men and women aged 39 to 78.

    Welch AA, Shakya-Shrestha S, Lentjes MAH, Wareham NJ, Khaw KT. 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 a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. Am J Clin Nutr. 2010;92:1040-1051.

  22. Jack Norris RD Says:

    Kelly,

    That was a very misleading study. I briefly address it in this post:

    http://jacknorrisrd.com/dha-supplements-a-good-idea-especially-for-older-vegan-men/

  23. m Says:

    I think it would be good to address if the high fiber in flax prevents absorption of supplements such as calcium & B12 when taken at the same meal
    Thanks

  24. Jack Norris RD Says:

    m,

    I’m not aware of the fiber reducing B12 absorption or calcium to any significant degree.

  25. m Says:

    Thanks for your speedy reply=)
    Are there any concerns with rancidity when taking a DHA & EPA supplements made of seaweed oil,wouldn’t the veggie gel capsule mask a bit of the odour?Obviously it is best to use any product Before Before date…

    I’m taking a 200mg DHA and 6mg EPA from Helhetshälsa its the only one I can find where I live.Ingredients:
    Algal oil (Schizochytrium sp.), Sunflower oil, antioxidants (ascorbyl palmitate,
    tocopherols, rosemary extract), sunflower lecithin.
    Vegetable capsule made of: modified corn starch, firming
    (glycerin, sorbitol), water, thickener (carrageenan), color (beta-carotene, caramel).
    The thing is I suffer from both severe depression and borderline personality disorder(BPD) and high doses of EPA have been shown to help BPD symptom in a few studies s,so I’m wondering if I should be taking 2capsules per day/more…with food?
    Lastly I’m wondering if by soaking walnuts to make them more digestible,when you throw out the water with the tannins… do you lose some of the omega 3or help the absorption by soaking.
    Thanks!

  26. Jack Norris RD Says:

    m,

    I’m sorry to hear you suffer from depression and BPD. I am not qualified to recommend how much you should supplement for those issues. You should talk to a physician.

    As for your other questions, if you keep the DHA/EPA supplement refrigerated and use before the expiration date, the rancidity should be minimized.

    I am not aware that soaking walnuts would result in their losing any omega-3s. I doubt it, but I’ve never seen research on it.

  27. m Says:

    Sadly no physician/psychiatrist/nutritionist I’ve been to seems to know much other than the studies published which I have already read.Thanks anyway

Leave a Reply

*