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Wednesday, June 09, 2010

Best sources of DHA omega-3 essential fatty acid

Axolotl by Ethan Hein from flickr (CC-NC-SA)

This is surprisingly difficult to find out, so I decided to share the results with everyone. But first, background:
  • Animals need omega-3 and omega-6 essential fatty acids
  • The same enzymes are used for omega-3 and omega-6 processing, so too much of one will interfere with the other. People used to have diets with about 1:1 omega-3:omega-6. Today ratio is more like 1:20, and that little omega-3 we eat is mostly ALA.
  • Three most important omega-3 are ALA (18 carbons), EPA (20 carbons), and DHA (22 carbons).
  • Brains are made largely out of DHA.
  • Land plants produce no EPA / DHA. None whatsoever. Zero.
  • Some land plants produce adequate amounts of ALA, but even this is uncommon.
  • Algae produce quite a lot of EPA / DHA.
  • Animals including humans can convert ALA to EPA, and then DHA, but this is a painfully slow and inefficient process; and over-saturation of omega-6 and many conditions interfere with even that much.
Based on this some people believe it would be wise to try to increase amount of omega-3 fatty acids in diets. Hard evidence is rather lacking, this is however to be expected as hard evidence of anything about diet is essentially nil. It's almost only short term studies of crappy proxies, and there are millions of reasons why this is just wrong. Anyway, concerning supplementation:
  • All mixed omega-3/omega-6/omega-9 supplements are waste of money - you're eating too much omega-6 already, and you can make as much omega-9 as you wish yourself.
  • You don't want generic "omega-3" supplements - most of these are ALA, which is of very limited use. You want DHA. At worst EPA. ALA is little more than filler, it's not bad for you but it's less relevant, and much easier to get via normal diet anyway.
  • If you're surprised why it's so hard to get DHA, this is possibly highly relevant.
Hopefully now you see why I'm measuring DHA, not anything else. And to keep science proper what I'm interested in is "% of calories coming from DHA", not "grams of DHA per portion" or anything like it. Portions are whatever manufacturer says they are, "per 100g" measures mostly tell you how much water foods have, and only "% of calories from" measures the right thing.

Escher Symmetry by Pieter Musterd from flickr (CC-NC-ND)

Best Sources of DHA


I digged through USDA National Nutrient Database, and this is what I found.
  • The data only contains "food" not supplement pills and such. These will of course contain highest concentrations. Rarely eaten foods like dolphin meat are not in the database, so I have no idea how nutritious dolphin sashimi would be.
  • The best source of DHA is unsurprisingly - fish oil. Salmon oil is 18.2% DHA and 34.2% omega-3 altogether; other fish oils are pretty good too, but not so much. Other oils like cod liver, sardine, and menhaden are 8.5%-10.9% DHA, 18.8%-26.6% total omega-3. Herring oil is less impressive 4.2%/11.1%. Fish oil also contains most mercury and other poisoning, so enjoy that. Once ultra-refined you won't need to worry about poisoning but it's more supplementation than food.
  • The second best source is caviar/roe, with 7.7%-13.6% DHA, and 13.7%-24.2% total omega-3. Might be expensive to turn it into a major part of your diet.
  • The third best source is seal oil with 6.5-12% DHA, 14.0-27.7% omega-3. Let's see if you can buy some legally outside Canada. So far we're totally out of luck.
  • Finally something more useful. The fourth best source is salmon. There's wide range of nutritious value from 2%/4% to 8.9%/13.7% - depending on where they're caught and what's their diet. Fortunately there doesn't seem to be a big difference between wild and farmed salmon, so either will work. Unfortunately the same mercury poisoning problem applies as to fish oil - poisonous substances are stored in oil so the oilier (and more useful for us) the fish the more toxic, and there is no way to escape that.
  • Fifth best source is mackerel. Like salmon, it can have as little as 1.5%/2.8% or as much as 8.7%/14.7%.
USDA says the next best source is dried parsley leaves at 7.3%/9.9% - which is most likely a massive measurement error, as there are no other plants anywhere, and it really makes little sense.

Old friend by JennyHuang from flickr (CC-BY)


Other than that, it's fish, fish, fish, mollusks, jellyfish, crustaceans, and more fish. My hopes for finding something that's not fish are getting slimmer and slimmer, so I'm just going to skip all of them now (you can probably see the pattern), and only focus on things which are not fish/seafood.
  • Brains. Beef/lamb/pork brains have 3%-5.4% DHA and 4.4%-7.7% total omega-3. Not surprisingly, as that's what animals primary need DHA for. And we simply throw away this most nutritious part.
  • Whale oil - 3.9%/8.3%. Whale meat on the other hand is pretty useless at 0.2%/0.5%. Not that you'll find much of either at the nearest supermarket. It's technically not a fish. Anyway, between brains and ocean creatures we pretty much ran out of good sources, the next source is:
  • Roasted squirrel - and that at mere 0.5%/0.6%
  • Chicken can be anywhere from 0.1%/0.2% to 0.5%/0.8%
  • Egg yolk - 0.3%-0.4% DHA, 0.4%-0.7% total.
  • Whole egg - 0.2%-0.3% DHA, 0.2%-0.8% total. Pretty much all of that in yolk.
  • We're long past useful concentrations anyway, so I won't be listing them. Next on the list are caribou, green turtles, turkeys, lamb kidneys, frog legs, guineahen, lamb hearts, squab/pigeon, pork livers, bear, raccoon, pork lung (and other beef/lamb/pork offal), and emu. Pork/beef/lamb meat doesn't register other than as rounding error.
So to summarize:
  • Get supplements;
  • Or eat a lot of fish and other seafood;
  • Or eat ridiculous amount of poultry, eggs, and game meat;
  • Or you're fucked.
There's no way to get enough DHA in anything resembling standard Western diet. Simply no way. Fruits and vegetables contain none, even "organic" ones. Actually fast food contains more as it often uses eggs and poultry as ingredients, but that's still not that useful.

One more long-term option would be to genetically engineer some common oily plants like soy or canola to produce some EPA/DHA - even if humans wouldn't eat them, if they're used as animal feed, we'd benefit indirectly quite a lot.

Actually someone already genetically engineered pigs to produce 4x omega-3 fatty acids, including 2x DHA, which sounds like the most urgent reminder that we need GMO now, and Luddites should not be in charge of policy.

EDIT: GM soybeans with more omega-3 (this most likely means ALA) and higher stability so they don't need partial hydrogenation has just been approved in US. If people moved from usual partially hydrogenated soybean oil to that it would be a massive health benefit. Of course our Euro-Luddites + CAP-paid farmer lobby coalition will probably ban it until long after "America vs Europe" picture get reversed. It's already much closer than you think.

13 comments:

Quickshot said...

Hmm, you looked in to it a bit more in depth then I have. But I can see it didn't change the ultimate conclusions by all to much. On a side note I believe you can still do useful conversions at less then 1:1 ratios, I think 1:5 was thought to still be reasonably workable. At least, that is what I've heard.

taw said...

Random relevant quotes:

* The short chain n−3 fatty acids are converted to long chain forms (EPA, DHA) with an efficiency of approximately 5% in men, and at a greater percentage in women.
* The use of ALA labelled with radioisotopes suggested that with a background diet high in saturated fat conversion to long-chain metabolites is approximately 6% for EPA and 3.8% for DHA. With a diet rich in n-6 PUFA, conversion is reduced by 40 to 50%. It is thus reasonable to observe an n-6/n-3 PUFA ratio not exceeding 4-6.
* Vegetarians and vegans have substantially lower levels of DHA in their body, and short-term supplemental ALA has been shown to increase EPA but not DHA. However, supplemental preformed DHA, available in algae-derived oils or capsules, has been shown to increase DHA levels.
* It is generally assumed that linoleic acid (LA; 18:2, n−6) reduces EPA synthesis because of the competition between α-linolenic acid and LA for common desaturation and elongation enzymes.
* This necessitates that n−3 and n−6 be consumed in a balanced proportion; healthy ratios of n−6:n−3 range from 1:1 to 4:1 [...] Typical Western diets provide ratios of between 10:1 and 30:1 - i.e., dramatically skewed toward n−6
* And a funny if unrelated tidbit: Soybeans are the largest source of edible oils in the U.S., and 40% of soy oil production is partially hydrogenated.

You're right that there's nothing magical about 1:1 ratio, but we're very far from it.

My point is mostly that it's essentially impossible to get enough DHA via normal diet. This is very much unlike situation with all vitamins, minerals, and other microelements. We need supplementation, drastic diet changes, or GMOs.

Quickshot said...

GMO sounds like a good path in this case, either that or they need to make it a standard supplement in food. I'm already buying foods where they add Omega-3 myself and I've been somewhat careful to note which ones actually. A lot of the types certainly are ALA, which as you noted is the least useful one. With this new information I'll just know I'll have to try and be more discriminating yet if possible. Either that or just get supplements.

Though one is left to wonder... has this been a problem for millennia perhaps? It isn't like a lot of people have had access to fish or other kinds of sea food is a long long time now.

pon said...

"Supplements are waste of money"
"
# Get supplements;
# Or eat a lot of fish and other seafood;
...
"
So, are they waste of money or not?
Or maybe i've missed something?

taw said...

Quickshot: Supposedly such extreme omega 3:omega 6 ratio are extremely recent, and they used to be more balanced before modern industrial agriculture.

taw said...

pon: "All omega-3/omega-6/omega-9 supplements are waste of money"

I'm talking about those mixed all-omegas supplements here. You'd be surprised how many of those exist.

It makes absolutely no sense to get them. Either get omega-3-only supplementation (and preferably one with a lot of DHA/EPA, not just loads of ALA), or none.

got mercury said...

An excellent tool to gauge how much potential mercury is in the fish you are eating is the free on-line calculator found at www.gotmercury.org

Wassel said...

Lamb and bull testicles are very rich in DHA and very cheap. This dietary source is not well documented but try to dig further...

best omega 3 said...

I am looking for this kind of post for over a day now. I really want to know what the best sources of omega 3 are. I am so glad that I found this useful article.

Tony - FoodsforLife said...

Trouble is with fish oil supplements is that far too often you end up paying cocaine prices for fish lard.

Quite often fish oil is 75% saturated fat not pure EPa DHA

It's also high risk of contamination from heavy metals and PCBs

Omega 3 Algae DHA ( also suitable for Vegetarians and vegans) is a more reliable v pure source of sustainably farmed, toxin free, ethical choice of pure omega 3 dha epa

Bastard said...

Cod roe is really cheap and quite popular in Northern Europe. But I personally don't like it...

The new Monsato omega-3 soy is dodgy. It produces SDA http://en.wikipedia.org/wiki/Stearidonic_acid rather than EPA/DHA - but since the omega-6's compete for the delta6 desaturase it could mean that it circumvents the restrictions on human production of EPA. Remains to be seen.
Canola is an example of a pretty good oil produced by human selection for good fatty acid composition. Unfortunately it is hexane extracted and hydrogenated so it doesn't really matter. Still not worth eating.

Thanks for this post! It's awesome.

Anonymous said...

Well done on your work on this vital topic however, your research is flawed mainly due to EITHER (a) your complete reliance on one single flawed reference source OR (b) promoting your preconceived conclusion or personal political agenda regarding Genetically Modified Organisms [GMOs] which is tainting your research or (c) BOTH.

The reason fish and fish oils are so rich in Omega-3 fatty acids, particularly DHA, is because fish consume large quantities of marine Algae and/or Algae-eating organisms which is extremely high in Omega-3s. Since Algae is a plentiful bio-mass, can also be laboratory produced, and has fewer contamination issues than fish, it's a sustainable, viable source of Omega-3s in particular DHA. It's also currently being produced and sold as a supplement.

Additionally, Krill [and therefore Krill Oil], is low on the food chain, one of the largest single species bio-masses on earth, very high in Omega-3s and is generally found in clean, cold, arctic waters making it an excellent source of Omega 3's and DHA. Omega 3 supplements from Krill Oil are readily available.

Since you've recognized and stated that "hard evidence of anything about diet is essentially nil" you must also realize that the field of GMO in agriculture is poorly researched, a relatively new field, and dominated by Monsanto which as a corporation, is motivated by profit, not humanitarian motives. Before we allow the entire human food supply to be altered forever in ways which we don't comprehend and which may be potentially FAR MORE IRREVOCABLY TOXIC to the human race than anything we've ever experienced to date, your unsupported, offhand enthusiastic endorsement of GMO foods combined with your snide terminology [Luddites] toward those who don't share your enthusiasm for experimenting on the agricultural supply of food plants by those who are motivated to sterilize them for profit, leads me to believe your motives probably not to be research into Omega-3 fatty acids.

taw said...

Anonymous: Supplements like krill oil or algae oil are not real food, so they don't count here. You could presumably make some real food out of them, but nothing like that is commercially available.

The source I'm using (USDA) is the same source everybody else uses - if you don't trust it, then you cannot trust any kind of nutritional information on any food whatsoever, organic, or whatever else.

GMOs are completely safe, you Luddites should learn some real science, or go back to hunting and gathering.