Wednesday, December 3, 2008

Polyunsaturated Fat Intake: What About Humans?

Now we know how to raise a healthy pig or rat: balance omega-6 linoleic acid (LA) and omega-3 alpha-linolenic acid (LNA) and keep both relatively low. LA and LNA are the most basic (and shortest) forms of omega-6 and omega-3 fats. They are the only fats the body can't make on its own. They're found in plant foods, and animal foods to a lesser extent. Animals convert them to longer-chain fats like arachidonic acid (AA; omega-6), EPA (omega-3) and DHA (omega-3). These long-chain, animal PUFA are involved in a dizzying array of cellular processes. They participate directly as well as being further elongated to form eicosanoids, a large class of very influential signaling molecules.

AA is the precursor of a number of inflammatory eicosanoids, while omega-3-derived eicosanoids tend to be less inflammatory and participate in long-term repair processes. A plausible explanation for the negative health effects of LA-rich vegetable oils is the fact that they lead to an imbalance in cellular signaling by increasing the formation of AA and decreasing the formation of EPA and DHA. Both inflammatory and anti-inflammatory signaling are necessary in the proper context, but they must be in balance for optimal function. Many modern diseases involve excess inflammation. LA also promotes oxidative and nitrosative damage to organs, as explained in the last post. This is an enormous oversimplification, but I'll skip over the details (most of which I don't know) because they could fill a stack of textbooks.

How do we raise a healthy human? Although I think pigs are a decent model organism for studying diet and health as it relates to humans, they don't have as much of a carnivorous history as we do. You would expect them to be more efficient at converting plant nutrients to their animal counterparts: carotenes to vitamin A, vitamin K1 to K2, and perhaps short-chain polyunsaturated fats (PUFA) to long-chain fats like AA, EPA and DHA. I mention it simply to point out that what goes for a pig may not necessarily go for a human when it comes to fatty acid conversion.

I've dug up a few papers exploring this question. I don't intend this post to be comprehensive but I think it's enough to get a flavor of what's going on. The first paper is an intervention trial comparing the effect of flax oil and fish oil supplementation on the fat composition of red blood cells. Investigators gave volunteers either 1.2 g, 2.4 g or 3.6 g (one teaspoon) flax oil per day; or 0.6 g or 1.2 g fish oil per day. The volunteers were U.S. firefighters, who otherwise ate their typical diet rich in omega-6. Flax oil supplementation at the two higher doses increased EPA, but did not increase DHA or decrease AA significantly. This suggests that humans can indeed convert some ALA to long-chain omega-3 fats, but adding ALA to a diet that is already high in omega-6 does not reduce AA or increase the all-important DHA.

The fish oil supplement, even at one-sixth the highest flax oil dose, increased EPA and DHA to a greater extent than flax oil, and also decreased AA. This shows that fish oil has a greater effect than flax oil on the fat profile of red blood cells in the context of a diet rich in omega-6. Another study also found that ALA intake is not associated with EPA or DHA in blood plasma. This could suggest either that humans aren't very good at converting ALA to longer n-3 fats, that the pathways are blocked by excessive LA or some other factor (a number of things block conversion of omega-3 fats), or that our bodies are already converting sufficient omega-3 and fish oil is overkill.

What happens when you reduce omega-6 consumption while increasing omega-3? In one study, participants were put on a "high LA" or "low LA" (3.8% of calories) diet. The first had an omega-6 : omega-3 ratio of 10.1, while the second had a ratio of 4.0. As in the previous intervention study, EPA was higher on the low LA diet. Here's where it gets interesting: DHA levels fell precipitously throughout the study, regardless of which diet the participants were eating. This has to do with a special requirement of the study diet: participants were not allowed to eat seafood. This shows that most of the DHA in the blood is obtained by eating DHA from animal fat, rather than elongating it from ALA such as flax oil. This agrees with the finding that strict vegetarians (vegans) have a low level of DHA in blood plasma.

In another intervention study, researchers achieved a better omega-6 : omega-3 ratio, with participants going from a baseline ratio of 32.2 to an experimental ratio of 2.2 for 10 weeks. The change in ratio was mostly from increasing omega-3, rather than decreasing omega-6. This caused an increase in serum EPA and DHA, although the DHA did not quite reach statistical significance (p= 0.06). In this study, participants were encouraged to eat fish 3 times per week, which is probably the reason their DHA rose. Participants saw a metabolic shift to fat burning, and an increase in insulin sensitivity that was on the cusp of statistical significance (p= 0.07).

I think what the data suggest is that humans can convert short-chain omega-3 (ALA) to EPA, but we don't efficiently elongate it to DHA. At least in the context of a high LA intake. Another thing to keep in mind is that serum PUFA are partially determined by what's in fat tissue. Modern Americans have an abnormally high proportion of LA in their fat tissue, sometimes over 20%. This contributes to a higher proportion of omega-6 and its derivatives in all tissues. "Wild" humans, including our paleolithic ancestors, would probably have values in the lower single digits. LA in fat tissue has a half-life of about 2 years, so restoring balance is a long-term process. Omega-3 fats do not accumulate to the same degree as LA, typically comprising about 1% of fat tissue. At this point, one could rightly ask: we know how diet affects blood polyunsaturated fats, but what's the relevance to health? There are multiple lines of evidence, all of which point in generally the same direction in my opinion.

There are associations between omega-6 intake (from vegetable oils), low omega-3 intake, and a number of health and psychiatric problems. Another line of evidence comes from intervention trials. The Lyon diet-heart study was one of the most successful intervention trials of all time. The experimental group increased their intake of fish, poultry, root vegetables, green vegetables, bread and fruit, while decreasing intake of red meat and dairy fat. A key difference between this study and other intervention trials is that participants were encouraged to eat a margarine rich in omega-3 ALA. In sum, participants decreased their total PUFA intake, decreased omega-6 intake and increased intake of ALA and long-chain omega-3s. After an average of 27 months, total mortality was 70% lower in the intervention group than in the control group eating the typical diet! This effect was not seen in trials that encouraged vegetable and grain consumption, discouraged red meat and dairy fat consumption, but didn't alter PUFA intake or the omega-6 : omega-3 ratio, such as the Women's Health Initiative.

As usual, the most important line of evidence comes from healthy non-industrial cultures that did not suffer from modern non-communicable diseases. They invariably consumed very little omega-6 LA (3% of calories or less), ate a roughly balanced amount of omega-6 and omega-3, and had a source of long-chain (animal) omega-3. They did not eat much omega-3 from plant sources (such as flax), as concentrated sources are rare in nature. Dr. Weston Price observed that cultures throughout the world sought out seafood if available, sometimes going to great lengths to obtain it. Here's an exerpt from Nutrition and Physical Degeneration about Fiji islanders:
Since Viti Levu, one of the islands of this group, is one of the larger islands of the Pacific Ocean, I had hoped to find on it a district far enough from the sea to make it necessary for the natives to have lived entirely on land foods. Accordingly, with the assistance of the government officials and by using a recently opened government road I was able to get well into the interior of the island by motor vehicle, and from this point to proceed farther inland on foot with two guides. I was not able, however, to get beyond the piles of sea shells which had been carried into the interior. My guide told me that it had always been essential, as it is today, for the people of the interior to obtain some food from the sea, and that even during the times of most bitter warfare between the inland or hill tribes and the coast tribes, those of the interior would bring down during the night choice plant foods from the mountain areas and place them in caches and return the following night and obtain the sea foods that had been placed in those depositories by the shore tribes. The individuals who carried these foods were never molested, not even during active warfare. He told me further that they require food from the sea at least every three months, even to this day. This was a matter of keen interest, and at the same time disappointment since one of the purposes of the expedition to the South Seas was to find, if possible, plants or fruits which together, without the use of animal products, were capable of providing all of the requirements of the body for growth and for maintenance of good health and a high state of physical efficiency.
Price searched for, but did not find, vegetarian groups that were free of the diseases of civilization. What he found were healthy cultures that put a strong emphasis on nutrient-dense animal foods, particularly seafoods when available. I think all this information together suggests that the optimum, while being a fairly broad range, is a low intake of omega-6 LA (less than 3% of calories) and a modest intake of animal omega-3 for DHA.

I believe the most critical element is reducing omega-6 LA by eliminating industrial vegetable oils (soybean, corn, cottonseed, etc.) and the foods that contain them from the diet. Fats from pasture-raised ruminants (butter, beef, lamb etc.) and wild fish are naturally balanced. We no longer commonly eat the most concentrated land source of DHA, brain, so I think it's wise to eat seafood sometimes. According to the first study I cited, 1/4 teaspoon of fish oil (or cod liver oil) per day is enough to elevate plasma DHA quite significantly. This amount of omega-3 could be obtained by eating seafood weekly.


theoddbod said...

what do you think the best way to raise your DHA levels would be if you were a vegetarian or were concerned about the worlds supply of fish? and you love omega-6 rich foods cause they are so delicious!just asking.

Stephan Guyenet said...


Vegetarian DHA supplements are available that are derived from algae. You are right to be worried about wild fish stocks. You can also buy fish oil from fisheries that claim to be sustainable.

There's no doubt that a big old bag of vegetable oil-fried potato chips is tasty! That's the nature of the problem. You have to decide what your own priorities are. I just try to give people information so they can make an informed decision.

If you're going to eat processed foods, you can look for foods that have vegetable oil that's lower in omega-6. "High oleic" sunflower or safflower oil will be better in this regard, as will palm oil and palm kernel oil. Just keep in mind that there's nothing that will make processed food healthy.

Berto said...

WOW. Just found this site, it's a keeper. I'm going to have to put cite some of those studies on my site as well.

I personally supplement with Optimum Nutrition Enteric-Coated Fish Oil softgels.

Any supplements that don't tell you the exact amount of DHA and EPA (like the generic one-a-day Costco ones) are worthless if you ask me!

Jeremy said...

The Western A. Price Foundation recommends against supplementing with fish oil because of the fear that PUFAs, including omega 3s, can more easily oxidize in the blood. They believe oxidized PUFAs are a major instigator of atherosclerosis.

Stephan, you would be a great guy to critically evaluate the evidentiary basis of their recommendations.

As part of the evaluation, I would especially recommend "How essential are the essential fatty acids?" by Chris Masterjohn, which is available for online purchase at

He also has a lecture on the role of cholesterol and PUFAs / oxidized LDL available at

I am not drumming up business for Chris, but I would love for others to read his stuff and evaluate how well his conclusions coincide with other pieces of evidence.

dpmsurf said...

Great Article,
You are a smart man. There are other ways to increase your Omega 3 levels - DHA and EPA - other then fish or fish oils. In fact I believe krill oil is better. Here are some of the reasons. Krill oil has more anti oxidants and better ones. Krill is supposedly a more sustainable food source. Krill oil has the omega 3 bound to phopholipids which make them more easily absorbed by the body. To Learn More About Omega 3 -> Krill Oil

Nancy said...

Just wanted to say how much I enjoy your blog and your very thought provoking postings. Keep up the great work!

I especially enjoy hearing about Dr. Ebringer. I know a lot of AS patients are following his no-starch diet and doing much better thanks to him.

Stephan Guyenet said...

Hi Jeremy,

Unless they've changed their position, the WAPF is pro-fish oil, at least in the form of cod liver oil. According to what Chris Masterjohn has written, a modest amount of cod liver oil does not increase oxidative stress, presumably because of its high vitamin A content.

I know Masterjohn and others are big on the PUFA hypothesis of atherosclerosis. I think there's some good evidence on their side. But that doesn't mean we have to avoid all PUFA, just keep it to a reasonable level like traditional cultures that didn't have cardiovascular disease (especially LA). Besides, there's a lot more to health than LDL oxidation. I haven't read Masterjohn's PUFA report, but I suspect he would agree with that.

Jeremy said...


The WAPF is definitely against supplementing with fish oil other than cod liver oil.

Sally Fallon, the WAPF leader, says

"We don't recommend fish oil under any circumstances. Just fish LIVER oil to provide A and D with a small amount of DHA/EPA. You still need to take cod liver oil for vitamin A in the Summer. If you are getting a LOT of sun, then take a brand of clo that has very little D. Don’t take the fish oil. - Sally"

This is from a recent Q&A at

If you scroll down to the comments section, there is a long quote from Mary Enig about the dangers of fish oil.


Micawber said...

Another great piece.

One thing I'm highly curious about is whether it's true, when it comes to men, that DHA is superior to EPA. (That is, that men are less able than women to derive DHA from EPA. Indeed, why doesn't everyone - men and wome - just take pure DHA?)

I've seen so many conflicting studies about this. Has anyone been able successfully to navigate the reams of research on this to figure this out?

Stephan Guyenet said...


Thanks for pointing that out. I won't pretend to have a definitive answer, and I take Fallon and Masterjohn's recommendations seriously. However, fish are widely eaten by healthy traditional cultures. The Kitavans got about one tsp of fish oil per day from the fish they ate. The Inuit got much more, as did Indians all over the NW coast of N America. Most of those groups were low- to no-carb, which could be part of the equation. The Kitavans were high-carb however. Another factor may be that unrefined traditional PUFA-rich oil like seal oil and candlefish oil contain antioxidants that protect them more than refined fish oil is protected.

One could make the argument that eating fish is different than taking fish oil. I don't know whether that's true or not. I don't see how taking a bit of fish oil with a meal would be different from eating fish, from a digestive perspective. If you have fat-soluble antioxidants in your meal, you'd expect them to protect the oil as if they were there to begin with.


Robert Brown will be better equipped to answer the question than I am, but here's what I know. Women are naturally better than men at converting ALA to DHA. This seems to be due to higher estrogen. My feeling is that our bodies are probably adapted to getting PUFAs in the way they arrive in nature- both EPA and DHA together. Although you might be able to make an argument that we're adapted to eating the brain of land animals, which I believe is richer in DHA than EPA.

Unknown said...

Last month columnist Mark Bittman wrote an interesting article about the future of fish:

And in a recent interview he mentioned he wouldn't be able to write his cookbook "Fish" (1994) today because so many of the fish used in the recipes are now endangered.

Peter N said...

Thanks for the useful info. I went out and bought wild salmon and prawns right after reading the last post. On a different note, would you consider doing a post on coffee, tea, and yerba mate?

David said...

In Lyon, it's unlikely that any of the behavioral recommendations were adhered to as such recommendations rarely are. However, the intervention group was provided with ALA rich margarine for free, so they probably used it. However, do we know that the ALA margarine replaced omega 6 fats rather than butter or saturated fats?

Robert Andrew Brown said...

Great post Stephan. Many thanks for all your hard work.

------Re position of Weston A Price Foundation and Mary Enig.------

My impression is they are pro cod liver oil over all.

Mary Enig's book includes references to using fish oil page 106.

I think their message is whole food first because it comes as a package.

Mary Enig's books Know You Fats contains a section on fish oil types, and I recollect

Here are two links from their site.

Cod Liver Oil -- Notes on the Manufacture of Our Most Important Dietary Supplement

Cod Liver Oil: The Number One Superfood

------Re Krill------

I do not know much about krill oil. If it is better in antioxidants great.

But the most powerful antioxidants are the recyclable antioxidants produced by the body, and it is essential to get the minerals A D K etc to make sure they an do their work.

THE American Heart Association recommend a gram a day of EPA + DHA combined total.

This would I suspect be expensive in Krill oil form.

I do not know enough about the digestion to address the triglyceride phospholipid question and how each is absorbed and transported.

----- Intakes -----

We heavily store Omega 6. Stored fats have increased from 3-5% mid 50s to 10-30% today.

So your omega 3 intake is working against current dietary intake and omega 6 released form stored fat.

If you had a perfect long term low Omega 6 diet occasional fish intake would be perfect.

But for us in the west our Omega 3 DHA/EPA intake requirement is higher probably 1-2 grams a day and higher for some.

This is an excellent paper which is understandable. Hibbeln is a world renowned brain lipid specialist. Lands is a pioneer in the field, and has been patiently explaining the danger of excess Omega 6 for 50 years, with evident puzzlement as to why people do not wish to open their mind to the simple truth that excess Omega 6 and lack of Omega 3 is slowly killing us.

Supplement: n–3 Fatty Acids: Recommendations for Therapeutics and Prevention
Healthy intakes of n–3 and n–6 fatty acids: estimations considering worldwide diversity1,2,3,4,5
Joseph R Hibbeln, Levi RG Nieminen, Tanya L Blasbalg, Jessica A Riggs and William EM Lands

MiguelC said...

Great post, as usual, Stephen.

Most experts agree with the savanna hypothesis and in that regard, we would have eaten more DHA than EPA (see Cordain, Watkins & Mann's 2001 excelent paper which gives good support to this theory: )

Nevertheless, as scientists, we should go by the evidence and a recent Nature paper (Marean CW, Bar-Matthews M, Bernatchez J, Fisher E, Goldberg P, Herries AI,
Jacobs Z, Jerardino A, Karkanas P, Minichillo T, Nilssen PJ, Thompson E, Watts I, Williams HM. Early human use of marine resources and pigment in South Africa during the Middle Pleistocene. Nature. 2007 Oct 18;449(7164):905-8.)
seems to give more support to the shore-based diet theory (defended by Stephen Cunnane & Michael Crawford:
Cunnane SC, Plourde M, Stewart K, Crawford MA.Docosahexaenoic acid and shore-based diets in hominin encephalization: a rebuttal. Am J Hum Biol. 2007 Jul-Aug;19(4):578-8.).

Another important piece of this puzzle giving credit to Crawford and Cunnane's theories is Iodine, which, I believe (but I am not certain of it) is higher in shore-based diets.

But on the other hand, the theory defended by Cordain and others also has some other strengths: 1) we seem to thrive better on a high Vitamin K2 diet and the best primitive sources are organ meats (eg. liver) from land mammals; 2)The only good source of choline that I know of comes from liver of land mammals; 3) Fish and shellfish have a high protein content and a fairly low fat content, which could lead to Protein toxicity, if other sources of Fat or Carbs didn't exist in the diet. A friend e-mailed me a paper pointed to him by Cordain, which talks about this: Noli D, Avery G. Protein poisoning and coastal subsistence. J Archaeolog Sci 1988;15:395–401.

This is food for thought and I don't think anyone has a definitive answer for this, which makes it morte interesting for science geeks like me. Unfortunately, some people view Nutrition as they view religion, instead of viweing it as science, so I'm happy to see that, contrary to many blogs and websites out there, you (Stephen) act in a polite, respectful and scientific manner, which I believe is the way to go, since we shouldn't attack others, simply because they have different opinions, but instead we should respect them and discuss with them, in order for knowledge to move one step forward.

All the best


Sevilla, Spain

Robert Andrew Brown said...

Thanks Miguel


I prefer the Crawford Marsh Cunnane shore line development theory.

Crawford makes the point you would have needed quite a sophisticated brain to hunt, and you need to hunt to get meat.

Choline - I looked up Choline and it is plentiful in fish.

Vit K - vitamin k is found in fish.

Iodine - Cunnane and Venturi argue that marine sources are richer in iodine. What are soil levels like in the rift valley in Africa?

Protein argument. - shoreline gatherers would have relied primarily on shore line food, shellfish.

Mussles for example are 17% carbs 23% fat and 58% protein, which is not too far from the upper limit of 50% cited in the paper.

Is the knowledge of protein poisoning based on observations of land based diet - meat?

Symptoms cited included heart disease, arthritis, osteoporosis, and cartilage loss - these are all conditions seen with excess Omega 6.

Grain fed livestock exhibits a large distortion in the Omega 3:6 balance, being high in 6 and low in 3. Does this help explain these conditions if they are meat based.

Robert Brown


Omega Six The Devils Fat

Stephan Guyenet said...


Perhaps someday, but I have no immediate plans.


Lyon participants actually ate less total PUFA, less n-6 and more n-3 than controls. 3.6 vs 5.3% LA, 0.84 vs 0.29% ALA, 5 vs 6% total PUFA. Here's a reference:


Thanks for the great links and speculation. The other possibility is that we've been eating both seafood and land food for long enough that we do well on both. I think that's supported by the anthropological evidence.

Protein toxicity is also a feature of animals that are not carnivores or haven't been for long enough that they are good at gluconeogenesis and disposing of nitrogen. Cats and dogs can tolerate more protein than we can, for example. I think you make a good point about seafood being too low in fat for us, if that's our only source of calories. It would have been fine if we were supplementing with scavenged brain/marrow, starchy tubers or some other source of fat or carbohydrate.


Protein toxicity or "rabbit starvation" occurs when protein reaches about 35% of calories. The Inuit and other carnivorous cultures knew that they would waste away if they couldn't find a source of fat for around 75% of their calories. That's why the argument that HGs ate little fat or little saturated fat falls flat. It just can't be reconciled with the numerous carnivorous HG groups.

MiguelC said...

Hi Robert,

From what I've read, I believe Protein "Poison" occurs at about 35-40% of calories, just like Stephen said. Take a look at the following papers that discuss it:

Speth JD, Spielmann KA. Energy source, protein metabolism, and
hunter-gatherer subsistence strategies. J Anthropol Archaeol 1983;2:1–31.

Speth JD. Early hominid hunting and scavenging: the role of meat
as an energy source. J Hum Evol 1989;18:329–43.

Noli D, Avery G. Protein poisoning and coastal subsistence.
J Archaeolog Sci 1988;15:395–401.

Lieb CW. The effects on human beings of a twelve months’ exclusive meat diet. JAMA 1929;93:20–2.

Rudman D, DiFulco TJ, Galambos JT, Smith RB, Salam AA, Warren
WD. Maximal rates of excretion and synthesis of urea in normal
and cirrhotic subjects. J Clin Invest 1973;52:2241–9.

Cordain L, Eaton SB, Miller JB, Mann N, Hill K. The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. Eur J Clin Nutr. 2002 Mar;56 Suppl 1:S42-52

Cordain L, Miller JB, Eaton SB, Mann N, Holt SH, Speth JD. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr. 2000 Mar;71(3):682-92

BTW, I agree with you regarding excess w6 being a problem. For those who want to read about this, I sugest papers by Artemis Simopoulos.

Stephen, From what I've read, I agree with you regarding not only the fact that maybe we wouldn't go above the protein ceiling by eating fish and shellfish, if we would add some nuts, seeds, fruits, tubers and some land animals too.

As for the fact that H/G didn't eat a low fat diet, as originally proposed by Eaton in 1985 (Eaton SB, Konner M. Paleolithic nutrition. A consideration of its nature and current implications. N Engl J Med. 1985 Jan 31;312(5):283-9.), I also think you're right and even Eaton, after starting to work with Loren Cordain and the archeologist John Speth changed his position, which culminated with a great paper (that was received with great criticism, partly because of some prejudice that exists against animal based foods in favor of vegetables and grains, which is something to be expected, given the official recommendations for Nutrition in various parts of the world) that you already mentioned in your blog a while ago:

Cordain L, Miller JB, Eaton SB, Mann N, Holt SH, Speth JD. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr. 2000 Mar;71(3):682-92

As for the estimated range of fat intake, this was 28–58% and later on, Cordain tried to estimate the saturated fat intake of H/G, based on the model presented in the AJCN paper and it may have approached 20% of total calories in some societies.

I know that saturated fat is a very controversial issue and presumably this why Cordain is so criticized, but I believe that in a complex system, such as the human body (I'm an Exercise Physiologist, obtaining a PhD in nutritional Biochemistry), we can't isolate variables.

For instance, there is some evidence that the saturated fatty acids 12:0, 14:0 and 16:0 downregulate the LDL receptor, elevating LDL, but we shouldn't forget that studies showing this have been performed in humans eating the typical high glycemic load, high w6/w3 diet. Moreover, a recent study showed that under a low carb diet, the plasma levels of saturated fatty acids were lower than under a high carb, low fat diet with less saturated fat (Forsythe CE, Phinney SD, Fernandez ML, Quann EE, Wood RJ, Bibus DM, Kraemer
WJ, Feinman RD, Volek JS. Comparison of low fat and low carbohydrate diets on circulating fatty acid composition and markers of inflammation. Lipids. 2008 Jan;43(1):65-77.).

Furthermore, Cordain came with an old theopry he had that lectins in peanuts and wheat may cause CHD (see,%20heart%20disease,%202008.pdf ) and this may be one (I enphasise one) of the possible reasons why The Masai, for instance, have extensive plaques, but they don't die from it.

This stuff is fascinating and may bring some light to this never ending discussion.

Well, I realized that I wrote a lot more than I should have.

All the best to you all and if you want, you can shoot me an e-mail at

Miguel Carrera

Robert Andrew Brown said...
This comment has been removed by the author.
Robert Andrew Brown said...

Thanks Stephan and Miguel.

I know almost nothing about this so please feel free to point out the flaws. This is off the wall thinking.

Miguel from the titles the trials look like they are primarily meat based.

Cordain said: "No hunter-gatherer population is entirely or largely dependent (86–100% subsistence) on gathered plant foods, whereas 20% (n = 46) are highly or solely dependent (86–100%) on fished and hunted animal foods." [Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets.]

This seems to be saying some diets are highly animal reliant 85% plus ?.

If protein poisoning occurs at 30-40% of calories is the conclusion from this that the animals are on the mean very high in accessible fat? Does this reflect the mean global composition of bugs and beasts?

Or is it also about the availability of the macro nutrients to metabolise the protein. (Eg A D and K which Stephan has done so much to educate us about]

Is protein poisoning also a measure of depletion of essential macronutrients.

Eg fish are much better balanced that rabbits minerals and vitamins which are presumably necessary for protein metabolism. (and does excess consumption of an animal that does not supply a nutrient deplete existing stores and bring on conditions relating to the depletion of that micro nutrient)

(Fish oil helps reduce cachexia - just a thought)

Here are two nutrient profiles, one for rabbit and one for mackerel.

Mackerel is fairly complete - Rabbit is has many gaps A D K mineral etc.

Could you eat more mackerel than rabbit before developing protein toxicity?

If it is about nitrogen what about big cats and dolphins.

December 6, 2008 3:21 AM

Robert Andrew Brown said...

This is the summary of Sally Fallon and Mary Enig views on cod liver oil in recognition of their sometimes conflicting arguments.

This is their recommendation as of June 2007 from the Weston Price site.


"Vitamin A, Vitamin D & Cod Liver Oil: Some Clarifications
by Sally Fallon and Mary G. Enig, PhD

Several visitors to our website have noted inconsistencies in various statements about vitamin A, vitamin D, and cod liver oil. These issues revolve around questions of dosage and safety.......

As a general guideline, we recommend the following doses of vitamin A from cod liver oil, along with a nutrient-dense diet that contains other vitamin A-rich foods:

Children age 3 months to 12 years: A dose of cod liver oil that provides about 5000 IU vitamin A daily
Children over 12 years and adults: A maintenance dose of cod liver oil that provides about 10,000 IU vitamin A daily
Pregnant and nursing women: A dose of cod liver oil that provides about 20,000 IU vitamin A daily

Individuals under stress or wishing to use cod liver oil to treat a disease condition may take much larger doses, even up to 90,000 IU vitamin A per day, for a period of several weeks."


Dr. B G said...


It's very interesting that you bring up peanuts (and lectins) which are part of the legume family (not nuts/seeds). (and worrisome b/c my father and I are big big peanut fans)

Robb Wolf is pretty adamant about eschewing all legumes (even soaked/well cooked ones) including peanuts. For those with non-silent celiac, I think this could make a mild difference. Even baking with garbanzo bean flour is not really permissible if one is vigilant *sigh*.

Thanks for the info and good luck on your PhD!


MiguelC said...

Dr. BG, thanks for the support and I tend to agree with Robb Wolf that legumes (and you're right to point out that peanuts are legumes)and gluten containing grains (such as wheat, rye, barley and, probably, oats) should be avoided by people with specific HLA haplotypes that predispose them to auto-immune diseases and I believe that Robb has learned about this while working with Cordain, who has published some papers and articles on that (bear in mind that these were published almost 10 years ago):

Here are some other papers on grains, lectins and auto-immune diseases I enjoyed:

Jönsson T, Olsson S, Ahrén B, Bøg-Hansen TC, Dole A, Lindeberg S. Agrarian diet and diseases of affluence--do evolutionary novel dietary lectins cause leptin resistance? BMC Endocr Disord. 2005 Dec 10;5:10.

Kagnoff MF. Celiac disease: pathogenesis of a model immunogenetic disease. J Clin Invest. 2007 Jan;117(1):41-9

McGough N, Cummings JH. Coeliac disease: a diverse clinical syndrome caused by intolerance of wheat, barley and rye.
Proc Nutr Soc. 2005 Nov;64(4):434-50

Frisk G, Hansson T, Dahlbom I, Tuvemo T. A unifying hypothesis on the development of type 1 diabetes and celiac disease: gluten consumption may be a shared causative factor. Med Hypotheses. 2008;70(6):1207-9

I also suggest a look at Direct Ms website


You bring very interesting questions to which I don't have a definitive answer, but I believe that protein toxicity occurs above 40% of total calories, independently of the amount of micronutrients in the diet. I think this is one reason why societies, such as the Inuit, who rely almost exclusively on animal foods, choose to discard lean tissue in favor of the fattiest portions.

All the best


I may take a while before I come back to reading and commenting on this blog (and others), since I have to colect references, read them, study them and then write a paper on Leucine, mTOR and post-exercise protein synthesis as part of my PhD.

Dr. B G said...


I'd like to read your dissertation (or crude forms *hee*) when your done/semi-done. (as yours too Mr.Stephan PhD-candidate!!! Stephan, ur gonna be SOOO BIIGGGGG I predict)

I am very interested in mTOR leucine and the relationship with PPAR-delta. Do you think Taurine (and other sulfur-AAs) also affect mTOR? I cannot find any info in these regards??? Do you do benchwork?

I've posted a little bit on my blog -- search 'PPAR delta'.

Do you work out? I've met Robb via my gig with Crossfit -- military like high intensity training. Here is my gym where we're all big fans of his. You're correct -- he is Cordain's protege +MUCH MUCH much more.

diablocrossfit (dot) com


Dr. B G said...

BTW -- thanx for the lectin links!

What are your thoughts on hGH on mTOR? They seem intimately related. As is NFKb, insulin and even vitamin D.


Robert Andrew Brown said...


Has somebody hijacked your email?

I emailed you and this was the response I got.

"Many more products for you to choose from. please check our online
shop: www. REMOVED
such as digital cameras,PSP,LCD TV,Laptops Notebooks,Digital
Video,Mp4,GPS, Motorcycles."

Stephan Guyenet said...


I'm interested in the lectin theory a well, and I've written about it some myself. There's one thing that bothers me about it though. Processing methods can remove lectins. For example, wheat germ agglutinin is nasty, but it gets removed when wheat is milled. The gluten stays of course.

Beans are full of lectins, but they are reduced or eliminated by long soaking followed by cooking. Same for non-gluten grains. Fermentation is particularly effective for removing anti-nutrients. So I think when we talk about the health properties of grains and legumes, we really have to take the preparation method into account. Traditional cultures knew exactly how to make grains and beans digestible, even though they didn't know what lectins, phytate, tannins, saponins etc. were specifically.

I guess what I'm trying to say is sometimes I think Cordain throws the baby out with the bathwater: I agree with him that modern processed grains and legumes are unhealthy, but I'm not convinced that they can't be rendered healthy by traditional preparation methods.

gunther gatherer said...

Ok, here's a far-out question for Stephen and Robert Brown.

Most soaps are plant-oil based, presumably with a high Omega-6 content, depending on the particular scent, ingredients, etc. We use them every day, several times a day in the western world. Is this another avenue for high omega-6 intake?

Stephen, do you know anything about how oils get through the skin and if they get into the system in detectable amounts? I would think scrubbing out skin (the largest organ of the body, and very porous) every day with this stuff is NOT a paleolithic charactistic, and not even 200 years old for most human populations.

It stands to reason that if we're all switching to organic soaps these days because we want to avoid additives and pollutants getting into our bodies through the skin, perhaps we should be considering alternative oils for these soaps as well, such as coconut (MUFAs instead of PUFAs) or even animal fat.

Anyone have any ideas on this?


gunther gatherer said...

Sorry, the above should have coconut oil as containing saturated fat and MUFAS.

In any case, are any readers/commenters here using saturated and monounsaturated fats for their soaps, and how are you managing this?


Stephan Guyenet said...


Good thought. Soap is hydrophilic enough that I think 99.9% of it washes off the skin and down the drain. So I doubt it would contribute to our n-6 intake. But who knows what the additives are doing to the skin. And also the effect of removing the natural skin oils daily and replacing them with an artificial moisturizer in some cases.

My policy is, don't put on your skin what you wouldn't put into your mouth. Some fraction of it will end up there anyway.

Chris Kresser said...

A little late to the game here, but a few questions:

1) Is there any meaningful difference between the DHA derived from fish oil and that derived from algae in the vegetarian supplements?

2) Are there any vegetarian sources of EPA (I don't think so)?

We know the ALA to EPA/DHA conversion doesn't work well for most people, so guzzling flax oil probably isn't the answer for vegetarians (I'm not one, BTW!)

I've read that DHA can be converted to EPA, but that is also not an efficient process.

So what would the recommendation be for a vegetarian? They can take an algae-based DHA supplement, but are they out-of-luck for EPA? Is EPA necessary if they're getting sufficient amounts of DHA - especially for males?

Unknown said...

Have you ever tried krill oil? My friends say that it is better than fish oil. They even gave me this link: I think it's worth watching. And I'll definitely buy krill oil supplements soon. :)

Amir Timur said...

Here in INdia, I commonly get a whole pastured cow/buffalo brain that weighs more than a pound for about a dollar. Cooked with onions, ginger, garlic, turmeric, garam masala, and cilantro in ghee, can I eat this everyday for breakfast? Maybe 1/3rd-half a brain mixed with an egg or two? Would that be unhealthy? OR maybe alernate with liver (half a dollar a pound)cooked in tallow(1$/kilo)
Is it ok or can it be too much of a good thing?

Amir Timur said...

Is it safe to eat a beef brain (70% grass fed) every two days? 1 pound with 20 gms of pure cholesterol and 6 gms of omega 3s?
Would the omega 3s be inflammatory and dangerous, as Ray peat says?
Would the cholesterol and steroids work against the inflammation?
Looking forward to some clarity.