Thursday, March 18, 2010

Arctic Paleo Diet: Modern Foods Can't Replicate An Inuit Diet

As we have discussed possible Inuit diet profiles for their nutrient contents relevant to bone health in the series pertaining to Eskimo Diet and Health, I have come to realize that the idea that you can replicate Inuit diet and health by eating a diet composed of any selection of modern meat and fat does not hold water.  For example, thanks to help from Greg, we found that to ensure adequate intake of manganese, Inuit had to eat shellfish; that a diet of meat and finfish alone fell short.

This fact came very clear to me when I read through the paper on vitamin C in the Inuit diet discovered by my able commenter Greg (Thanks Greg!): "Vitamin C in the Inuit diet: past and present," a master's thesis  written by Karen Fediuk of the School of Dietetics and Human Nutrition at McGill University, Montreal, Canada, July 2000.

This paper demonstrates that the Inuit ate a variety of wild plant and animal tissues that supplied vitamin C.   Further, even if you assume that Inuit only ate animal products most of the time, many of the marine animal tissues they consumed had very significant contents of vitamin C not found in modern livestock products, even from grass-fed animals.

For example, among common traditional Inuit foods, cisco eggs contain ascorbic acid at levels of 49mg/100g, whale skin 36mg/100g, and ringed seal brain up to 28mg/100g.  Compare these to spinach supplying ascorbic acid at 51mg/100g, oranges at 50mg/100g, cabbage at 47mg/100g, and tangerines at 31mg/100g.

Frozen and raw muscle meats consumed by Inuit contain ascorbic acid at 1mg/100g on average. In contrast, modern muscle meats generally supply no vitamin C at all in a 100g portion, and liver only about 20-30mg/100g.

Fediuk found that in a traditional Inuit diet, absent modern foods, vitamin C intake would range from 90mg/d up to 262mg/d, depending on season (table 13.5 from her thesis below):

This is plenty not only to prevent scurvy, but also to provide some of the benefits that accrue from higher tissue saturation with vitamin C.  In winter and spring, the sources of vitamin C for Inuit distribute as shown in this figure from Fediuk's paper:


In winter, kelp, boiled ringed seal meat, raw whale skin, and raw ringed seal meat provided 92% of Inuit winter intake of vitamin C, which according to the table above amounted to 90mg/d.  So these 4 items provided them with >80mg of vitamin C.  In late spring, raw whale skin provided 71% of their vitamin C intake, with mussels providing the next largest share at only 10% of the total 185mg/d intake (from table above).  That means the whale skin alone provided 131mg of vitamin C per day.  I know of no product of modern, even grass-fed, livestock that will come anywhere close to this (if anyone else does, please let me know).

In contrast, someone eating a strictly carnivorous meat-and-fat diet composed of modern livestock meats, even if strictly grass-fed, would not consume anywhere near this amount of vitamin C on a daily basis.  Therefore, a modern "zero carb" diet composed of terrestrial livestock is not a replica of an Inuit diet, and we can't expect it to produce the same health outcomes of a traditional Eskimo diet.

As I noted in Masai Use of Herbs, to replicate the diet and health of the Masai you have to eat the same quality of food (grass-fed cattle products) and use the herbs they use.  Similarly, to replicate the diet and health of the precontact Inuit (if that was desirable) would require eating exactly the same variety and types of foods as the Inuit ate–shellfish, fish with bones, seal eyeballs, walrus liver, seal brains, whale skin, kelp, berries, partially digested contents of caribou stomachs, and so on–in proportions similar to what Inuit ate.

If you do something different from the Eskimo diet, you can't rationally expect that you will have the same results.  Eskimos' experience certainly did not prove that a diet of modern meat and fat will keep you healthy without plant food intake.

One last interesting aspect of this paper.  According to Stefansson, Eskimos ate a diet providing 70-80% of energy as fat and only 20% as protein, claimed to be required to prevent protein poisoning.  Others have claimed that humans can tolerate no more than 35% of calories as protein for extended periods of time due to limits on the liver's ability to synthesize urea from waste nitrogen, and I have taken this as a demonstrated fact.

Therefore, I was surprised to find the following table in Fediuk's thesis:



The sources she cites estimated the coastal Inuit diet providing a minimum of 43% of calories  and a maximum of 56% as protein, and fat ranged from only 43% to 53%.  These figures all have carbohydrate intake of less than 7%, so I don't think we can dismiss them as results of incorporation of modern carbohydrates (i.e. post-contact diets).  They describe the Inuit diet as having roughly equal caloric portions of protein and fat, not the modern high-fat low-carb diet.

A 3000 kcalorie diet (necessary for a young active hunter) providing 43% of calories as protein contains 322g of protein; with 56% protein it would provide 420g of protein.  This exceeds levels Stefansson claimed and apparently demonstrated (in Effects on humans of 12 months exclusive meat diet) to be acutely toxic, at least in his own case. 

I will have to do some more research to determine whether protein intakes of this level (twice what I proposed in my models of Inuit diet), from meat (not purified proteins) could have any influence on bone mass.  It has been my impression so far that  studies supposedly proving that dietary meat protein has no detrimental effect on bone health have utilized much lower protein intakes in the range of 2-3 times the RDA, whereas if this data is correct, the Eskimos were consuming 6-10 times the RDA.

18 comments:

Monica said...

Great article, Don. I appreciate and enjoy your writings.

I'm getting almost as tired of the 100% carnivore low carbers as I am the vegans. Both groups are living in a fantasy world. For one, animal products have no value or place in the human diet. Same with the carnivores. The difference it that the carnivores don't have a radical ideology and aren't attacking anyone with cayenne-pepper laced pies, I guess. :)

Don said...

Monica,

Not sure I understand this part of your comment:

"For one, animal products have no value or place in the human diet. Same with the carnivores."

Can you clarify?

Monica said...

Badly, badly phrased, Don.

I meant to say that this is what the vegans are asserting, and that the carnivores are asserting the opposite: that plant foods have no place in the human diet. It's all just so silly and contrary to what we know about human evolution.

Greg said...

Glad you found my comments helpful!

So we can't reproduce the effects of an indigenous diet by eating *just* (modern lesser versions of) a limited selection of what they ate. If we don't eat offal, etc we must come up with alternatives.

I wonder about the validity of alternatives that don't have an indigenous analogue. Green leafy vegetables are supposed to cure everything now, but I think it would be difficult for us to find those being consumed in indigenous cultures in large quantities. I worry that we will be to sure of ourselves and pick the wrong replacements.

Stephan said...

Well done Don.

I'm skeptical of the protein numbers in that figure you posted. I wonder how that was calculated. Was it measured directly or guessed based on portion sizes and estimates of food macronutrient composition? Did it include the seal oil that many groups used as a condiment?

On the other hand, the 35% protein ceiling figure is something I got from one of Cordain's papers. When I followed the ref, it took me to a paper that IIRC was an acute feeding study that calculated max N excretion in a somewhat hypothetical manner. Maybe there is some adaptation that happens over time and the true protein ceiling is higher. As you noted before though, protein is a poor calorie source if you're using it for glucose. So if they ate 40-50% of cals as protein, it would probably have been because fat and carbs weren't sufficiently available.

The strange thing to me is that even lean animals are almost half fat by cals. Given the amount of fat walking around in the arctic, I find it bizarre that they would have eaten so much protein. Maybe the researchers tended to study them in summer (for convenience) when the animals were leaner.

Greg said...

I do believe the macro-nutrient table is in grams. That would put the fat/protein split at 70/30 by calories. Not quite as high a ratio as Steffanson would have liked. Adding the carbs in would put the highest protein intake report at 35% and lowest at 25%

Don said...

Greg,

Re the macronutrient table, I think you are right. I misunderstood her explanation of the figures in the table.

Flowerdew Onehundred said...

Very interesting. I do think that the beef-and-water people are missing some vital nutrients. Any culture that ate zero carb ate a lot of other animal products - offal, the Masai drank blood, and the sea offers very different macronutrient profiles than terrestrial animals.

It takes many years for these deficiencies to show up in a big way - look at how long Lierre Keith went as a vegan before waking up to reality.

I see a lot of paleo types that seem to only eat lean muscle meat. I've really been trying to eat bone broths (esp. the gelatinous part), skin (including plain pork rinds), marrow etc. I'm still kind of afraid of offal, but I will at least put the organs into my next bone broth.

I also don't think that eating low-carb paleo is necessarily the right way to go, at least not long-term. The studies based on Cordain seem to have been done on people eating fruit and even a bit of honey.

Martin Levac said...

Protein becomes toxic only when not enough fuel, either fat or carbs, are eaten with it. Fresh meat cures scurvy. The Eskimos used to take only the back fat and the hide when they could not carry the entire animal. What of pemmican? What of the Stefansson all meat trial? What is the basis for the RDA and how does this apply to somebody who eats only fat meat and water?

Look I don't know who said the Inuit diet was the best and it doesn't matter. The Inuit are not the sole example of humans who maintained perfect health indefinitely by eating an all meat diet. If you refute the Inuit idea, fine but you got a whole lot more to refute before you can score points against the general idea of a carnivorous human diet.

Tell me, why would an all meat diet be sub-optimal when dietary carbohydrate is not essential for us to maintain perfect health indefinitely? From the Stefansson all meat trial, we know that dietary carbohydrate is not essential to our well being. From this knowledge, we reason that we are not the descendants of those for whom dietary carbohydrate was essential to their well being.

From the Stefansson all meat trial, we know that fresh meat cures scurvy. That should settle any doubt as to the anti-scorbutic quality of animal flesh, regardless of how much vitamin C it contains. Or rather, whatever fresh meat contains must be enough. It seems rather pointless to argue between "sub-optimal" and "enough" at this point.

Don said...

Martin,

1) Eskimos didn't have "perfect health." Early osteoporosis is well documented. They may also have had more hemorrhagic stroke.

2) Most Eskimos did not eat only meat, and those who did eat only meat had the most signs of bone disorders in old age.

3) Name the other tribes who ate only meat, i.e. never ate any other plant foods or herbs.

4) Vitamin C is not the only nutrient of concern in an all meat diet.

5) All mammals have the ability to go without dietary carbohydrate. This is an adaptation to starvation, essential for surviving when no food is available. Sheep can survive without dietary carbohydrate also, by burning their own protein; this doesn't prove that they descended from carnivorous ancestors. The ability to survive without dietary carbohydrate does not prove that humans descended from purely carnivorous ancestors.

6) Stefannson's trial lasted one year. It says nothing about the life long effects of an all meat diet. Stefansson also did not eat only muscle meat, his menu included organ meats and brains that include vitamin C at levels not found in muscle meat. He also had increased tartar on his teeth at the end of the experiment, suggesting increased tissue levels of calcium which arise from bone resorption.


7) If the human is designed for a meat only diet, you will have to explain how Kitavans can live in excellent health to 100 years of age on a diet containing 69% of energy from carbohydrate and only 10% from protein. Cats are designed for an all meat diet for certain, and such a diet would result in early death for a cat.

Moreover, if a cat faces starvation, he doesn't turn to eating plant foods to survive. But humans all over the planet, including Eskimos, choose to eat plant foods when available. Even in wealthy countries where people could choose to eat only meat and fat, they choose to eat plants. This fact argues strongly against the idea that humans are by nature strict carnivores.

Sorry, the claim that humans are strict carnivores or descended from strict carnivores is extraordinary, I don't know of any anthropologist or primatologist who would support the claim, and extraordinary claims require extraordinary evidence. So far I haven't seen such evidence.

Don said...

Martin,

I remembered, I wanted to add that if you go to PubMed and search "ketogenic diet mice" you will find at least 20 studies done implementing a ketogenic diet in mice. Yes, mice can live on a carbohydrate-free diet, but this does not prove that mice are designed for a strictly carnivorous diet or descended from strictly carnivorous ancestors.

Martin Levac said...

From my own readings, the Inuit/osteoporosis argument is contentious at best. Anyway, you can't blame an all meat diet for the Inuit's osteoporosis if you also claim that the Inuit did not in fact eat an all meat diet. If anything, your Inuit's osteoporosis is due to the mixed diet your Inuit ate. Further, I read somewhere that calcium must ride a protein to enter the cell. How can an all meat diet, which is obviously full of protein, cause a calcium deficiency and thus osteoporosis? The mechanism is not even there at the cellular level.

The Stefansson all meat trial gives exactly zero indication that something will go wrong after one year. On the contrary, when something did go wrong, it was due to straying away from an all meat diet. Stefansson even admitted years later that he returned to an all meat diet and returned to good health as a result, indicating that something went wrong on a mixed modern diet, and that nothing is wrong with an all meat diet. But where does the doubt come from if not from within the trial itself? It's easy to find out if they measured calcium balance to see if it would cause osteoporosis.

Whether Stefansson ate organ meat is besides the point: He did not eat an Inuit diet and still maintained perfect health for the duration of the all meat trial. How can we maintain the argument that since we can't replicate an Inuit diet, we can't benefit from a diet that closely approximates it fundamentally, i.e. all meat?

From a natural selection perspective, the non-essential nature of dietary carbohydrate to humans as shown by the Stefansson all meat trial demonstrates that we are not the descendants of those for whom dietary carbohydrate was essential.

That we are not the descendants of those for whom dietary carbohydrate was essential does not mean we have lost the ability to extract nutrition, albeit poorly and inefficiently, from dietary carbohydrate. It simply tells us that at some point we had to eat plants. But our peculiar ability to survive on meat alone tells us that we had to survive on meat alone at some point and probably for periods long enough to kill off any individual who could not do it.

I'm not sure about your argument about mammals and their ability to survive on meat alone. I'll have to read about it. However, at first glance, I don't see carnivores choosing to eat plants even when they have exactly zero meat to choose from. Nor do I see herbivores choosing to eat meat even when they have zero plants to choose from. But maybe the argument is valid for omnivores so I'll give you that.

At least, the argument about vitamin C is done and done. What other nutrient is contentious in an all meat diet? With the Stefansson all meat trial, even though it lasted for one year, if there had been any deficiency whatsoever, it would certainly have shown up by the end of that year. Conversely, when we look at other food trials that look at mixed diets, we see clear deficiencies that develop much more quickly than one year. For example, the Ancel Keys semi-starvation experiment and the Biosphere 2 project.

You didn't address the RDA question. What is the basis for the RDA and how does that apply to those who eat an all meat diet? As far as I know, there is just about no data on that. The basis for the RDA is a mixed diet. Since a mixed diet causes deficiencies, and an all meat diet does not, how can the RDA apply to an all meat diet? What we have to do is find out what is in the meat that allows us to maintain perfect health indefinitely, then we can say that's what we absolutely need to do so. We can't just translate the current RDA to an all meat diet and expect it to be a reflection of reality.

Martin Levac said...

The Stefansson all meat trial was supposed to answer all the questions and doubts at the time which were born out of the observations about the Inuit, their diet and their health. There was an army of scientists involved who incidentally made all kinds of doomsday predictions that never came true. The doubts and questions at the time are the very same doubts and questions you and others have today. It's my opinion that this trial did answer all the doubts and questions, and subsequently refute all the hypotheses that said the trial would fail. Why then does doubt persist?

Interestingly, the last rampart of the opponents of an all meat diet is that we must eat organ meat. It is the only hypothesis/doomsday prediction that survived the trial. It is the only hypothesis that was not tested by this trial.

Fred Hahn said...

Is it just vitamin C that is the issue?

Don said...

Fred,

No, I think potassium, magnesium, and possibly boron intakes were also marinal among most Inuit, and among some (northern inland groups) calcium may also have been marginal, and may account for their pretty well-documented propensity to early onset osteoporosis. See my other posts on Eskimo diet and health.

Martin,

I just disagree with you. In this post:

http://donmatesz.blogspot.com/2010/03/paleo-diet-ph-does-it-matter-part-vii.html

I explain why the Stefansson all meat trial did not resolve questions about calcium nurtriture. Further, as I pointed out here:

http://donmatesz.blogspot.com/2010/03/paleo-diet-ph-does-it-matter-part-ii.html

and here:

http://donmatesz.blogspot.com/2010/03/paleo-diet-ph-does-it-matter-part-iii.html

We have very good evidence that pre-contact Eskimos had prevalent osteoporosis.

Further, my post on Kitavans shows that your claim that "mixed diets cause deficiencies" is simply false. You compared Stefansson's calorically adequate diet to two experiments in which people were put on calorically restricted mixed diets, i.e. starvation. By definition those result in deficiency. If Stefansson had eaten only half as many calories as he did, he would have suffered several deficiencies as well.

darwinstable said...

Brilliant post and undeniable evidence that today we cannot replicate the Inuit diet. For some reason this group is always touted as THE hunter gatherer group for some reason. I always felt they were making the best of a bad situation. Anyway very very interesting and confirms my doubts. Thank you.

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