Saturday, February 27, 2010

Paleo Diet pH and Eskimo Health – Part I

Since the human genome developed primarily in adaptation to an African equatorial ecological niche over the course of more than 2 million years, and other hunter-gatherer diets developed subsequent to the diaspora out of Africa some 50K years ago, I think that contemporary African or equatorial hunter-gatherer diets more likely represent the human evolutionary diet than, say, the Inuit diet.

Put otherwise, if the human lineage developed for 2 million years in Africa, then (for sake of argument) began living in the arctic 50 thousand years ago, the genome spent 98% of its developmental time in Africa, and only 2% in other ecological niches.  Since the primate lineage leading to humans really extends back more than 6 million years in Africa, the time “out of Africa” amounts to far less than 2% of the time during which the human genome has evolved.

When we look at contemporary African or other equatorial hunter-gatherer diets, we find a significant intake of plant foods.  For examples take a look at the following table:

Tribe Latitude % Animal Food % Plant Food
Efe 2° N 44 56
Gwi 23° 26 74
Hadza 3° S 48 52
San (!Kung) 20° S 68 32
San (!Kung) 20° S 33 67
Aborigines 12° S 77 23
Aché 25° S 78 22
Nukak 2° N 41 59
Onge 12° N 79 21

Note that this table has two different reports for the San (!Kung) because two different researchers—Yellen (1977) and Lee (1968)—have reported different values, possibly reflecting seasonal or geographical variations.  The variation of these two reports on San diet emphasize that equatorial hunter-gatherers generally had variable intakes of plant and animal foods.  If you average the two reports for the San, you get a diet that hovers around 50% animal and 50% vegetal.

On average, these equatorial tribes obtained 46% of energy from animal food and 54% from plant foods. A hunter-gatherer diet providing 46% of energy as animal food and 54% as plant food will have a net alkaline residue due to the large amount of K-bicarbonate provided by plant foods.  

To illustrate, I created the following example of a 2000 kcal diet which derives 44% of energy from animal foods and 56% from plant foods, using the San (!Kung) diet as a model (they get about one-third of their energy from mongongo nuts; I substituted walnuts).


This slide shows the plant:animal subsistence ratio of this diet by caloric contribution:

This slide shows the plant:animal ratio by weight of the foods:

This slide shows the macronutrient distribution of this diet:

Note that although more than three-quarters of the weight of this diet consists of plant foods (1212 g), it provides only 122 g of carbohydrate which supplies only 23% of energy.  Although animal foods form only about one-quarter of the weight, they supply nearly half of the energy.  Fat provided 52% and protein 25% of energy; 77% of energy comes from protein and fat.  A diet can have three times as much plant food as animal food by weight, yet supply more than three-quarters of its energy as protein and fat and have a relatively low carbohydrate content. (For reference, on average, U.S. citizens consume about 50% of calories as carbohydrate, double the value of this H-G diet analogue.)

Finally, this slide shows the acid:base ratio of the diet:

If we take this perspective, then we would expect to find evidence of maladaptation among hunter-gatherers eating diets that diverge significantly from the African standard.  Inuit diverge more than any other tribe, with a diet providing 90% of energy from animal foods.  Compared to the African hunter-gatherer, the Inuit diet contains much less of some nutrients (e.g. vitamin C and potassium) and has a net acid, rather than the African alkaline, residue.  The question then arises, did Eskimos suffer any negative health consequences that might support the idea that the human genome adapted to a diet more like the equatorial hunter-gatherers?

I’ll deal with that in my next post.


Greg said...

Anxiously awaiting the next post!

I am often told that our modern fruit contains much larger quantities of sugar than exists in a natural environment where fruit trees have not been bred by man. It would be interesting to hear your take on this and on fruit. If true, it would reduce the carbohydrate consumption a little further than the comparison to a (modern) navel orange.

Shareef said...

Dr. Price mentioned Muhima, Watusi, Terraizeka, Neurs and Masai all amoung African tribes with remarkable health whose diets more resembled the Inuit than the !Kung

Aaron Blaisdell said...

Thanks Don. That was very informative and I'm waiting to see your analysis of how these proportions relate to health measures. I presume osteoperosis among the Inuit is one.

Although relative amount of history spent in one environmental and echological context versus another is informative, we realy can't draw any firm conclusions without knowledge about the rates of evolution; especially when those rates can be quite variable and dependent upon the selective pressures exerted by the environment. This was the premis of the 10,000 year explosion which argued that rates of human evolution, that is, changes in gene frequncies and their phenotypic effects, sped up dramatically due to agriculture and associated lifestyle.

Don said...


Some wild fruits have plenty of sugar, and H-Gs naturally selected the more palatable (higher sugar) varieties. Wild types vary mostly by having higher contents of fiber and less sour or bitter secondary compounds.

For example, Brand-Miller reports on a type of fruit eaten by Aborigines [Nutrition Research Reviews (1998), 11, 5-23]:

"Other important desert fruits include the raisins, Solanurn centrale and S. ellipticurn, which
were eaten both fresh and in the naturally dehydrated state. The dried fruit was often ground
between stones and mixed with water to a seedy paste and then compacted into balls as large as
25 cm (yes!) in diameter (Gould, 1969). The outer surface dried to a crust and in this state the
fruit could be stored indefinitely. The average nutrient analysis of all the dried AA fruits in
Table 1 (n = 7) shows that they are high in carbohydrate (59 %, v. 65 % in cultivated sultanas
and raisins), and contain moderate amounts of protein (8 %) and fat (4 %) depending on the
state of desiccation."

Further, my plan falls squarely in the estimates of macronutrient ranges of 229 hunter-gatherer diets by Cordain et al, i.e. 19-35% protein, 40-70% fat, 22-40% carbohydrate.

Don said...


Masai, Muhima, Watusi, and Neurs all kept cattle and ate mostly dairy products, not mostly meat. How does that resemble the Inuit diet composed mostly of meat? Milk and meat differ in important ways, such as milk contains far more calcium, milk is only slightly acid compared to meat (about 1.0 mEq per 100 g, vs 4.0-20.0 mEq per 100g for meats), milk supplies significant carbohydrate (2000 kcal of milk supplies 157 g carbohydrate, 2000 kcal of meat supplies 0 g). Moreover Price only provides data on dental disorders among them, not other diseases.

Price says of the Terraizeka: "These people are tall and live largely on fish and other animal life." This hardly describes a diet more like the Inuit than the !Kung. Living "largely" on animal products is very different from living almost exclusively on animal products. Price did not provide any evidence that they did not eat plant foods, and his use of the word "largely" indicates that they did use plant foods. Moreover, he provided no data on diseases among them, only data on dental decay.

Moreover, Price only checked developmental and dental health carefully. He did not directly study diseases associated with aging. A tribe could have great development and dental/oral health but suffer diseases of aging prematurely.

Don said...


The relative stability of modern species and high rate of extinction in the archaeological record lead me to conclude that most species do not have enough variability to positively adapt to large changes in the environment, which is why after 10K years of agriculture humans still have diseases found among the earliest agriculturalists but rare among H-Gs.

Moreover, as Lutz pointed out in Life Without Bread, grain cultivation produced increases in population size and greater opportunities to marry outside of geographically isolated groups, both of which act to slow down evolution (by reducing the opportunity for an individual to inherit the same characteristic from both parents), not speed it up. Thus, as modern ethnic groups intermarry, their evolved distinctness gets diluted in offspring (e.g. a Chinese and a Scot have children, which look neither Chinese nor Scottish). Isolation increases evolution, and agriculture decreases geographical isolation, bringing evolved ethnic groups into a "melting pot" that undoes evolution (I think, moving us back toward the !Kung, who have prototypical features of the major ethnic groups.)

Don said...


Oops! I wrote: "Wild types vary mostly by having higher contents of fiber and less sour or bitter secondary compounds."

But I meant: Wild types vary mostly by having higher contents of fiber and MORE sour or bitter secondary compounds.

Don said...


From Price's Nutrition and Physical Degeneration:

"Neurs, Malakal, Sudan. The Neurs at Malakal on the Nile River are a unique tribe because of their remarkable stature. Many of the women are six feet tall and the men range from six feet to seven and a half feet in height. Their food consists very largely of animal life of the Nile, dairy products, milk and blood from the herds.

A study of 1,268 teeth of thirty-nine individuals revealed only six teeth with dental caries, or 0.5 per cent. Only three individuals had caries, or 7.7 per cent.

Dinkas, Jebelein, Sudan. This tribe lives on the Nile. Its members are not as tall as the Neurs. They are physically better proportioned and have greater strength. They use fish from the Nile and cereals for their diet. They decorate their bodies profusely with scars.

An examination of 592 teeth of twenty-two individuals revealed only one tooth with caries, or 0.2 per cent."

Price thought that, compared to the Neurs, the Dinkas, cereal eaters, had better physiques and greater strength, and they apparently had less than half the incidence of caries. So if the Neurs had "remarkable health" what of the Dinkas, very unlike the Eskimos?

Miki said...

Thanks for the intriguing observations.
I am not sure that 'Equatorial' is as precise a definition as can be given to our common origin. I always think of a Serengeti type landscape when contemplating what type of nutrition our forefathers gathered and hunted. Most of the earliest sites of the Homo Sapience are centered around that area. There is a lot of grass in the Serengeti. I am not sure how easy it is to find fruits there but it sure looks easy to find a nice fat herbivore. Modern H+G like the Hdaza and the San have long been kicked out of the choice Savannah land so can probably not serve as a good model for evolutionary nutritional conditions.

Don said...


Evidence is not supporting a dry savannah origin for humans. Humans are poorly adapted to savannah ecosystems (we waste too much water). Early human remains are found in association with woodlands, lakes, rivers, wetlands, etc. As I reported in this post, bipedal hominids appear to have evolved in wet forests, not dry grasslands:

The savannah hypothesis has been dying for a long time...the archaeology does not support it. Nor does human anatomy and physiology, i.e. having very high water requirements, unlike savannah animals, we waste water...a very unlikely characteristic for an animal evolved in a dry environment.

Lee said...

"The question then arises, did Eskimos suffer any negative health consequences...".

Another question also comes to mind: do the San show ill-effects from the high consumption of omega 6 pufas from nuts? Amongst HG groups, I think they have the highest omega 6 intake whereas fish eating Eskimos have a high omega 3 intake. So in this respect, both these groups deviate from the HG norm and from what we may consider ideal.

Don said...


Mongongo nuts contain exceptionally large amounts of vitamin E, 565mg per 100 g. "Due to the very high y-tocopherol content, the oil is very stable, and doesn't oxidise into 'rancidity' for a very long time, in spite of the African heat."

I haven't heard of !Kung suffering any ill effects such as inflammatory diseases, heart disease, cancer. In fact, they would seem to contradict the idea that a high n-6 to n-3 ratio causes heart disease or cancer.

Why do you claim that large consumption of nuts deviates from the H-G norm? When was it established that prehistoric equatorial people did not eat large amounts of nuts?

Aborigines in Australia also consume large amounts of nuts, including varieties of candlenuts, walnuts, Almonds, oak seeds, and pine nuts.

I try to follow the evidence, not the narrative. Evidence indicates H-Gs exploited nuts when possible; and they didn't avoid those high in n-6 oils. So maybe we need to revise the n-6 story, not ignore the evidence.

Don said...

We could also question the high n-3 intake of Eskimos for adverse health effects (most likely prehistoric African hominins did not consume as much n-3 as Eskimos). Too much omega-3 can make the blood too thin. Eskimos have an elevated risk of hemorrhagic stroke and epilepsy compared to Danes.

PaleoDoc MD, PhD said...


I think this post is central to the whole "unified Paleo theory". I am not sure if acidity is that critical (within limits blood pH is easily adjusted through respiration), but the question of the true Paleo, the most natural diet composition is vital.

If you stick to DNA "hardware", then, indeed, you should look at African roots. But if evolution involves inheritance of acquited characteristics (I is heresy, but so is Paleo or even low-carb), then the story becomes more intersting. I wrote a bit about the possiblily of Lamarckian evolution here:
It might as well be that the Eskimo has plenty of time to methylate their DNA in response to environment and then pass the modified genes on. THere is no evidence, only speculation.

And since you are citing Lutz, his paper on spread of agriculture in Europe and its epidemiological consequances gives some insights:
The adaptation to Neolithic foods in Europe (and elsewhere) may have resulted not only from selection pressure, but also from inheritance of acquired traits.

It might as well be, that in herited late Paleolithic or early Neolithic adaptations are more important than original African genes. And it can be different in different people.

Don said...


Blood pH is adjusted via respiration and urination, but metabolic acid load occurs before adjustment. Further, the question is, does increased exposure to metabolic acids cause harm, especially if chronic? For example, do kidney tubules suffer damage from chronic exposure to excreted acid?

More in the next post.

Miki said...

Savannah is not a desert. Archaeological sites are indeed found mainly next to water bodies. The extinction of large animals in every corner of the earth from America to Tasmania soon after humans got there is evidence of the preference of humans to fat over any other macro-nutrients. Of course we ate nuts and fruits and may have been genetically or epigentically adapted to all sorts of foods, but they may all have been one big compromise, aimed at solving our inability to obtain fat.

Don said...


I didn't say that savannah is a desert, I said it is dry, compared to forest, wetlands, shores, etc.

Extinction of large animals might indicate human overhunting, and it might indicate other factors also like climate change.

Eskimos are the test case: Are humans, or even Inuit, well adapted to an Inuit-type diet? If so, they should have no diet related diseases, and conversely, H-Gs eating more plant foods should be less healthy than Inuit.

Don said...


Also, the human genome adapted to what people actually ate, not what they would have like to have eaten. So if limits on fat availability drove them to eat fruits and nuts, then they adapted to eating fruits and nuts and less fat. They adapted to waht they actually ate on a sustained basis, not what they would have preferred to eat or ate only intermittently.

O Primitivo said...

Hi Don. Here are some of my ideas regarding this acid-alkaline issue: "The reason the Paleodiet is NOT a Low-Carb diet" -

Don said...

O Primitivo,

Overall it looks like we agree, but not completely. Looks like you calculated that a paleo diet can't be net alkaline unless at least 33% CHO and not more than 42% fat. My example shows a diet with less CHO and more fat that is net alkaline. By choosing vegetables that have a low caloric and carbohydrate content, one could create a diet even higher in fat and lower in carbohydrate that still had a net alklaline ash. However, you can't create a ketogenic diet that has a net alkaline residue, which I think is the main point. And many low-carb people would say my 25% carb diet is not low carb, even though it has half the carbohydrate of a typical diet. Dogma.

O Primitivo said...

Hi Don, I suppose it all depends on the protein loads we consider. And there are many paleolithic diets, we can't define a single diet for all primitive humanity. I once produced a chart trying to ilustrate the acid-alkaline equilibrium as a function of carbs and protein load, see here: This graph is in portuguese (sorry for this) and it considers a typical 2700 kcal/day diet. For this ammount of calories, a ketogenic diet would be alcaline only for small protein intakes, perhaps up to only 60gr prot/day (or 300gr meat/fish perday).

Kaw said...

"However, you can't create a ketogenic diet that has a net alkaline residue, which I think is the main point. "

Is bone broth alkaline? Couldn't one use it to create a balanced ketogenic diet? If so, then it seems to me that the acidity of the meat can be reduced by adding bones to the cooking pot.

Mrs. Ed said...

Your series is very interesting. I am on the Specific Carbohydrate Diet for Crohn's and it's almost iliminated my son's autism. It is a grain free diet so I read a lot on paleo blogs because I can use most of the recipes and I now have a fascination with the relationship to food and health. I believe there is a strong connection to what we are evolved to eat and health/disease. Many paleo sites give the impression diet needs to be higher in meat. While I do need to eat meat each day and good fat, I've noticed that when I add a pile of veggies alongside it, I feel great. So I'm susupecting fruits and veggies may be just as important for optimal health.

I've seen so much conflicting info about which side of the ph coin is best, it may be awhile before I dare form an opinion on that one. But your posts do illustrate it a little better.

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