Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet: Part 1

I haven’t seen any primal/paleo bloggers discuss this paper written by seven leaders in paleo diet research: Remko S. Kuipers, Martine F. Luxwolda, D. A. Janneke Dijck-Brouwer, and Frits A. J. Muskiet  from University of Groningen, the Netherlands; S. Boyd Eaton (co-author of The Paleolithic Prescription), Loren Cordain (The Paleo Diet), and Michael Crawford, co-author of Nutrition and Evolution (one of my favorite books on evolutionary nutrition).

I think that might be because the data given in and conclusions made by the authors of this article don’t necessarily or strongly support the dietary direction that the popular primal community has taken.

Using a database of the nutritional composition of wild, predominantly East African foods, the team estimated the macronutrient and fatty acid profile of multiple possible Paleolithic diets.  They created all models based on the most common known hunter-gatherer plant/animal subsistence ratios, ranging from 30% of energy from plants and 70% of energy from animal products, to 70% of energy from plants and 30% of energy from animal products. 

The team excluded the possibility of evolutionary diets consisting of more than 70% of energy from animal foods for two main reasons.  First, during the main part of human evolution our ancestors did not have the technology required for hunting the largest, fattest game animals, or being top carnivores, and more likely depended on scavenging for most land animal meat.  Scavenging does not often supply large amounts of meat or fat simply because obligate carnivores eat those parts before humans get to them (something I will discuss in the next post).  Secondly, as they put it:

“….in contrast to common belief, hunting probably played a less dominant role from a nutritional point of view compared with gathering, and on average, it makes up 35% of the subsistence base for present-day worldwide hunter–gatherers, independent of latitude or environment (27,37). For example, hunting by some surviving hunter–gatherers is still not very successful: the probability for a kill in !Kung bushmen is only 23% (37), and the subsistence of Hadzabe, as described by Woodburn (39), consists of 80% plant foods. In the Paleolithic, however, hunting might have been more productive, due to both higher animal biomass and hunter–gatherers not being displaced to marginal environments, unattractive for crop cultivation or cattle.”

In other words, despite having more advanced technology than had by human ancestors 100, 000 years ago, modern hunter-gatherers typically do not obtain more than 35% of their food from hunting.  Thus, the authors are actually quite generous in allowing for the small possibility that ancient people (prior to 50, 000 years ago) obtained twice as much of their food from animals as do current hunter-gatherers. 

This perspective may cast doubt on the currently popular idea among primal/paleo bloggers, in which I myself have gotten a bit caught up, that modern humans are primarily adapted to a diet consisting almost entirely of land animal meat, particularly fatty meats, with little or no adaptation to plants: anti-vegan, as some have put it.   It may even suggest that the primal human diet contained more plants than animal products (though certainly omnivorous), or perhaps more fish than meat. 

I have the impression that the Kitavans have better health and longevity, on average, than Inuit.  For example, Kitavans have no recorded osteoporosis, which appears to have occurred among isolated Inuit (see here and here). Could this suggest that, compared to the Inuit diet,  the Kitavan diet more closely resembles the ancestral African diet? 

Also, Japanese, particularly Okinawans, and residents of Hong Kong, have better health and longevity, on average, than any other modern nation, due largely to lower rates of obesity, cardiovascular disease, cancer, and dementia.  Further, looking at international comparisons of average IQ, the top five nations are:

1) Hong Kong
2) South Korea
3) Japan
4) Taiwan
5) Singapore 

Could this suggest that, compared to the Austrian, German, Italian, or Swedish diets, in terms of brain nutrition, these Asian diets more closely resemble the ancestral African diet?  Would that make sense?  That would certainly shake things up, eh? 

Or, perhaps during the main part of human evolution, our ancestors on average ate something in between the extremes of the Inuit and the Kitavan diets, thus producing an animal primarily adapted to a mixed paleofoods diet, that also can adapt, with variable success, to both extremes.  Would that make sense?  Let's see. 

In producing their estimates, the team left out of their final estimates any model that either 1) supplied more than 35% of energy from protein, because such a diet followed long term would cause protein poisoning, or 2) supplied less than 1% of energy from linoleic acid, because such a diet would lead to essential fatty acid deficiency that would likely impair reproductive fitness. 

They did all calculations assuming ‘optimal foraging,’ i.e. people choosing more energy-rich over less energy-rich foods whenever possible.  In their calculations, they varied the fat contents (measured by weight, i.e. g/100g) of plants from 2.5 to 5.0% fat, of meat from 5.0 to 30%, and of fish from 2.5 to 10%.   Meat that has a 30% fat content by weight (30g fat per 100g meat) has a fat:protein ratio equivalent to bacon or sausages.

Their basic models included foraging in either a savannah, a land-water ecosystem, or both.   Each model had carefully chosen and justified parameters.  I will discuss these in my next post.