Saturday, April 30, 2011

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. 


26 comments:

Tuck said...

"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."

It's likely that humans were the cause of extinction of the largest, fattest game animals, what's becoming known as the anthropocene exitinction, or man-caused. These extinctions followed man-kind around the world.

This started 50,000 years ago, long before the end of the paleolithic.

Prof. Dan Lieberman's running man hypothesis easily explains how mankind was the dominant predator on Africa, and then the world, for 2+ million years. The required technology was evolved, not invented. I'd call that the "main part of human evolution".

But's it's the paleo community is pretty wedded in general to the notion that running is bad for you, so it's not too surprising to find a blind spot here.

This does sort of undercut the thrust of their argument, however.

I'll stick with the humans are meat-eaters hypothesis, as it seems to me to have stronger evidence (unique human adaptations to running, the extinction of large land mammals as humans spread around the planet, and a clear historical record of humans being able to run animals to death, leaving them in a state where they can be strangled by hand.)

tpasssin said...

I have a few comments that bear on what you report above.

1) I've read that large cats (lions, cheetahs) have a fairly low kill success rate, lower than the 30% figure mentioned. Yet they are carnivores. So a low hunt success rate doesn't by itself mean that a creature primarily lives on non-meat.

2) Humans have pretty clearly evolved to de-emphasize plant food - based on their reduced intestinal tract and teeth. Yet the fact that humans can still detoxify many plant toxins suggests that plants must have remained a significant part of the human diet. That leaves us with being omnivorous (which we know anyhow), but possibly leaning more heavily on the animal side.

Don said...

Tuck,

The possible anthropocene extinction took place after humans discovered cliff-killing. Its surely not a result of running down individual animals.

!Kung do some persistence hunting, but on average, about half of their calories come from plants. Evolving adaptations to eating meat does not eliminate adaptations to eating plants.

I can just envision humans strangling hippos, mammoths, etc.

I certainly didn't say, nor does this paper say, that humans are not meat-eaters. Omnivores are meat eaters, fish eaters are meat eaters.

I'd say that the evidence that long distance running can do a lot of harm is pretty strong.

Don said...

tpassin,

the fact is, most observed human foraging groups get a substantial amount of their energy from plant food, on average 50%. So the fact that lions live only on meat, or even that some human groups live or have lived almost exclusively on meat, doesn't tell us how much plant food hominins ate during the evolutionary period when the adaptations to hunting were in development.

And, we obviously still retain adaptations to plant food foraging, the most prominent being color vision. Obligate carnivores have sharp sense of smell but don't need color vision to find food...for them, if it moves, it is food.

But plant eating animals benefit from color vision because it helps distinguish between ripe and unripe.

This just illustrates that we come from ancestry that at some point was dedicated to finding ripe fruits and vegetation for food, and we still retain some of the important equipment for the tasks of plant eating: amylase enzyme (starch-digesting), sucrase enzyme (sugar digesting), haustrated intestines, color vision, manual dexterity (picking, peeling, de-seeding), all things we share with plant-eating apes.

That doesn't mean we're designed to be raw vegans. But many people do feel a benefit from plant-based diets, for a time, and research shows them beneficial, for a time.

So, is there a middle ground? Let's see.

Rudolf Wegener said...

Is anyone thinking about how many insects they ate?
Insects should be pretty easy to "hunt" and are rather nutritous.

kulimai said...

This is all very interesting and I'm very much looking forward to the rest. But I think for the discussion to be really useful, in this domain in particular one needs to distinguish more clearly the notion of optimal for health(span) and that of optimal for reproductive survival, -related but clearly distinct concepts.

To take an example when Don says above that running is bad for health(span) that has to do with the former so not directly relevant without further supporting argumentation to the question of what the result of selection for reproductive survival was. (I'm talking here about the logic of the issue, not of its substance.)

Jenna said...

I think this is such a smart post. I think more Nutritional Scientists, need a touch more humility before proclaiming the benefit of one eating lifestyle over another. We still know very little, and Nutrition seems highly individualized. So, bravo, bravo to your writing! I've just quite "Paleo". I think I will stick to variety, for the future, as new studies come in.

Ed said...

I like the term "mesonutrients" for fatty acids, glucose vs fructose (and starch vs oligosaccharides), and amino acid composition.

Chuck said...

Thank you for this analysis. I too have come to the same conclusion lately despite not reading this paper. I read the book Catching Fire and have started to realize plant foods are a staple and meats are a luxury. It seems that plants are for sustenance and meats are for growth. Every hunter gather society craves meat and hopes for it on a constant basis but they don't get it every day for every meal. Plants seem to be that constant.

soiltosustenance said...

"I'd say that the evidence that long distance running can do a lot of harm is pretty strong."

Agreed; however when I read "Born to Run" and the papers by Lieberman, my reaction wasn't that persistence hunting meant long distance running in the mode of modern day marathoners. Rather it looked to me like lots of sprinting and resting (stalking and tracking). And with some better hunting strategies (larger hunting parties perhaps), it seems like an individual would have even greater opportunity to alternate periods of intense effort with rest.

...Tim

Shel said...

this really jives with my experience. i thrive only when i sustain on mostly greens and fruits (sweet and non-), and some cooked starchy tubers (yam, sweet potatoes, taro, cassava) each day; then the occasional meat binge with a load of fat when i crave, and a very occasional binge on nuts.

hopefully the paleo movement is growing up and becoming lucid.

falsification kills dogmatism; i think many supposed "lights" in this community would do well to remember this.

thanks Don. you seem to be less prone to hubris (and even emotionalism!) than some others.

Don said...

Shel,

Thanks. I try to stay aware to 'black swans' to keep myself from dogmatism. Not always successful in the moment, but I think over the long run I tend to self-correct. Sometimes its embarrassing to have to publicly correct myself, but I value integrity above all.

Jenny Light said...

I second the comment by Rudolf. Insects, worms, grubs etc are very high in protein and seem to be consumed by modern hunter-gatherers on an almost daily basis.

Ever watch "Bizarre Foods with Andrew Zimmern" or any of those tribal shows? Easy to catch and eat. Many of the animals were huge during the Paleolithic and the bugs probably were too!

David said...

when i visit my friends up in northern Thailand insects are always on the menu. From tiny red ants to large flying beetles, easy to catch, tasty to eat ( once habituated) and such a variety!

Sue said...

No I don't think it's embarrassing to publicly correct yourself. It shows that you are willing to change your beliefs when presented with evidence. That's the way it should be. It reminds me that I need to change my email address to reflect my recent slackening of strict carb restriction.

Khwarezmian said...

East Asians have a higher IQ because of genetics, not because of diet. Their IQ advantage over whites is preserved even in immigrant populations that have switched to the SAD.

Stephan Guyenet said...

I don't understand how they got their incredibly high omega-3 estimates in that paper. I don't understand how they would have gotten 17-35g of omega-3 per day. I haven't discussed the paper because certain elements of it strike me as hard to swallow.

Don said...

Khwarezmian,

Do you have any research backing that assertion that Asians are genetically higher IQ than other ethnic groups? I am inclined not to accept it for the simple reason that all of the top five are wealthy Asian nations who have excellent nutrition, whereas Asians in less wealthy nations (and poorer nutrition) have much lower average IQs, for example China ranks #12 and Thailand #40.
Also, all of the high ranked nations have high fish intake supplying DHA a neural fatty acid, and in Japan they value it so much that they habitually enrich foods with DHA.

Also, when people move to the U.S. they don't generally completely abandon their ethnic ways of eating. Italians continue to eat Italian food, Germans German food, and Asians, Asian food...they probably eat even better (more fish) when they get to the U.S. since they have more funds. We have a few Asian grocery stores here in Phoenix, and they sell plenty of fish to their mostly Asian customers, of all ages by my estimate (I shop at those stores for some things).

Don said...

Stephan,

I'm going to address that. I've contacted Cordain for clarification.

Shel said...

~Don

don't be at all embarrassed. i had to eat crow (so to speak) when my meat based, high fat diet nearly sent me into a nervous breakdown due to anxiety (cortisol? adrenaline?).

...and yes, good science never tries to "prove" anything; rather, it tries to deconstruct, break down, and disprove. if a theory can't be falsified, it becomes stronger, but is never "settled" (like the "settled science" of climate change. grrr...)

but i rant. heh...

skylertanner.com said...

It's interesting the discussion of plant vs. animal. I had asked Robb Wolf about my love, love, LOVE of almonds. If I don't exercise control, I could put down a pound of these everyday. While the n-6 load is enough to make Kurt Harris cry, I feel good, perform well, am lean etc. etc.

It's my understanding that !kung live on a very large quantity of mongongo nuts. I cannot find any papers from a quick google search regarding their health but it seems like they're quite robust. Perhaps you have more info in this regard?

Best,
Skyler

Don said...

Skyler,

I had a discussion about this with Stephan a while back. Yes, the !Kung eat a lot of Mongongos and get a lot of n-6 from them. They have no cardiovascular disease and generally good health. Wild game also has a higher n-6 linoleic acid content. I think n-6 is most hazardous when consumed in extracted, purified, commercial oils. Nuts have many other components that protect and counterbalance the negative effects of isolated n-6. Whole foods have effects different from isolated refined nutrients e.g. vegetable oils.

Paolo said...

When we compare diets we should also consider the climate and the amount of sun a population is able to get.

Maybe the Inuit have higher osteoporosis because they lack Vitamin D, that they desperately try to get from food. I don't think they could survive eating the diet of the Kitavans.

Mosaic said...

I find it rather absurd to characterize the diets of early populations as being predominately one food over another. The fact of the matter is, these people were opportunistic eaters. They ate everything in sight and seldom had the luxury of choice between a Woolly Mammoth al fresco or a Caesar Salad sans Croutons. They typically were in constant starvation mode, during which the body accumulates fat as a survival mechanism, resulting in the grotesque statuette depicted. Fat people back then were survivors, not too self conscious about weight gain and certainly not selective in the food they had to find and eat. The last thing on their mind was making the cover of Elle Magazine. So whether their diet was 22.63466% meat or 53.7299% plant is totally irrelevant to the fact that shoveling food into their pie hole was priority number one for the day.

Don said...

Mosaic,

If the body accumulates fat when in "starvation mode" then how do you explain the fact that people starved in concentration camps get emaciated? Why are anorexics thin?

So far as I know, no one has ever shown any one getting fat via starvation (energy intake way below energy output). Starvation mode causing people to get fat is a myth. If you disagree, I invite you to take some before photos, starve yourself for a month or two (say, eat no more than 200 calories daily) and then take after photos and show everyone how much fat you gained.

People only get fat by having a constant supply and intake of food energy exceeding their energy expenditure. This imbalance comes about by overconsumption or low expenditure or a combination of the two. You can argue (a la Taubes) that this results from an excess of insulin. It may also result from an under production of thyroid hormone, excessive fat intake, disruption of circadian rhythms, or loss of muscle tissue, and probably other causes.

Alan said...

Pemmican enthusiasts claim that the Plains indians were rendering the fat of buffalo.

To be fair, they may have started doing it after the Spaniards introduced them to pottery. After all, they picked up on horseback skills (also introduced by Europeans) intuitively.

But that's what h. sapiens sapiens evolved to do.... learn fast!