Opening Comments

In keeping with the theme of evolution and nutrition, today’s article is going to be the first installment of a two-part series on the Paleo diet (also called hunter-gatherer, Stone-Age, or ancestral dieting). Even if you are not familiar with Paleolithic nutrition per se, you most likely are familiar with Atkins, The Zone, or South Beach, which are essentially less-strict versions of ancestral eating. However, given their differences, we won’t concern ourselves with them and will therefore just stick to looking at Paleo.  Part 1 will solely place emphasis on the Paleo diet and some of the inherent biases/contradictions it contains. Part 2 will strictly be reserved for a research review on the literature supporting the Paleo diet, wherein I will make some final comments and sum things up. My goal for today is to show you all why Paleo is a flawed and inflexible diet system comprised of ideologues who cement themselves in assumptions while blindly disregarding scientific literature that opposes their own views about nutrition. So, without further ado, let’s begin by taking a look at what Paleolithic nutrition actually is.

Enter Paleo: Society’s Stone-Age Solution  

In essence, the Paleolithic period – some 2-million years ago – marked the start of humanity, most notably, with the advent of stone tools in order to facilitate food consumption. During this time period, it is assumed that grain and sugar consumption (other than fruit) was virtually nonexistent, maybe except for occasional honey here and there. Taking this into account, Paleo dieters believe that the Paleolithic “style” of eating – i.e. a diet devoid of grains, starches, sugar and dairy – is best suited to our current genetics because we have changed little – if at all – since the emergence of agriculture and its products some 5,000-10,000 years ago. To quote Dr. Loren Cordain – “the world’s leading expert on Paleolithic diets” – directly from his book, The Paleo Diet:

“Literally, we are Stone Agers living in the Space Age; our dietary needs are the same as theirs. “

It is from this rationale that Paleo fanatics believe that obesity, diabetes and the other “diseases of civilization” are caused from the consumption of grains – or as they like to call them, “the double-edge sword of humanity” – because these diseases were not a problem back then when grains were unavailable. However, today, both an overabundance of grains and diseases are available. Therefore, no post-agricultural foods are to be consumed because they somehow contradict our genetic disposition. As extremist as this is, many people are taken in by this philosophy because it does offer a very logical explanation for the current health crisis we are now witnessing. What most Paleo nuts choose toforget is that we also did not evolve with television, computer, cars, etc. that lowers our energy expenditure and potentially leads to weight gain and certain diseases when combined with poor dietary habits. Yet, most of them continue to use these things on a daily basis; hypocrisy? I’ll let you decide. That’s another article for another time; today’s focus is strictly nutrition.

Now, I have to say that I am in agreement with the idea that a diet which is full of McDonald’s, Dunkin’ Donuts, and other processed foods is not the healthiest diet to consume; no argument there. However, if you’re trying to debate that oatmeal, milk and a little bit of sugar here and there are bad for me, then Ihave a problem. But, before I get ahead of myself, let’s see if we can actually quantify what a “caveman” actually ate all those years back.

What did a Caveman Actually Eat?

In a few words: we can’t be sure and probably never will. However, even crazier than the people themselves are their claims that they, the Paleo proponents, actually know what a caveman ate. In one of the first papers talking explicitly about Paleolithic nutrition, authors Eaton and Konner provided some general ranges for the types of food sources a person might have eaten back then based off of some more recent hunter-gatherer societies which lasted into the late 20^th Century [1]. Although this serves as a rough estimate for Paleolithic nutrition, one must keep in mind that a hunter-gatherer culture living in the 1960’s is extremely different from that of a Paleolithic society living hundreds of thousands of years ago. Any suppositions made from these observations are purely speculative and far from conclusive. Nevertheless, using these contemporary hunter-gatherer societies (living mainly inland and in semi-tropical climates), Eaton and Konner saw that anywhere from 20-50% of their diet was obtained from meat and anywhere from 50-80% of their diet came from vegetation. However, populations in artic regions – like that of the Eskimos – derive as little as 10% of their diet from plant-based sources. Therefore, if my calculations serve me right, the ranges of nutrients potentially run anywhere from 20-90% meat-based and anywhere from 10-80% plant-based. To me it seems as though there was not one single hunter-gatherer-type diet. In fact, a well-written review by evolutionary archaeologist, John Gowlett [2], argues that in no way there could have been only one “Stone-Age diet.” This is due to various geographical limitations, such as food variety and climactic changes, which would require various nutritional adaptations to be undertaken in order to survive in a given region. Therefore it can be determined that humans did not evolve eating any one type of diet, but rather an all-encompassing and extremely varied diet that would allow for adaptive survival given their geographic location/conditions. This is exactly what was seen in our more recent hunter-gatherer proxies. But does that stop the Paleo zealots from prescribing strict nutritional guidelines?

Paleo’s Take on Hunter-gatherer Nutrition

Led by Dr. Loren Cordain – who, to his credit is published in a multitude of peer-reviewed journals – the Paleo diet is characterized by two food-lists; foods you can/should eat, and foods you should avoid at all costs (lest you not fear for your own health and well-being). Boiling it down even further, foods to consume and avoid are provided below, along with picture for those who are visually inclined.

You’ll notice they have a pretty rigid set of dietary guidelines. Furthermore, if you’ve ever read Cordain’s book (The Paleo Diet), you would have noticed some percentages for protein, carbs and fats (pg. 11) . In fact, they all fall well within the ranges noted earlier. However, like I already mentioned, we don’t know what a caveman ate! Providing your own dietary ratios for macronutrients is nothing more than using a blank slate with which to project your own views about diet composition. Disobey these dietary dogmas and I assume it’s like Scott Pilgrim vs. the World when the Vegan Police come and take Todd’s vegan powers after drinking a latte made with half and half. Well, maybe not that bad, but you’d probably be ostracized on some level.

Now, it’s pretty obvious that grains are to be wholly excluded from the diet. Again, this is due to the fact that grains were not (presumed to be) consumed prior to the agricultural revolution some 10,000 years ago. However, in 2009 and 2010, two papers were published that showed grains were indeed part of Paleolithic nutrition some 30,000 years ago [3], going as far back as 105,000 years ago [4]. To quote one of the authors directly [4];

“A large assembly of starch granules has been retrieved from the surfaces of Middle Stone Age tools from Mozambique, showing that early Homo Sapiens relied on grass seeds starting at least 105,000 years ago, including those of sorghum grasses.”

Even if you believe that 10,000 years is not enough time for genetic adaptation to occur, it would be hard to argue that 105,000 years isn’t either. Not only do these findings undermine the diet’s protocols, but they also illuminate the inherent weaknesses contained within the diet prescription itself: Paleo dieters have no idea what a Paleolithic man ate! Therefore, one cannot prescribe a diet based on assumptions that are not fully substantiated in scientific literature. Otherwise, as I already stated, you are using a blank slate with which to project your own ideological views about nutrition. Another perfect example of this is Cordain’s other book, The Paleo Diet for Athletes. To quote the text directly:

“Perhaps the most important refinement made to my original Paleo Diet was [the] recognition that consumption of starches and simple sugars was necessary and useful only during exercise and the immediate post-exercise period.” (pg. 6)

So wait, now Cordaine is advocating for starch and sugar consumption? Even when his entire manifesto was built around the notion that grains and starches are evil and should never be consumed? As you can see, Paleo fanatics make exceptions only where they see fit, all the while still calling it Paleo, even when it deviates from their core principles. I like to call it Paleo Plus! All the benefits of Paleo, plus the benefits of the things they say we’re not biologically meant to consume. You truly can have your cake and eat it too! Not that they would…

It’s not ALL bad, though

Now that we’ve pointed out a few of the biases and contradictions contained within the diet’s ideology, I think it’s only fair to point out some of the benefits that a Paleo diet can offer…and then some of the benefits from foods Paleo dieters choose to avoid. You didn’t think I would let them off the hook that easily did you? Nothing Paleo zealots do make any logical sense.

Benefits of the Paleo Diet

Based on what we just saw, going Paleo primarily consists of lean meats, seafood (with an emphasis on omega-3s), fruits, vegetables, and various nuts and seeds which also contain some “heart-healthy” fats. As a nutrition student, I would be lying if I said I disliked any diet that advocated for such a healthful array of foods. In fact, the scientific literature supporting the benefits of said food types runs the gamut. Fruit and vegetable consumption is consistently associated with reduced risk of coronary heart disease [5, 6], stroke [7, 8], type II diabetes [9, 10], and even some types of cancers [11-14]. Similarly, omega-3 consumption (either via supplementation or fatty-fish consumption) has been shown to reduce certain cardio-metabolic risk factors [15] as well as incidences of many chronic inflammatory diseases such as IBD, cancer, rheumatoid arthritis and Alzheimer’s [16]. There is even starting to be some strong evidence for the use of omega-3s, specifically EPA, in the treatment of depression [17]. Lastly, nuts have been implicated in the improvement of cholesterol levels, oxidative stress, blood pressure, inflammation and other cardiovascular risk factors [18, 19]. Ideology aside, the literature seems to support the basis of Paleo, but what about the foods they don’t consume?

Paleo Dieters are Missing Out!

Although the foundation of Paleo is bolstered by scientific literature that confirms the plethora of health benefits to be expected when one eats fruits, vegetables, nuts and lean sources of meat, what the Paleo extremists seem to be flat-out ignoring are the health benefits from foods they’re excluding – nay, unjustifiably denouncing!

Benefits of Paleo-banned foods

In the interest of time I’ll stick to the major food groups noted on the ‘avoid’ side of the above Paleo manifesto, those being grains, legumes, and dairy. Starting with grains and legumes, whole grains have been associated with having protective effects against the development of type 2 diabetes [20], coronary heart disease [21, 22], and stroke [22] while both are associated with improvements in glucose, lipid and lipoprotein metabolism in both healthy and diabetic populations [20]. Furthermore, in a recently published review looking at 135 studies on refined grains – namely breads, pastas, rice and cereals – it was shown that there was no association between refined grain consumption and an increase in disease risk, even when 50% of grain consumption came from refined grain products [23]. So, at the very worst, there’s no ill effect of refined grain consumption, as long as it doesn’t comprise the majority of your diet. At best, you get all of the above-mentioned health benefits from whole-grains and legumes. Paleo zealots, however, just look the other way.

Dairy is the next food group exiled on account of its relatively recent inception. Dairy products weren’t introduced until about 5,000 years ago, which is, according to Paleo dieters, well-after human evolution (as if it were some event in time rather than a fluid process which still continues to this day). Therefore, dairy is denounced just the same—that is, unless you’re former NFL lineman, John Welbourn or Paleo advocate and author, Robb White, who both follow a Paleo + Dairy regimen (or as Alan Aragon so eloquently put it, “A Paleo-when-convenient doctrine.”) Regardless of individual inconsistencies, the Paleo dogma clearly states which side of the isle it’s on with complete disregard to evidence pointing the other way. For instance, dairy has been shown time and time again to be a major factor in the maintenance of bone health due to the ample amounts of protein, calcium and other minerals present in milk that help regulate and comprise human bone [24-27]. To quote a recent study on dairy [28];

“[Al]though it is possible to meet calcium intake recommendations without consuming dairy foods, calcium replacement foods are not a nutritionally equivalent substitute for dairy foods and consumption of a calcium-equivalent amount of some non-dairy foods is unrealistic.”

In fact, a study—which we will look at next week—that compared a Paleo diet to a traditional diabetic diet saw that calcium was significantly lower (~50% less) in the group adhering to a Paleolithic diet [29]. Furthermore, there has been accumulating data to suggest that dietary calcium further improves weight loss/management [30-32] and is responsible for up to 50% of the anti-obesity effects of dairy [32].

Those seeking to add muscle would most certainly benefit from the consumption of dairy products due to its shown effects on strength and muscle gains when combined with resistance training [33-37]. Moreover, a fractional component of milk protein, whey, is commonly used in supplements and has been shown to enhance muscle hypertrophy and recovery from heavy lifting, as well as decreasing muscle damage and soreness [38]. It has even been argued to be the “ideal” protein source for stimulating muscle protein synthesis [39]. Lastly, whey protein is even implicated as also having anti-obesity effects, complementing those of calcium [32]. This, in part, seems to be due to the high content of the amino acid Leucine seen in whey protein. Obviously a good case can be made for not adhering to a Paleo diet due to the quantitative benefits offered by the foods that are not eaten – in reality, decried – by Paleo dieters.

Summary

So, as you can see, there are some pretty stark contradictions within the Paleo way of eating. Not only do Paleo advocates follow a rigid diet based on loose assumptions of ancestral food patterns (which they’re wrong about in the first place), but they also make adjustments to their philosophy where they see fit, even if it deviates from their core principles. To me it just sounds like an excuse to impose one’s own views about nutrition on others. Next week we’ll take actually take a look at some studies that support Paleo diets and see whether or not Paleo lives up to all the hype, regardless of how flawed its ideology is. So until then, keep enjoying your oatmeal and protein shakes. I sure know I will!

References

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4. Mercader J. Mozambican grass seed consumption during the middle stone age. Science 2009;326:1680-1683.

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