What About the Paleo Diet?
The Paleo diet (aka, the Caveman diet or the Stone Age diet) is very popular these days, esp. among the nutritionist/nutritional doctor community and there are lots of articles and books out promoting this way of eating as the healthiest.(1,2,3) We are told by supporters of the Paleo diet that we would do best if we ate a diet similar to the way that humans ate in the prehistoric Paleolithic period of human history. It is argued that our genes are adapted to eating this way and that in the last 10,000 years our genes have not changed much. According to S. Boyd Eaton, “Genetically our bodies are virtually the same as they were at the end of the Paleolithic era some 20,000 years ago.”(4) It is also argued that the modern diet of the last 10,000 years consisting largely of refined grains, processed plant foods, and domesticated animals is resulting in chronic diseases because we have not or can not adapt to this way of eating.
The diet of the hunter gatherers of the Paleolithic period is described by L. Cordain and others to consist largely of meat, seafood, fruits, vegetables, and nuts.(5,6) It is supposedly devoid of legumes (beans), grains, dairy, refined oils, refined sugar, and refined salt. It may or may not contain tree fruits. But is this really the case and is the Paleo diet really the healthiest one for us to follow?
While the Paleo diet writers correctly point out the relationship between our modern diet and chronic diseases, they are mistaken about what people ate in Paleolithic times and we have to some extent adapted to eating that includes foods raised by modern agricultural methods, though not necessarily changes that have occurred over the last 60 years, such as the loss of nutrients and the use of pesticides and other chemicals in food production methods. I argue that 1. Paleolithic humans did not eat exactly as it has been described by Eaton, Cordain, and others(1,2), 2. While our genes have not changed much, the expression of our genes (our epigenome) has changed and adapted to some of the modern agricultural changes, and finally, 3. an evolutionarily beneficial diet is one that allows humans to survive long enough to produce offspring, whereas most chronic diseases that afflict us today typically produce diseases, like heart disease and diabetes, that sicken and kill us in our older years. Therefore, the Paleo diet is more likely to be one that enables short term survival from starvation, etc. but is not necessarily going to prevent chronic diseases.
So what did the Paleo human eat?
Well, to begin with, you should consider that the evidence for what made up the Paleo diet is fairly limited and based on some big assumptions that may not be true, such as that an increasing skull size must have been caused by eating meat. Humans in the Paleolithic period ate what was available in the region in which they lived. This does not mean that this was necessarily the best diet to prevent chronic diseases. For example the iKung Bushmen of Botswana were hunter-gatherers who hunted, but the majority of their calories came from the Mongogongo nut, which is abundant and available year round, whereas they were only able to eat big game animals irregularly.(9) The Hazda of Tanzania used to eat lots of tubers (potatoes), because they were available.(10) The Greenland Eskimos, on the other hand survived on a diet largely consisting of whale and seal meat.(11) This doesn’t mean that we should all start eating lots of Mongogongo nuts or lots of potatoes (tubers) or whale meat? No, of course not. We may be motivated today to eat in a way that will make us look and feel our best and prevent heart attacks and cancer, but these hunter-gatherers were motivated by their survival instinct, which meant that they needed to eat whatever was available to give them enough calories to stay alive. They needed to avoid starvation. Unfortunately, those same survival instincts lead our bodies to store fat in case we don’t have enough food in the future.
Some recent evidence indicates that humans in the Paleo period apparently did eat a certain amount of grains and tubers, contrary to the Paleo diet claims. Even though today we grow wheat and other grains in places where it might not grow naturally, grains like wheat do grow naturally in some regions of the world and it is likely that prehistoric humans would have eaten them. They may not have been able to process them into Twinkies, but they likely found some way to process them enough to consume them. And some evidence exists of sorghum starch grains having been consumed by Paleolithic humans from the surface of various grinding tools found in a cave in Mozambique from at least 30,000 years ago.(7) So, apparently, grains like sorghum were a part of the diet for humans even in the Paleo period. And Africans today mill sorghum and eat it as porridge, baked goods, and as beer. Likewise, there is evidence that prehistoric humans ate certain naturally growing tubers (potatoes).
The expression of our genes has changed
There is reason to believe that our bodies have adapted to a more modern diet involving agriculture and animal husbandry. Our genes may be the same or very similar to the genes of Paleolithic humans, but the epigenetic expression of our genes has changed significantly. Our genes have become epigenetically modified to adopt to a more industrialized diet. According to Dr. Jeffrey Bland, “We no longer respond to our environment in the same way our Paleolithic ancestors did. In fact, it is highly likely that Paleolithic humans could no more easily accommodate the metabolic challenges of the 21st century than we could accommodate the environment of our Paleolithic ancestors.”(8)
Evolution would not select out a diet that causes chronic diseases
Evolution would lead to a diet that enables humans to survive and starvation has traditionally for thousands of years been the biggest threat to our survival, not chronic diseases. For rich countries like the United States, starvation is rare and chronic diseases are our biggest worry. In caveman times, humans needed to eat enough calories to survive long enough to give birth and see that their offspring survived into adolescence. Eating some animals when available with their high fat content (that contains 9 calories per gram, compared to 4 calories for carbs and proteins) would provide enough calories to survive until enough edible plants could be found. Mongo mongo nuts provided the dense calories that enabled the iKung Bushmen to survive in between catching wild animals. What was important was to ingest enough calories to survive and this is what drove humans to eat what they did.
Therefore, if the Paleolithic diet is not the diet that will prevent the chronic diseases that our the biggest threat to our living a long, happy life in the modern world, then what is? Well, that is the topic of a future post, but the short answer is a low glycemic, Mediterranean style program for most. I will show in a future article that this is the diet that is supported by the most research. You could view this as a modified Paleo diet that also includes legumes (beans), a limited amount of whole grains, some healthy processed oils such as olive oil, and perhaps some limited dairy, such as yogurt. From my understanding of the research, the Paleo diet involves consuming too much meat and animal fat to be associated with optimal health. On the other hand, I agree with the emphasis that the Paleo diet places on avoiding overly refined and processed grains, sugar, and other foods common in our modern lifestyle that likely lead to chronic diseases, like diabetes, heart disease, and cancer.
References:
1. Eaton SB, Shostak M, Konner M. (1988). The Paleolithic Prescription: A Program of Diet & Exercise and a Design for Living. New York: Harper & Row.
2. Cordain, Loren (2002). The Paleo Diet: Lose Weight and Get Healthy by Eating the Food You Were Designed to Eat. New York:Wiley.
3. Lindeberg, Staffan (2010). Food and Western Disease: Health and Nutrition from an Evolutionary Perspective. Chichester, U.K.:Wiley-Blackwell.
4. Eaton SB, Eaton SB 3rd, Konner MJ. Paleolithic nutrition revisited: a twelve year retrospective on its nature and implications. European Journal of Clinical Nutrition. 1997; 51: 207–16.
http://www.nature.com/ejcn/journal/v51/n4/pdf/1600389a.pdf
5. http://thepaleodiet.com/paleo-diet-faq/
6. Carrera-Bastos P, Fontes Villalba M, O’Keefe JH, Lindeberg S, Cordain L. The western diet and lifestyle and diseases of civilization. Res Rep Clin Cardiol 2011; 2: 215-235.
7. http://www.cbc.ca/news/technology/story/2009/12/17/tech-archaeology-grain-africa-cave.html
8. Bland J. Epigenetics: the death of the paleolithic human? Integrative Medicine 2006; (5) 4: 10-12.
9. http://artsci.wustl.edu/~anthro/articles/lee_1968_1.pdf
10. http://www.bioanth.cam.ac.uk/fwm23/tubers_and_fallback_foods_21040_ftp.pdf
11. Bang HO, Dyerberg J, Sinclair HM. The composition of the Eskimo food in north western Greenland. Am J Clin Nutr. 1980. 33: 2657-2661.
***Check out the brilliant TED talk by Christina Warinner, who is an archeological scientist, who debunks much of the Paleo diet: http://www.youtube.com/watch?v=BMOjVYgYaG8
3Christina Warinner
