The Dairy Question and The Paleo Diet’s Epistemic Continuum

Dairy has a peculiar status among Paleo eaters. Although it’s a Neolithic food, it’s usually considered healthful if one is not lactose intolerant. Recently, I have been struggling with it’s acceptance, for a couple of reasons, and it’s helped elucidate an interesting difference among members of Paleo community.

The most important concern of mine is the difference between acute effects and chronic effects. That is, something that may show no distinguishable harm in the short-term may end up causing harm after decades of consumption. Discovering an effect like this is very difficult, because it’s impossible to do a well-controlled study of long-term nutritional effects in humans, and if your working theory is that something may be harmful, it may also be unethical to attempt such research. Epidemiological studies are the best science can offer, and we’re all familiar with their weaknesses.

Specifically about dairy, it’s been shown to have unique biochemical effects in humans. Several vegetarian diet advocates claim that dairy is addictive, based on the research that it contains peptides that bind to opioid receptors.[1] Effects like this may be suitable for a calf to help it quickly gain body mass, but we certainly don’t need any extra encouragement to eat. I should note that I can’t find any scientific literature that makes the specific claim that dairy is addictive.

More fundamentally, cow’s milk has evolved to feed rapidly growing cows, not humans. As a result, it carries several hormonal effects that may be unsuitable for humans.

On a different note, it seems that dairy has gotten in through the back door, because it’s a low-carb/high-fat food, and for many Paleo eaters, Paleo is just a cleaned-up low-carb diet. But not all fats are OK, as we’re all aware of the trouble with Linoleic Acid.[2] Dairy doesn’t deserve acceptance for being a low-carb food.

I’m lactose intolerant, so of course that colors my view of dairy. Perhaps there is more to this story that I am missing, but it seems best to avoid dairy altogether and eat mostly ancient foods like meat, organs, vegetables, and fruit, regardless of one’s short-term lactose tolerance.

This choice illustrates where one is on the Paleo diet’s epistemic continuum–a concept that explains the differing food choices we make, all under the umbrella term “Paleo.” On one end of the continuum is nutritional science that lacks theoretical underpinnings, and on the other end is relatively unsupported evolutionary theory (the middle is where science and evolutionary theory agree). How do we decide which direction to head when nutritional science and  evolutionary logic/anthropology seemingly conflict?

Most of the time, we have science on our side; well-controlled, randomized studies can be cited to defend a fair amount of the Paleo platform. But sometimes things get messy. The Dairy Question is a prime example. In a way, the continuum has helped explain the various flavors of Paleo. On one end of the continuum, Dr. Cordain and Robb Wolf tend to favor evolution and anthropology when it conflicts with nutritional science. They want you to exclude dairy and legumes from your diet, although the supporting science is far from conclusive. Closer to the other end is Mark Sisson and Dr. Kurt Harris, who say dairy is fine if you can tolerate it, legumes should be limited only because they crowd out more nutritionally dense foods, and Paleo itself is more of a template. It informs their views, but the supporting science, or lack thereof, is more critical. Dr. Kurt Harris has formalized his approach to the problem as PaNu and his writing about it is fascinating and brilliant.

I think that too much faith in ungrounded nutritional science results in a lack of respect for the limits of human knowledge. This is part of the philosophical foundation of Paleo. It’s a mistake to believe that the current nutritional science has discovered everything necessary to proscribe the perfect diet for everyone. We are far from the final word on human health, and we would do well to ponder the probability that our scientific models are wrong. Within Paleo, evolutionary logic guides our understanding when that probability is high, but what about when that probability is low and it conflicts with evolutionary theory?

Maybe dairy, legumes, and white rice[3] really are perfectly safe foods despite not being present in Paleolithic diets? Just because a food is Neolithic doesn’t mean it must be harmful, but I think that warrants a more careful scrutiny than ancient foods.

On the other end of the continuum, we’ve been wrong about the role saturated fat played in human evolution,[5] and Richard Nikoley just dropped a bomb on the Paleo Diet’s low-carb dogma. How do we know we’re telling the right story now?

How do we know which way of thinking is correct? Or rather, is there a point on this continuum that will likely produce more truth than other points? This is the fundamental distinction that lies at the heart of the differing approaches to Paleo.

How and why one decides where they end up on the nutritional science <–> evolution/anthropology epistemic continuum is a bit of a mystery to me. Where are you on there, and how did you get there?

tAs for dairy, do you give more weight to the nutritional science that has found no smoking gun, or do you defer to evolutionary theory in the face of uncertainty and avoid dairy? There is no easy way to answer that question, but questions like it, and the way we answer them, help explain the diversity of approaches to Paleo we’ve seen in the past decade or so.

References

1. Schmitz G, Ecker J. The opposing effects of n-3 and n-6 fatty acids. Prog Lipid Res. 2008 Mar;47(2):147-55. Epub 2007 Dec 25. Review. PubMed PMID: 18198131.

2. Meisel H, FitzGerald RJ. Opioid peptides encrypted in intact milk protein sequences. Br J Nutr. 2000 Nov;84 Suppl 1:S27-31. Review. PubMed PMID: 11242443.

3. Zhang L, Hou D, Chen X, Li D, Zhu L, Zhang Y, Li J, Bian Z, Liang X, Cai X, Yin Y, Wang C, Zhang T, Zhu D, Zhang D, Xu J, Chen Q, Ba Y, Liu J, Wang Q, Chen J, Wang J, Wang M, Zhang Q, Zhang J, Zen K, Zhang CY. Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross-kingdom regulation by microRNA.Cell Res. 2011 Sep 20. doi: 10.1038/cr.2011.158. [Epub ahead of print] PubMed PMID: 21931358.

4. Lindeberg S, Ahrén B, Nilsson A, Cordain L, Nilsson-Ehle P, Vessby B. Determinants of serum triglycerides and high-density lipoprotein cholesterol in traditional Trobriand Islanders: the Kitava Study. Scand J Clin Lab Invest. 2003;63(3):175-80. PubMed PMID: 12817903.

5. Cordain L, Eaton SB, Sebastian A, Mann N, Lindeberg S, Watkins BA, O’Keefe JH, Brand-Miller J. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr. 2005 Feb;81(2):341-54. Review. PubMed PMID: 15699220.

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The Captivity of History

Most of us in the Paleo community have come to view civilization as separating us from the environment we were made for, but, in his opus, Coming home to the Pliestocene, Paul Shepard takes it a step further. He indicts history itself as a denativizing force. I’ve barely started reading the book, but it’s been fascinating so far.

A repeated question of our time is, “How do we become native to this place?” History cannot answer this question, for history itself is the great denativizing process, the great deracinator. Historical time is invested in change, novelty, and escape from the renewing stability and continuity of the great natural cycles that ground us to place and the greater community of life on earth. As Norman O. Brown writes: “Man, the disconnected animal, unconsciously seeking the life proper to his species, is man in history: repression and the repetition-compulsion generate historical time. Repression transforms the timeless instinctual compulsion to repeat into the forward-moving dialectic of neurosis which is history.”