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.

How To Argue with a Vegan/Vegetarian

So you’re eating meat for health and want to convince every Vegan around they are wrong? How do you do it?

You don’t. Sorry to burst your self-righteous bubble, but you simply aren’t going to change anyone’s mind by arguing with them. And even if you could, why bother? Live you life the way you want to and allow others to live their lives the way they want to. Leave the evangelizing out of it.

But, say a Vegan honestly wants to hear your perspective on meat. In that case, this story from The Atlantic (one of my favorite media outlets) should probably be your go-to link for interested Vegans. It begins…

Collectively, we have lived 52 years vegetarian or vegan. Yet we no longer think vegetarianism is the answer. Now we firmly believe foods from animals can be both healthful and ethical.

Continue reading

Why We’re Sick in One Picture

Want to see everything that is wrong with conventional diet and exercise regimens and the causes of ever-increasing chronic disease in one photo? Here it is. (Hat tip: Reddit)

It goes like this:

Eat a processed, high carbohydrate, grain-based diet that makes you fat and hungry,[1] and results in chronic disease.[2] Try to remedy the situation by doing “cardio” exercise like jogging which over-stresses your heart[3] and saturates your body with the stress hormone cortisol. Finally, double down on this failed strategy by blaming meat for your declining health and adopt an extremely high carbohydrate, unnatural[4] Vegan diet that requires endless pill-popping and results in malnutrition and heart disease.[5,6]

Thumbs up!

Why do we do this to ourselves? There are much better paths to optimal health.

References

1. Ludwig DS, Majzoub JA, Al-Zahrani A, Dallal GE, Blanco I, Roberts SB. High glycemic index foods, overeating, and obesity. Pediatrics. 1999 Mar;103(3):E26. PubMed PMID: 10049982.

2. 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.

3. Möhlenkamp S, Lehmann N, Breuckmann F, Bröcker-Preuss M, Nassenstein K, Halle M, Budde T, Mann K, Barkhausen J, Heusch G, Jöckel KH, Erbel R; Marathon Study Investigators; Heinz Nixdorf Recall Study Investigators. Running: the risk of coronary events : Prevalence and prognostic relevance of coronary atherosclerosis in marathon runners. Eur Heart J. 2008 Aug;29(15):1903-10. Epub 2008 Apr 21. PubMed PMID: 18426850.

4. Milton K. The critical role played by animal source foods in human (Homo) evolution. J Nutr. 2003 Nov;133(11 Suppl 2):3886S-3892S. Review. PubMed PMID: 14672286.

5. Shinwell ED, Gorodischer R. Totally vegetarian diets and infant nutrition. Pediatrics. 1982 Oct;70(4):582-6. PubMed PMID: 6812012.

6. Ingenbleek Y, McCully KS. Vegetarianism produces subclinical malnutrition, hyperhomocysteinemia and atherogenesis. Nutrition. 2011 Aug 26. [Epub ahead of print] PubMed PMID: 21872435.

Standard Calorie Restricted Diet May Lead to Cancer and Death

Researchers at Colorado State University recently completed a review of the limited amount of science around yo-yo dieting (scientists call it weight cycling) and cancer risk. What’s interesting is that, although consistent caloric restriction has been shown to reduce cancer risk, it appears that yo-yo dieting might increase risk of certain cancers.[1]

Weight Cycling and Cancer: Weighing the Evidence of Intermittent Caloric Restriction and Cancer Risk.

Overweight and obese individuals frequently restrict caloric intake to lose weight. The resultant weight loss, however, typically is followed by an equal or greater weight gain, a phenomenon called weight cycling. Most attention to weight cycling has focused on identifying its detrimental effects, but preclinical experiments indicating that intermittent caloric restriction or fasting can reduce cancer risk have raised interest in potential benefits of weight cycling. Although hypothesized adverse effects of weight cycling on energy metabolism remain largely unsubstantiated, there also is a lack of epidemiological evidence that intentional weight loss followed by regain of weight affects chronic-disease risk. In the limited studies of weight cycling and cancer, no independent effect on post-menopausal breast cancer but a modest enhancement of risk for renal cell carcinoma, endometrial cancer, and non-Hodgkin’s lymphoma have been reported. An effect of either intermittent caloric restriction or fasting in protecting against cancer is not supported by the majority of rodent carcinogenesis experiments. Collectively, the data argue against weight cycling and indicate that the objective of energy balance-based approaches to reduce cancer risk should be to strive to prevent adult weight gain and maintain body weight within the normal range defined by body mass index.

Previous research has shown a relationship between yo-yo dieting and morbidity and mortality, although the underlying causes are not known. It’s also shown that the prevalence of yo-yo dieting is high.[2]

Of course, adherents to the calorie counting paradigm will, as they always do, blame dieters for their diet’s failure. They will claim that this is caused by a “lack of willpower,” but now they rely on flawed, Oprah-inspired pop psychology to explain it. “You’re too stressed,” “You had a miserable childhood,” “Your life sucks, boo hoo,” etc. They won’t consider the well-established causes of their unsustainable, grain-based diet’s failure. Instead, they’ll look far and wide for vague, untestable answers in order to abstain from a much needed critical look at their own flawed nutritional theory.

In another recent study of dieters 63% of study participants engaged in yo-yo dieting.[3] If most dieters fall prey to yo-yo dieting, can’t we conclude that a standard calorie restricted diet is more likely to wreck your health, give you cancer, or kill you, then help you? When will the medical establishment stop blaming its patients and wake up to this?

There is a better way.

References

1. Thompson HJ, McTiernan A. Weight Cycling and Cancer: Weighing the Evidence of Intermittent Caloric Restriction and Cancer Risk. Cancer Prev Res (Phila). 2011 Oct 7. [Epub ahead of print] PubMed PMID: 21982873.

2. Brownell KD, Rodin J. Medical, metabolic, and psychological effects of weight cycling. Arch Intern Med. 1994 Jun 27;154(12):1325-30. Review. PubMed PMID: 8002684.

3. Osborn RL, Forys KL, Psota TL, Sbrocco T. Yo-yo dieting in African American women: weight cycling and health. Ethn Dis. 2011 Summer;21(3):274-80. PubMed PMID: 21942158.

Rice Alters Human Gene Expression

There’s been a lot of goodwill towards rice lately among the more open-minded bloggers in the Paleo community. Sure, it’s a Neolithic food, but there hasn’t been much of a case against occasionally consuming white rice for people with normal metabolic function. Removing the bran from rice (to create the white variety) removes the antinutrients too. So it may not be especially nutritious, but if you’re an athlete looking to retain or gain muscle mass, it’s a safe source of carbs.

Or so we thought.

A new study shows that very small pieces of rice RNA (microRNA) can enter the blood stream, then bind to recepters in the liver that normally work to reduce LDL cholesterol, resulting in an increase in plasma levels of LDL cholesterol.

Uh oh!

OK calm down. Before demonizing rice we’ll want to understand whether it affects small, dense LDL or large, boyant LDL, and we’ll need someone who understands biochemistry to interpret the study to get a clearer picture of it’s significance. Maybe the effect is small or counteracted by other properties of the food. Who knows? Not me, this is way above my pay grade. But it’s pretty interesting none the less that bits of rice RNA can enter the bloodstream and alter human gene expression.

The authors also suggest that microRNA may be considered as a new class of bioactive chemicals in food like vitamins, minerals, or phytosterols. Fascinating.

Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross-kingdom regulation by microRNA.

Our previous studies have demonstrated that stable microRNAs (miRNAs) in mammalian serum and plasma are actively secreted from tissues and cells and can serve as a novel class of biomarkers for diseases, and act as signaling molecules in intercellular communication. Here, we report the surprising finding that exogenous plant miRNAs are present in the sera and tissues of various animals and that these exogenous plant miRNAs are primarily acquired orally, through food intake. MIR168a is abundant in rice and is one of the most highly enriched exogenous plant miRNAs in the sera of Chinese subjects. Functional studies in vitro and in vivo demonstrated that MIR168a could bind to the human/mouse low-density lipoprotein receptor adapter protein 1 (LDLRAP1) mRNA, inhibit LDLRAP1 expression in liver, and consequently decrease LDL removal from mouse plasma. These findings demonstrate that exogenous plant miRNAs in food can regulate the expression of target genes in mammals.

References

1. 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.