Friday, April 1, 2011
Run through obstacles in the mud for time!!
Here is a great post by Dr. Kurt Harrin at PaNu:
In 1985, a radiologist named Boyd Eaton wrote an article for the New England Journal of Medicine called Paleolithic Nutrition. As far as I can tell, we can trace the use of the term Paleolithic Diet or Paleo diet to this article. Eaton later inspired and collaborated with Loren Cordain, a professor of exercise science at Colorado State, and author of what seems to be the most popular book with the base sequence of “paleo” in the title.
A gastroenterologist named Walter L. Voegtlin had written a book called The Stone Age Diet much earlier in 1975. Starting an unfortunate trend that continues to this day, the book had a cave man on the cover, complete with loincloth and spear. Interestingly, both Voigtlin and Eaton seemed to consider the macronutrient ratio to be the key parameter of the Paleolithic diet we should try to emulate. I consider this the least important element.
I had first heard the term paleolithic diet through Eaton’s article. When I started on this path in September 2007 I came across it and remembered that I had first read it in medical school (1985) as I had a subscription to NEJM at the time. But although when I re-encountered the article it was familiar, I can’t say it had previously made much impression, as until I read Good Calories, Bad Calories (GCBC) by Gary Taubes I still thought that food was just fuel and obesity was always due to bad genes, or overeating, or lack of exercise - the usual suspects.
Reading Taubes’ GCBC in 2007 left me with several impressions:
1) The vilification of saturated fat, and its most common source, animal foods, was a 50-year error of criminal dimensions.
My own diet, due to hubris and the belief that I had “good genes”, had thankfully never been deficient in eggs, red meat, butter or bacon. They had tried to teach us that “cholesterol” was something to fret about when I was in medical school, but even my undergraduate and medical school biochemistry at the time made that seem only vaguely plausible. Hadn’t humans been eating meat for millions of years?
It may have helped that I had a cholesterol screening in medical school. As I recall, my total cholesterol was around 140 and HDL around 50 - on a high animal fat and egg diet. And I could not with any decent disposition go more than a day without some serious meat anyway, so if it was to ultimately kill me, then so be it.
So hearing Gary Taubes on the radio, in the fall of 2007, was above all a vindication of the stubborn and instinctive nucleus of my by-then 45-year lifetime diet - animal products and their fats.
An anecdote from 1995: A former partner of mine, on seeing the breakfast I had just bought at the hospital cafeteria, remarked “Now there’s a heart-healthy breakfast!”. I looked down at my tray, which had about 3 scrambled eggs, as many sausage links and pieces of bacon, and a carton of whole milk. None of the mockery was intended for the single slice of wheat toast used to mop up the egg yolk, but the two pats of butter on the toast were surely part of the condemned. I was quite taken aback by his response as I had eaten this way since I was a child. I was to discover later that my lack of dietary consciousness had actually saved me from much of the harm that has been perpetrated by nutritional “experts” since Ancel Keys first fudged the data to make it look like saturated fat causes heart disease in the 1950s. And my partner’s wife was bit of a lefty; a Unitarian, and an artist. I suspect my partner was only “serving” me with what he would have received had he eaten such fare at home.
2) Some diseases that are very common today, which we call Diseases of Civilization or DOCs, do not occur with any frequency in native or hunter-gatherer populations until western foods are introduced.
I had never before heard evidence that some of the diseases I’d been seeing my whole career might be optional. Diseases like diabetes, heart disease, common epithelial cancers, diverticulitis, and appendicitis. Most medical schools don’t really treat this issue of DOCs. The background assumption was that cancer, heart disease and obesity are only issues because we live long enough to get them now, and aren’t we lucky for modern medicine? The diet/heart hypothesis - the idea that cholesterol or saturated fat or red meat was responsible for vascular disease and heart attacks - had been around for decades, but did not seem to be as woven into the fabric of culture as it is now. There was really no print equivalent to today’s 24/7 propaganda of pop nutrition via MSN and Yahoo, with perky titles about the latest worthless observational study associating a colorful plant with some tertiary biomarker of health status.
So we were taught that cholesterol and fat in the diet might contribute to heart attacks, but cancer, diabetes and autoimmune disorders were mostly considered just part of the human condition.
But in Gary’s book, the descriptions of populations that ate native whole-foods diets, and what happened to them when they started to eat the white man’s food, was totally eye opening and had never been hinted at in my medical school curriculum.
Gary described the common elements as carbohydrates - easily digestible carbohydrates - and this formed the basis of his carbohydrate hypothesis of diseases of civilization. Not only were dietary fats not responsible for heart attacks - and this case seems convincing to me still -but a whole suite of diseases of civilization might instead be caused by the very macronutrient that for 40 or so years has been pushed on us by governments and their confederacy of do-gooders as the antidote to the evils of artery-clogging animal fats (saturated fats) - carbohydrate. Avoid red meat. Eat more pasta and “low-fat” fare.
The nutritional transition seemed to be related to the introduction of easily digestible carbohydrate in the form of wheat flour and sugar - the staple foods of both genocidal state armies and the nanny state government rations that inevitably followed them.
Time and again it could be seen that in less than a generation, a native population that had once been free of cancer, diabetes, heart attacks, dementia, diverticulitis, appendicitis, etc., would begin to suffer from these diseases the same way that the colonizing white man had, or worse.
I read GCBC’s source works, by John Yudkin, T.L. Cleave, Weston Price, and others, and began immersing myself in the primary literature of nutrition, metabolism, endocrinology, gastroenterology, and anthropology and paleo-anthropology. I started reading many scientifically oriented blogs and thinking about what they had to say; reading papers they referenced, and following leads on pubmed, the national library of medicine’s index of peer reviewed articles.
I came to believe very strongly in the concept of the nutritional transition.
In the early days of my blog, I thought the brightest dividing line between the healthy ancestral diets and modern ones was likely to be around the time that homo sapiens had adopted the practice of sedentism - living in one spot- and therefore the time of adoption of agriculture. (It is now thought that sedentism may have preceded domestication of grains by several thousand years). This occurred around 10,000 years ago, give or take.
So “paleolithic nutrition” seemed like good shorthand for what we should be eating to avoid the diseases that came with civilization - the DOCs.
The problem came when I started to read what others before me were characterizing as key features of the “paleolithic diet”.
Some of these ideas -like avoiding eating wheat and other gluten grains - struck me as reasonable, but some were weakly supported, some were just silly, and some of them directly contradicted what I felt to be the most scientifically sound arguments in GCBC.
Hominin ancestors ate only lean meats and little saturated fat
A paleolithic diet is characterized by plenty of cultivated nuts
A paleolithic diet has plenty of sweet fruit year-round - fruits that did not even exist until they were artificially bred a few hundred years ago
A Hunter-gatherer diet always had a precise balance between “acidic” and “basic” foods and failure to maintain this precision would lead to calcium being “leached” from your bones, resulting in osteoporosis.
A paleolithic diet has plenty of grilled salmon and skinless chicken breasts.
Eating fish is essential to brain growth and general health.
Milk and cheese are causes of cancer.
Eggs can be eaten, but you should throw away the yolks to avoid too much cholesterol.
These ideas all seemed questionable to me at best, and so far have not withstood the scrutiny of either sustained pubmed searches or informed reasoning.
In the penumbra of the paleo internet and blogosphere, there seemed to be even nuttier ideas. Admittedly, most of the “paleo” movement does not embrace these, but their existence proves there is hardly a licensing system to prevent bizarre speculation about the natural human diet, without any reference to what is actually known about ancestral diets.
Hence we get:
We did not evolve to eat cooked food, and to do so is to invite disease.
We did not evolve to eat any plant food at all.
We did not evolve to eat any animal food at all.
(You all know this one - The vegan menace. Killing infants and robbing adults of their vitality is the ultimate denial of biology. Endorsed by countless brainless celebrities)
And then the inevitable combinatorial madness of:
The natural human diet is all raw plant food.
The natural human diet is nothing but ground beef and water.
The natural human diet is nothing but raw meat and water.
The natural human diet is nothing but raw fruit.
You get the picture
It seemed that the only commonly agreed-upon element among those claiming to invoke what we are “evolved” to eat, might be that cereal grains should not be a predominant part of the diet.
But then I spent some time reading at the Weston Price Foundation. WAPF is inspired by, naturally enough, Weston Price, a polymath dentist who made extensive studies of traditional foodways and modern hunter- gatherers, and attempted to identify the common elements that made them all healthy. I found that although WAPF advocated consumption of grains treated using traditional preparation methods (something I do not advocate) that on the health status of virtually every other available food I agreed more with them than with most of the paleo movement luminaries at the time - the ones claiming to be basing their recommendations on what we were “designed” to eat.
Whither Paleo Diets and Paleonutrition?
So where does that leave us? What of the concept of returning to our ancestral diet, the diet we were designed by evolution to eat?
How can we eat a Paleolithic diet if no one can agree on what it is?
The concept of a Paleolithic diet is flawed for a number of reasons. Most of the foods that we evolved eating are not actually available to us now, either in type or quantity.
And there never was any one diet eaten by the succession of species of hominins throughout our millions of years of evolution.
The idea that there has been evolution of our food sources, but little or no adaptive evolution at all by the organisms that consume them (us), is also not completely accurate.
That we are eating some things we are clearly inadequately adapted to seems certain, but the idea that the dietary bright line is narrow and exists at the 10,000 year mark is a cartoon view not supported by the science. I believe most of the dietary damage is due to industrial processing amplifying the effect of things that have always been around and were never good for us in the first place, even as I do believe wheat and other grains to the exclusion of animal products has been an issue for 10,000 years.
The idea that anything before 10,000 years ago is good for us, and anything that with a shorter history is bad for us is incoherent.
The “Paleolithic diet “ is a chimera, a myth.
No more real than a Griffin.
A beautiful thing that doesn’t really exist.
I coined the term “evolutionary metabolic milieu” or EM2, to signify that we cannot hope to duplicate the exact diet that was eaten, for all of these reasons. Instead, we can strive to use science and our reasoning to emulate the important elements of the evolutionary metabolic environment - the internal environment of our bodies.
Here was the way to connect the wonderful ideas of Taubes, Yudkin, Cleave and Price, who never really invoke evolutionary reasoning, to a sound way of thinking about diet in an evolutionary context.
A way where “Paleo” no longer refers to any particular diet eaten at any particular time, but only to paleo in the sense of “old”. Traditional Neolithic, Paleolithic and modern foods that we know are healthy or are similar nutritionally or metabolically to what archaic diets might have been like - there is room for all of these concepts.
I wrote a blog post about how my concept of evolutionary reasoning was different from trying to re-create a chimerical past.
….if foods contribute to disease, it is unlikely (but not impossible) that the bad foods are what we have been eating a long time, and much more likely that they are something relatively new
…. a food being evolutionarily novel was a likely condition for it being an agent of disease, but that novelty was neither necessary nor sufficient for agent of disease status.
It seems obvious that the universe of foods that were newer or Neolithic would provide candidates for the dietary agents of disease, and that a disease-causing agent would be very likely to be a Neolithic one
but…. being a Neolithic food alone is not sufficient to make it an agent of disease.
When we have medical and metabolic evidence that a Neolithic food is healthy and we find its constituents to be totally compatible with foods we consider Paleolithic, we can conclude that food is not in the agent of disease part of the Venn diagram.
So we are defining a healthy diet more by what is missing from it than by trying to duplicate a chimera.
If Neolithic Agents of Disease, by definition, are something that causes the nutritional transition that ushers in the DOCS, then our efforts should be focused on defining what they are.
I call such an approach, when using all available science, and not just evolutionary speculation, Paleo 2.0
Paleo 2.0 is paleonutrition where the paleo- prefix means archaic, not paleolithic
We appeal to archaic foodways to learn what is wrong with our modern Neolithic/industrial diet. These archaic foodways could be hundreds of years old, or many thousands.
We focus on the nutritional transition, then we bring all of our scientific resources to bear on finding putative Neolithic agents of disease.
In biology, “putative” means an agent that we think is the responsible or active agent, but we are always trying to falsify our hypothesis. We are always looking for evidence that we might be wrong about our agent.
In my own intellectual evolution, I have expanded and modified the carbohydrate hypothesis of the nutritional transition, as proposed by Gary Taubes, to one that does not indict a whole class of macronutrients.
I don’t believe the problem with wheat or sugar is either that they contain or are carbohydrates.
My Neolithic Agents of Disease include the following, in chronological order of introduction into our diets.
Wheat contains starch, which is fine, but along with starch wheat contains gluten, which is a complex of proteins that has been linked to a variety of diseases, and wheat germ agglutinin, that is a lectin antinutrient. Celiac disease, obesity, diabetes and mental illness are all linked to wheat consumption.
The problem in wheat is proteins, not carbohydrate. White flour is dense and highly concentrated in these problematic proteins and antinutrients. Wheat causes problems even in those who’ve been eating it for thousands of years.
Eat potatoes, sweet potatoes or root veggies for your starch, and stop eating all bread, cookies cakes and other baked goods.
Fructose is a carbohydrate, but metabolically it is quite different from the glucose that comes from starch. In small amounts or in moderate amounts in real food, fructose may not be a problem, but the ubiquity of fructose in the modern diet creates obesity, insulin resistance, fatty liver disease, and abnormal bacterial growth in the gut with consequent inflammation.
Fructose is easily minimized by simply refusing to eat processed food that comes in a box (especially “low fat” foods), and by refusing to drink caloric drinks like soda pop and fruit juices and sports drinks.
Wheat flour and fructose are the two NADs in most of the historically documented nutritional transitions.
Excess Linoleic acid
Linoleic acid is an omega 6 fatty acid, a polyunsaturated fat or PUFA. Along with n-3, the other type of PUFA, it is technically an essential fatty acid, but the actual requirement is so small it might be better considered a micronutrient. A hunter-gatherer or Paleolithic human might have had a total PUFA intake of 3% of calories. Modern north americans have a PUFA intake of around 15%, most of it due to n-6. The problem with this is twofold.
1) As n-3 and n-6 precursors compete for the same enzyme in the eicosanoid pathway, the excess of n-6 in the diet means that n-3 is outcompeted at the enzyme level. The result is a preponderance of inflammatory molecules. Increased cancer and inflammation are both likely related to this
2) Many are aware that 6:3 ratio is important, so they try to compensate by taking fish oil to balance the 6:3 ratio. This doesn’t really work too well – you can’t realistically eat that much fish, and if you take fish oil supplements, you now exacerbate the second and more important problem with excess n-6, which is your total PUFA intake. High total PUFA, especially including the highly unstable n-3, leads to oxidative damage to your cells. Your arteries, liver and other organs don't appreciate extra oxidative damage.
The way to correct the modern excess of n-6 or linoleic acid is to avoid the modern sources of it. Stop eating all temperate vegetable oils – cooking and frying oils like corn, soy, canola, flax, all of it. And go easy on the nuts and factory chicken. These are big sources of n-6, especially the nuts and nut oils.
I started reading and thinking about nutrition over 3 ½ years ago and began blogging almost 2 years ago. What I have seen in the past few years is that there are a number of other writers who also emphasize these same Neolithic Agents.
Critically, these other writers also:
1) Reject the alternative hypothesis of saturated fat or cholesterol as a Neolithic agent – the so-called diet/heart hypothesis
2) Believe that obtaining a substantial fraction of nutrition from animal sources is necessary for health
3) Discount the absolute importance of macronutrient ratios in the nutritional transition.
4) Believe that a whole foods diet that includes adequate micronutrients is the best way to eat healthy.
5) Believe that tubers, root vegetables and other sources of starch can be healthy for normal people, but that most grains are a suboptimal source of nutrition in other than small amounts.
I’ve written this post both for my regular readers at PaNu, and also for new readers who may never have heard of “paleo” diets or paleonutrition.
I invite all new readers to start with the blog posts I’ve linked to get a better idea of what PaNu is all about as a diet. It is really more of a philosophy and an approach than a set of rules to follow.
I also invite other bloggers, writers and thinkers to voluntarily affiliate with the appellation Paleo 2.0.
Many figures whom I think of as Paleo 2.0 compliant don’t and probably won't identity themselves as “paleo” at all. Given some of the nonsense I’ve seen under the rubric of paleo, I can understand that, and I’ve considered the extirpation of the label from my own blog for some time now.
But no one owns the greek word palaios. The English paleo- is just a modifier. And language evolves. We can use Paleo 2.0 until it means what we want it to. A diet that is archaic, in the sense of appealing to the past with both science and history, but not intending to re-enact a battle that has only happened in our imaginations.
If you identify with the concept of the NAD and the 5 corollary points, and want to claim the “paleo-” prefix as separate from the chimera of a paleo- “lithic” diet, then please say so.
Some will criticize my proposal as threatening to collapse a big tent.
I prefer to think of it as leaving the tent to erect a proper building.
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