Primitive Nutrition Critique Parts 4 and 5

In The Protein Debate, Loren Cordain wrote the following:

He seems to be saying two things:

1)  Nutrition as a science suffers from “chaos, disagreement, and confusion.”

And

2) Use of ‘an evolutionary model’ would elimate “chaos, disagreement, and confusion”  by providing “coherent way to interpret the data.”

With regard to the first statement, I don’t know where he finds the “chaos, disagreement, and confusion” in nutrition science.  I can’t find this in any standard nutrition textbooks, in the National Academy of Sciences Food and Nutrition Board Dietary Reference Intakes publications, or among various expert panels making dietary recommendations to the public.  Among these scientific sources, I find very little or no debate as to human requirements for protein, fat, carbohydrate, vitamins, and minerals.   Also, the general guidelines for diet vary little from expert panel to expert panel.  Do I see a straw man here?

Or is Cordain preoccupied with the confusion among lay people, generated by the profusion of fad diet books?

Or is the disagreement he refers to the disagreement between his recommendation for a low-carbohydrate, high-protein diet, and the science which shows that humans only require a small amount of protein (one-third of what Cordain advocates) and lots of carbohydrates?

With regard to the second statement above, this implies that we should find even greater agreement among those who profess to use “an evolutionary model” to evaluate nutrition than we do among the conventional sources that Cordain derides. 

So let’s take a look.

Fruits and Vegetables

Regarding consumption of fruits and vegetables, expert panels of the USDA,  American Heart Association, National Cancer Institute, American Institute for Cancer Research, World Cancer Research Fund, and many others generally agree that we benefit from eating fruits and vegetables.

In contrast, among those using an evolutionary model, Cordain believes that we should eat them because they provide important phytochemicals that protect against cancer and inflammation, but evolutionary model advocate and radiologist Kurt Harris, M.D. has once expressed the view that “plants and plant compounds are not essential or magic,” stating:

"Show me a randomized intervention that shows the benefits of fruits and vegetables. Such trials have been done and they have not shown a benefit." 

Unfortunately I do not know to which trials he refers as he provided no reference.  In that essay, Harris added that the idea that a particular plant compound is essential is inherently implausible and in need of a rigor of proof suitable for establishing the idea that there exists some extraterrestrial intelligence:

"To overcome the inherent implausibility of a particular compound or plant being essential or uniquely beneficial to health, there must be a high standard of proof.

"Similar to the level of proof there that there is extraterrestrial intelligence. It's implausible, so good evidence is needed."

Dr. Harris has amended his view on this topic somewhat since those words, and has written a blog indicating he believes that some plant compounds may provide benefits and "that eating some veggies is a hedge against going without unspecified beneficial compounds."

My question is, if the evolutionary model is so helpful for eliminating chaos and confusion, why didn't it clearly favor one or the other of these views about plants and plant compounds? 

Nutrition science recognizes many plant compounds essential to health (although apparently not those that Dr. Harris had in mind in his 'plant compounds are not essential' essay).  Those include, minimally, the vitamins thiamin, riboflavin, niacin, pyridoxine, pantothenic acid, folate, ascorbic acid, phylloqunione (vitamin K1), tocopherols (vitamin E); the essential fats linoleic and linolenic acids; and the essential amino acids isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine.

All of these compounds are originally synthesized by plants and, except for niacin, appear in animal tissues only because the animal ate plants directly or ate another animal that ate plants.  The evidence that we require these plant compounds is thoroughly discussed in the various Dietery Reference Intakes publications of the Food and Nutrition Board of the National Academy of Sciences as well as numerous standard nutrition textbooks.

Amazingly, nutritional scientists discovered the essentiality of these nutrients for modern humans without speculating about the habits of stone age hunter-gatherers, consulting archaeologists, or asking anthropologists what isolated hunter-gatherers eat. Am I to believe that all of this talk of essential nutrients is nonsense because it was discovered without applying an evolutionary model?

In addition, while I would agree that it is implausible that any particular plant (e.g. spinach) is essential to health, plants world-wide have similar constituents (including non-vitamin phytonutrients).  For example, polyphenols occur in many species of plants world-wide.  To my knowledge, no nutrition scientist is arguing that any particular plant is essential or uniquely beneficial to human health, but many would suggest that humans have adapted to (possibly to become reliant upon) consumption of families of plant compounds (e.g. polyphenols).  I find this considerably more plausible than the idea of extraterrestrial intelligence (I don't know if Dr. Harris has changed his opinion here), since we already have established a human need for the plant compounds I have listed above.

So far as I can tell, except for vitamin D, which our own bodies synthesize if exposed to sunlight, not one nutrient mentioned in those FNB documents as an essential dietary component for humans is originally synthesized only by animals; i.e. all are originally synthesized by plants or microbes, or present as inorganic components of the earth's crust.  This table lists the essential nutrients and their original sources:

Nutrient	Original Source(s)
Essential amino acids (9)	Plants
Linoleic acid	Plants
Linolenic acid	Plants
Glucose	Plants
ß-carotene (provitamin A)	Plants
Tocopherols (vitamin E)	Plants
Cholecalciferol (vitamin D3)	Endogenous synthesis after sunlight exposure
Phylloquinone (vitamin K)	Plants
Thiamine (B1)	Plants and microbes
Riboflavin (B2)	Plants and microbes
Niacin (B3)	Plants
Pantothenic acid (B5)	Plants and microbes
Pyridoxine (B6)	Plants and microbes
Folate	Plants and microbes
Cobalamin (B12)	Microbes
Ascorbic acid (vitamin C)	Plants
Minerals	Rocks, soil (brought into the food chain by plants)

Cholesterol

Regarding dietary and blood cholesterol, scientific bodies consistently agree that dietary cholesterol is not beneficial or essential, and reducing cholesterol levels is desirable and necessary for avoiding cardiovascular disease (atherosclerosis).  For example, the NAS Food and Nutrition Board writes:

"There is much evidence to indicate a positive linear trend between cholesterol intake and low density lipoprotein cholesterol concentration, and therefore increased risk of coronary heart disease (CHD). A Tolerable Upper Intake Level is not set for cholesterol because any incremental increase in cholesterol intake increases CHD risk. Because cholesterol is unavoidable in ordinary diets, eliminating cholesterol in the diet would require significant changes in patterns of dietary intake. Such significant adjustments may introduce undesirable effects (e.g., inadequate intakes of protein and certain micronutrients) and unknown and unquantifiable health risks. Nonetheless, it is possible to have a diet low in cholesterol while consuming a nutritionally adequate diet. Dietary guidance for minimizing cholesterol intake is provided in Chapter 11."

Let me emphasize some lines from this passage:

"There is much evidence to indicate a positive linear trend between cholesterol intake and low density lipoprotein cholesterol concentration, and therefore increased risk of coronary heart disease (CHD)."

"....any incremental increase in cholesterol intake increases CHD risk."

Of interest, this paragraph illustrates my previous point that the dominant nutrition paradigm includes Cordain's belief that elimination of animal foods from the diet "may introduce undesirable effects (e.g., inadequate intakes of protein and certain micronutrients) and unknown and unquantifiable health risks."  This passage documents that Cordain's perspective is conservative, not revolutionary, compared to Campbell's, because, unlike Cordain and the Food and Nutrition Board, Campbell does not believe that eliminating cholesterol from the diet would result in protein or micronutrient deficiencies or 'unknown and unquantifiable health risks.'  

Nevertheless, the  Food and Nutrition Board maintains that dietary cholesterol (i.e. animal food) intake increases coronary heart disease risk.  The National Heart, Lung, and Blood Institute concurs and adds that "the higher your blood cholesterol level, the greater your risk for developing heart disease or having a heart attack."    Their publication "High Blood Cholesterol: What You Need To Know" includes this:

Again, no confusion or chaos apparent in the nutrition science Cordain has attacked.

In contrast, among those using the supposedly ‘unifying’ evolutionary model, Cordain believes that LDL cholesterol should be less than 70 mg/dL, but Kurt Harris, M.D. has expressed an opposing opinion of no confidence at all in any version of the lipid hypothesis:

"I do not believe in any of the versions of the lipid hypothesis, ranging from Ancel Keys' original idea that cholesterol or dietary fat clogs the arteries, to the currently fashionable one that “small, dense” LDL particles are like microscopic rodents that are designed to burrow under the intima of your blood vessels and kill you."

Why didn't their common use of an evolutionary model eliminate this disagreement?

Saturated Fat

Regarding saturated fat, scientific consensus documents such as the Food and Nutrition Board (FNB) of the NAS clearly state that we have no requirement for dietary saturated fat and any incremental increase in dietary saturated fat increases heart disease risk.  Here again I quote the FNB Dietary Reference Intakes for Fats:

"Saturated fatty acids are synthesized by the body to provide an adequate level needed for their physiological and structural functions; they have no known role in preventing chronic diseases. Therefore, neither an AI nor RDA is set for saturated fatty acids. There is a positive linear trend between total saturated fatty acid intake and total and low density lipoprotein (LDL) cholesterol concentration and increased risk of coronary heart disease (CHD). A UL is not set for saturated fatty acids because any incremental increase in saturated fatty acid intake increases CHD risk." [emphasis added]

You will find that all major expert panels around the world maintain this position. 

In contrast, among those claim to use the supposedly ‘unifying’ evolutionary model, Cordain believes the evolutionary model prescribes lean meat and low intake of dietary saturated fat, while Michael Eades, M.D. thinks that the evolutionary model prescribes fatty meat and high intake of saturated fat.

Should I really believe that the members of the Institute of Medicine's Food and Nutrition Board, composed of individuals who have invested their whole lives in studying nutrition both as scholars and bench scientists, do not understand the effect of nutrition on CHD risk, because they failed to use an evolutionary model?  Do you think the members of the FNB know the difference between correlation and causation?  Or did they get to the top of their field without mastering this concept presented in any undergraduate course in statistics or science?

Fitness 

Regarding fitness, at least one advocates of looking at things with an evolutionary model, Art DeVany believes that the scientific data proscribes distance running (note:  in the comments below Dr. Harris disavows using an exclusively evolutionary model to come to this conclusion), while Daniel E. Lieberman, a Harvard evolutionary biologist, and Dennis M. Bramble, a biologist at the University of Utah,  believe that an evolutionary model prescribes distance running.  If the evolutionary model is so powerful for eliminating chaos and confusion, why don't advocates of an evolutionary model agree on this point?

Confusion Within the Evolutionary Model

The ‘evolutionary model’ offered by Cordain and low-carbers also seems to introduce some confusion into the ‘evolutionary model’ itself.

According to this model, we should eat the imagined meaty low-carbohydrate diet of stone age mammoth hunters in order to increase our metabolic rates and lose body fat.    

Does this make evolutionary sense? 

I mean, would a high metabolic rate induced by a high protein/lean meat intake really benefit to a stone age hunter gatherer who already had difficulty getting hold of enough food to meet his metabolic needs?  

And would a low body fat level  achieved by a meaty low carb diet be an evolutionary advantage to humans dealing with extremely cold winters during the ice ages? 

Groking the Source of Confusion

Could it be that Paleo advocates are confused and confusing because they rely on an imaginary Grok for their guidance rather than science?   

By that I mean that the paleo diet ‘evolutionary’ model is based on largely imagining what stone age people did.  In case you didn’t notice, we don’t have any body composition data, diet or medical records, photos, or videos from the stone age people the paleo crowd wants to emulate.  

 This means you have to use your imagination to come up with any picture of them and their diets and lifestyles.   My imagination is different from yours, so we just might come up with different Groks to emulate. 

Cordain and his colleagues used their imaginations when they published "Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet"  in the British Journal of Nutrition.  

I have realized that few if any of the conclusions in this document are subject to either confirmation or falsification.  You can invent any number of 'models' of paleolithic diets and none can be either confirmed or falsified simply because we have no direct access to or records of East African Paleolithic human diets.

Let me put it this way.  If I estimate that present-day Italian farmers consume 400 g of wheat bread and 3000 kcal per day in the winter, I can test my estimate by going to Italy, collecting diet records, and doing the math.  Others can test my estimate by the same procedure.  I could be proven wrong by someone else.  But if I estimate that Neanderthal females consumed 1200 kcal, 500 mg of DHA, and 30 mg of vitamin C daily in the summer, neither I nor anyone else can test my estimate against reality because neither Neanderthals nor their habitat exist any longer. 

And that is my introduction to these two videos: