Finding the optimal diet

Clues to what our optimal diet is and what it is not.

Michael Eades takes us on a journey through the anthropological literature during an August 2018 CrossFit Health Conference, and explains what it means in terms of "off the carbs."

He explains that 99.6% of all Homo generations had no evolutionary experience with the foods we eat today....do we have clues to what diet our physiology is optimized?

Dr. Eades references a Public Health Collaboration in the UK within his presentation that compares the totality of low-carb to low-fat studies: 

"to date, there are only 62 studies, and these are the studies over the last 10 or 15 years. There are only 62 studies. If you go to the anthropological literature, there are probably a hundred times as many studies that all show the same thing, but doctors never read the anthropological literature, so they don't see that. So what they base their experience on is this relatively narrow group of studies or group of knowledge and that's been generated by RCTs. So let's take a look…."

Learn why "off the carbs" CrossFit prescription comes first

Dr. Eades continues: "...all the anthropological studies that look at the difference between hunter-gatherers and agriculturalists show a huge health disparity. When agriculture came along ...People got shorter, they got less cortical bone thickness, had more signs of inflammation, more signs of infection, more caries — dental cavities — shorter stature...

Around 27 minutes, Dr. Eades cites a 1980 study by Cassidy published in Nutritional Anthropology on two non-nomatic populations (farmers versus hunter-gatherers) roughly found in the same area, most likely from the same genetic material, both "off the couch" but separated by 4-5,000 years in time... "farmers ate a low-protein, high-carb diet ... mainly corns, beans, and pumpkins. They (also) gathered other wild plants" and they had the occasional little bit of meat. But corn was their staple...corn was the weaning food for young children... So these guys were off the couch but definitely not off the carbs. So let's see what happened to them."

What Dr. Eades finds noteworthy is the consistent contrast between farmer and hunter-gatherer remains throughout anthropological research

Present in 50% of farmer children under 5 years of age (but none of the hunters), was porotic hyperostosis and cribra orbitalia, both signs of iron deficiency anemia, which are commonly found when societies switch to an agrarian lifestyle.

Also vastly more prevalent among farmers: enamel hypoplasia, lack of proper tooth enamel development which is usually representative of severe nutritional stress.

Radiographic evidence shows Harris lines (growth arrest lines) representing mild nutritional stress more in hunter-gatherers than in farmers. Harris lines suggest hunter-gatherers had times of nutritional stress that were fairly short-lived. Whereas the farmers, if the harvest failed, were screwed.

Tooth decay was "rampant" in the farmers...an average of seven caries — seven cavities per skull. And there was tooth loss even in children (permanent teeth). The hunters had on average less than one cavity with some tooth loss in old age that was secondary to wear - they ate snails, mollusks and other things from the river with sand which abraded.

Dr. Eades cites more studies showing life expectancy was lower among farmers, infant mortality higher, and that farmer children suffered more infections than hunter-gatherer children.

Warner (2011) in the Journal of Human Evolution wrote "it is not uncommon to observe dental calculus deposits in excess of 100mg in archaeological assemblages of agricultural populations", and that in fact "cariogenic bacteria, such as S.mutans, were absent in pre-Neolithic human populations, possibly indicating low carbohydrate diets...evolutionary genomic analyses of S.mutans suggest an expansion of this species approximately 10,000 years ago, coinciding with the onset of agriculture."

"You don't have to eat sugar to get cavities, as these people have shown." - Dr. Michael Eades

Dr. Eades discusses the ancient Egyptian diet: "they were called 'artophagoi' by the Greeks: eaters of bread" and "rationed...four pounds per day".

"...if you look at the prevalence of arterial sclerosis in mummies in general — these are all mummies that have been found from agricultural societies — what you find is that under 30 years of age, about 15% of them have evidence of arterial sclerosis. You get 30-39 and it goes up there. You get to 40-49 years old, and it's over 50% of them have arteriosclerosis. And remember, this is on a diet that every nutritionist would have us eat to prevent heart disease..."

There's stable isotope analysis of the Egyptian diet, and it shows not only did they not eat much animal protein, but that all social classes basically ate the same percentages from animal sources.

Dr. Eades concludes: "… our physiology should be optimized to the diet that we have experienced during our evolutionary past. Based on all the anthropological evidence, that is not a low-fat, high-carbohydrate diet... it's pretty clear that 'off the carbs' is the way to be."

listen/watch Dr. Eades' presentation, or read the transcript (which doesn't capture all the slide information unfortunately.....)