An excellent new study once again takes us back to the future.
Last week’s issue of The New England Journal of Medicine carried another powerful vindication of The Paleolithic Prescription, a book co-authored by Boyd Eaton, Marjorie Shostak and me just twenty years ago. Boyd and I fired the first salvo in the same journal in 1985, with an article called “Paleolithic Nutrition.”
It basically demonstrated that hunting and gathering peoples had diets very different from ours, and it looked as if clinical and experimental evidence was starting to support the idea that those diets were healthier. We followed this up with the book and with a paper called “Stone Agers in the Fast Lane,” which showed that hunter-gatherers and other “primitive” people had much lower cholesterol, much less diabetes, and much better aerobic fitness than average Americans.
The idea was that their diets, along with their activity patterns and some other aspects of their lifestyles, represented the ones we adapted to during our evolution, and since our genes did not seem to have changed drastically since then, we were just not adapted for the lifestyles most of us now lead. As we saw it, it was our ancestors, not us as their interpreters, advising the modern world.
To say that there were some scoffers is putting it mildly. Didn’t they have a low life expectancy? Yes, but almost all from infectious disease, especially in infancy, not from the chronic diseases we get from our unhealthy diets and lack of exercise.
In some ways, we were confirming what standard research had found: high levels of refined carbohydrates led to obesity and diabetes, exacerbated by lack of exercise; high saturated fat levels led to high cholesterol; low fiber intake probably helped cause colon diseases, and high salt levels probably raised blood pressure.
But on other points we seemed to be at odds with the standard advice. Most notably, hunter-gatherers had high levels of meat intake. Because their meat had little saturated fat, their overall intake of that was still low, but their protein intake was much higher than the standard advice suggested, and so was their cholesterol intake, since muscle cell membranes have plenty of that, which they use as a building block.
In the two decades since, Eaton and other colleagues, sometimes including me, have published many papers reconfirming and extending this paradigm, which could and should give coherence to health advice and motivation to millions of people confused and turned off by what seem like constantly shifting winds of official recommendations.
For most of this time, the standard recommendations were dominated by the research and advice of Dean Ornish, and of the diet popularized by Nathan Pritikin before him. Pritikin, a heart attack survivor, believed, and Ornish showed that coronary artery disease could not only be prevented but reversed by a very-low-fat, high-carbohydrate diet. Since lean meats were less available in those days and in any case not all that lean, Ornish and many others recommended very low meat intake-as Pritikin used to say, “meat as a condiment.”
This was certainly not the hunter-gatherer diet as we knew it, and in later studies it began to appear that meat and fat intake was even higher than our original estimates, so we were increasingly at odds with the prevailing wisdom. Diet guru Robert Atkins was also swimming against the tide, with his very-low-carbohydrate, high protein, high fat plan, but he was on the fringes and had conducted no research. Almost all physicians and scientists were convinced that this would increase heart disease risk.
More recently, the popular South Beach diet reinvigorated the low-carb idea, but with low fat levels. This seemed more like the hunter-gatherer model. But it is only in the last few years that actual research has started to evaluate these contesting claims.
I wrote a couple of months ago about a marvelous study last year in Sweden, showing that diabetics benefit more from an intervention based on hunter-gatherer diets than they do from the Mediterranean diet that has been shown to help in heart disease. Now the new study, also very rigorous but more wide-ranging and much longer, once again confirms that hunter-gatherer diets are healthy options for the modern age.
It was an international collaboration centered in Israel. It randomly assigned 322 moderately obese, middle-aged, mostly male subjects to one of three diets: a low-fat diet based on American Heart Association guidelines; a Mediterranean diet rich in vegetables, low in red meat, but with substantial poultry and fish; and a low-carb, otherwise unrestricted diet. Only on the last could subjects eat all they wanted.
People lost weight on all three for six months (most on the low-carb), then rebounded part way and maintained some weight loss for two years-at the end of which the ones on the low-fat diet weighed more than the other two groups. HDL (good) cholesterol, triglycerides, and other lipid measures were also worse on the low-fat diet than on the other two, a paradoxical result also found in other studies.
Fasting glucose, fasting insulin, and insulin resistance also showed group differences, with the non-diabetics best off on the low-carb eat-all-you-want diet and the people who already had the disease best off on the Mediterranean. A number of these measures improved on the low-fat diet too, but significantly more so on one or both of the other two.
Anthropologists argue back and forth about it, but the hunter-gatherer diet lies somewhere on a continuum between the low-carb diet and the Mediterranean (the red meat they eat comes from wild animals with lipid profiles like those of poultry and fish). So this important study represents another vindication of the model we put forward twenty and more years ago. And meanwhile, some aspects of the standard advice have moved pretty steadily in the hunter-gatherer direction. Not surprising, really, when you consider that it was our diet for hundreds of thousands or even millions of years.