It is good for Blood Pressure, glucose tolerance, it decreases insulin secretion, increases insulin sensitivity and improves lipid profiles.....
Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet.
Background:The contemporary American diet figures centrally in the pathogenesis of numerous chronic diseases-'diseases of civilization'. We investigated in humans whether a diet similar to that consumed by our preagricultural hunter-gatherer ancestors (that is, a paleolithic type diet) confers health benefits.
Methods:We performed an outpatient, metabolically controlled study, in nine nonobese sedentary healthy volunteers, ensuring no weight loss by daily weight. We compared the findings when the participants consumed their usual diet with those when they consumed a paleolithic type diet. The participants consumed their usual diet for 3 days, three ramp-up diets of increasing potassium and fiber for 7 days, then a paleolithic type diet comprising lean meat, fruits, vegetables and nuts, and excluding nonpaleolithic type foods, such as cereal grains, dairy or legumes, for 10 days. Outcomes included arterial blood pressure (BP); 24-h urine sodium and potassium excretion; plasma glucose and insulin areas under the curve (AUC) during a 2 h oral glucose tolerance test (OGTT); insulin sensitivity; plasma lipid concentrations; and brachial artery reactivity in response to ischemia.
Results:Compared with the baseline (usual) diet, we observed (a) significant reductions in BP associated with improved arterial distensibility (-3.1+/-2.9, P=0.01 and +0.19+/-0.23, P=0.05);(b) significant reduction in plasma insulin vs time AUC, during the OGTT (P=0.006); and (c) large significant reductions in total cholesterol, low-density lipoproteins (LDL) and triglycerides (-0.8+/-0.6 (P=0.007), -0.7+/-0.5 (P=0.003) and -0.3+/-0.3 (P=0.01) mmol/l respectively). In all these measured variables, either eight or all nine participants had identical directional responses when switched to paleolithic type diet, that is, near consistently improved status of circulatory, carbohydrate and lipid metabolism/physiology.
Conclusions:Even short-term consumption of a paleolithic type diet improves BP and glucose tolerance, decreases insulin secretion, increases insulin sensitivity and improves lipid profiles without weight loss in healthy sedentary humans.European Journal of Clinical Nutrition advance online publication, 11 February 2009; doi:10.1038/ejcn.2009.4.
UPDATE - Stephan has a good review of this study.
Translation: everyone improved. That's a very meaningful point, because even if the average improves, in many studies a certain percentage of people get worse. This study adds to the evidence that no matter what your gender or genetic background, a diet roughly consistent with our evolutionary past can bring major health benefits. Here's another way to say it: ditching certain modern foods can be immensely beneficial to health, even in people who already appear healthy. This is true regardless of whether or not one loses weight.
There's one last critical point I'll make about this study. In figure 2, the investigators graphed baseline insulin resistance vs. the change in insulin resistance during the course of the study for each participant. Participants who started with the most insulin resistance saw the largest improvements, while those with little insulin resistance to begin with changed less. There was a linear relationship between baseline IR and the change in IR, with a correlation of R=0.98, p less than 0.0001. In other words, to a highly significant degree, participants who needed the most improvement, saw the most improvement. Every participant with insulin resistance at the beginning of the study ended up with basically normal insulin sensitivity after 10 days. At the end of the study, all participants had a similar degree of insulin sensitivity.
Here's what this suggests: different people have different degrees of sensitivity to the damaging effects of the modern Western diet. This depends on genetic background, age, activity level and many other factors. When you remove damaging foods, peoples' metabolisms normalize, and most of the differences in health that were apparent under adverse conditions disappear. I believe our genetic differences apply more to how we react to adverse conditions than how we function optimally. The fundamental workings of our metabolisms are very similar, having been forged mostly in hunter-gatherer times. We're all the same species after all.
As does Dr Eades:
I was fascinated by this study because the changes were so rapid, but I was a little put off because it could have been so much better. I mean why didn’t they test a real Paleolithic diet? Probably because of nutritional correctness, i.e., fear of saturated fat.
During Paleolithic times, man primarily subsisted by hunting. The preferred food was large game animals, and Paleolithic man, a skilled hunter, wiped most of them out. And not just the large grazing animals. Paleolithic man completely decimated the Cave bear. As you can see from the photo of my Cave bear skull below (from a slide I use in presentations), these were enormous animals that didn’t go down easily. Cave bear, like all bears, had high levels of body fat, which must have been highly desired because these ferocious animals were hunted to extinction about 15,000 years ago by people wielding little more than pointed sticks. I would have to value fat a whole lot more than I do to tackle one of these guys. The largest bears that I could find the fatty acid composition for were polar bears, which should be appropriate since cave bear lived in northern latitudes. Polar bears have on average 30 percent saturated fat, 50 percent monounsaturated fat and 15 percent polyunsaturated fat. (I know these figures don’t add up to 100 percent, but they are the figures as presented in the article.)