As y'all probably know by now, part of my daily web reading is to check in on what's happening on paleobuzz.com followed blogs ... which landed me at Dr. BG's Animal Pharm in a post discussing a 2009 study by Linda Frassetto, et.al. (Frassetto presented at AHS12): Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet.
This post is not addressing Dr. BG's post and the results of this study ... perhaps another time for that one ... but rather the diet used in the study. From the abstract, bullet-pointed and formatted for clarity:
Methods: We performed an outpatient, metabolically controlled study, in nine non-obese 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:
- Significant reductions in BP associated with improved arterial distensibility (- 3.1±2.9 , P=0.01 and +0.19±0.23, P=0.05)
- Significant reduction in plasma insulin vs time AUC, during the OGTT (P=0.006)
- 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.
OK ... now when you hear paleo diet, what comes to mind? Bacon and eggs for breakfast? Fatty meats and organs cooked in coconut oil or ghee? Heavy cream in your coffee and dark chocolate covered macadamias for a snack? Low carb, high fat perhaps? Higher on the saturated fat, easy on the PUFA? Well ...
In 1985, anthropologists Eaton and Konner (1985) introduced the general medical community in ‘paleolithic nutrition. A consideration of its nature and current implications’. ‘Paleolithic’ refers to the period of history of the genus Homo, beginning more than 2 million years ago and continuing until about 10 000 years ago (10 kya, when the neolithic period began) when humans began to cultivate plants (predominantly cereal grains) and domesticate animals (Brandt, 2007). During that interval (more than 2-million year), culminating in the emergence of today’s sole Homo species, Homo sapiens, about 200 kya (McDougall et al., 2005), our ancestors, including Homo sapiens, lived as hunter-gatherers, eating wild animal-source foods (lean meats, internal organs, bone marrow, but no dairy) and uncultivated plant-source foods (mostly fruits, nongrain, vegetables, nuts, but no legumes). As the 10 000 or so years since the beginning of the agriculture and animal domestication began,that is less than 1% of Homo evolutionary time—leaves little time for evolutionary forces to redesign the core metabolic and physiological processes in a major way in response to the major dietary changes introduced by the agricultural revolution and food animal domestication, the genetic makeup of contemporary humans may more closely optimize core metabolism and physiology when they consume a diet more closely resembling our ancestral hunter-gatherer’s preagricultural diet (Eaton et al., 1988; Cohen, 1989; Jansson, 1990; Eaton and Cordain, 1997; Neel, 1999; Simopoulos, 1999; Eaton and Eaton, 2000; Sebastian et al., 2002, 2006; Lindeberg et al., 2003b, 2007; Mann, 2004; O’Keefe and Cordain, 2004; Cordain et al., 2005).
Now, I was taken to task a bit here in comments recently for suggesting pretty much what is written above in the introduction of this paper: In short, that the paleo diet is predicated on the notion that the genome has not changed in the 10K or so years of neolithic agriculture and that a diet comprised only of foods that might have been available back then would be more appropriate for our human physiology.
While it's perfectly acceptable to "tweak" off of a paleo diet, acknowledging, for example, adaptations to dairy and such, this creates a problem with the few clinical trials like this one that have been done on paleo diets. (Trials on carbohydrate restriction suffer similar issues in terms of what constitutes a low carb diet). So what diet produced these wonderful metabolic changes?
They ramped them up (there appears to be concern over increasing potassium too abruptly) to where the final paleo diet consumed for 10 days was:
Usual diet: 18% of calories from protein, 44% from carbohydrates and 38% from fats
Paleo diet: 30% of calories from protein, 38% from carbohydrates and 32% from fats
They were eating almost 15% more calories, but there was no significant change in carbs or total fat intake here, thus almost all of the increased caloric intake came from protein. Also sat fat intake was cut in half while PUFA intake tripled and MUFA intake increased 40%. It's too bad they didn't give portion sizes for the foods, but it would appear there was a significant increase in fructose consumption (they consumed quite a bit of OJ during the ramp up week as well).
OK ... so increase protein (insulinogenic and IGF stimulating) , drop the fat and carbs equally by percent but not by absolute amounts, and see metabolic improvements in glucose metabolism in short order.
Is this your paleo diet? Is it "by default" low carb? I would notice that the *usual* diet was not the 500g carb/day we're accustomed to hearing for the SAD, but rather half that at around 250g. Dr. BG lists a number of 2009 blog entries about this study. Since he's the biggest wig amongst them, I'll simply highlight Mark Sisson's contribution, which consisted mostly of "I'm not going to say I told you so" but hailing the results of this study as some sort of endorsement of his Primal Blueprint. This highlights the one thing that gets rather usual in these studies -- When you look beyond the headlines, the tested diets bear little to no resemblance to the diets those heralding the studies are promoting. These subjects ingested roughly 100g of insidiously weight gaining carbs in addition to the 150g regular insulin surge inducing carbs. They lowered their "healthy primal" saturated fat intake while increasing their MUFA and PUFA (if ratio improved, absolute increase in O6's would be inevitable). They ate pork tenderloin (lean), tuna (lean) and chicken and turkey breast (lean, lean).
One last comment -- what with this current 2012 trend of being a "fat burning beast" or (gag) in "nutritional ketosis" eating fewer and fewer carbs and more and more fat. I think this study serves as a great reminder of the folly of TWICHOO and its cousins including any variation of carbs causing insulin resistance and metabolic syndrome and all manner of metabolic derangement, mitochondrial mahem and wreaking havoc and irreparable damage upon one's metabolism.