Sunday, June 7, 2015

Paleolithic Diet Trials: Pastore et al


The participants were 20 people (10 male and 10 female), aged between 40-62, and with high cholesterol levels.  This trial used a non-randomised crossover design, whereby the participants started on the American Heart Association (AHA) diet first for 4 months, then switched to a Paleolithic diet for 4 months.

“The AHA guidelines emphasized a diet rich in fruits and vegetables, choosing wholegrain, high-fiber foods, foods prepared with little or no salt, and fish consumption at least twice per week, while minimizing the consumption of foods and beverages with added sugars”

“The Paleolithic diet was based on vegetables, lean animal protein, eggs, nuts, and fruit but excluded all dairy, grains, and legumes”

The AHA diet had a calorie maximum to set macronutrient targets (e.g. < 7% SFA), whereas the Paleo diet had no energy limitations.  The participants didn’t use supplements except for 800 IU/d of vitamin D3 (men and women) and 500 mg/d calcium citrate (women), and weren’t taking prescription medications

 A summary of the dietary advice


The participants reported a lower calorie intake on the AHA diet, which was mainly due to a decrease in fat.  Absolute carbohydrate intake didn’t change, but the % increased due to the lower calorie intake.  Protein intake only increased in men

The participants reported a far lower calorie intake on the Paleolithic diet, which was significantly lower than when on the AHA diet and mainly due mainly to a ~65% lower intake of carbohydrates as well as a some reduction in fat intake, but the % increased due to the much lower calorie intake.  Protein intake greatly increased on the Paleolithic diet and provided 37% of total calories.  The macronutrient ratios are strangely identical between men and women in the Paleo diet period, perhaps suggesting tighter dietary control?

Energy Intake vs Baseline

The participants lost some weight on the AHA diet, which only reached significance in the men.  The participants had further weight loss during the Paleo diet period, which was significantly different to the weight at the end of the AHA period and is consistent with the much lower calorie intake during the Paleolithic vs. AHA diet period

The AHA diet didn’t affect any of the blood lipid markers, whereas the Paleo diet significantly lowered LDL-C and triglycerides and significantly raised HDL-C.  The results of the Paleo diet are to be expected given the weight loss and if carbohydrates were mainly replaced by unsaturated fats.  Unfortunately the fatty acid composition of the diets wasn’t reported, although another reason to suspect this was that the main premise of the trial was the idea that replacing SFA with carbohydrates (mainly from grains) would worsen blood lipids and other CHD risk factors

This was a pretty simple trial where only macronutrients, weight and blood lipids were measured.  Fatty acid composition really needs to be measured in trails such as there where the outcome in blood lipids can easily just be a function of fatty acid composition.  I also think it’s a good thing to report what the participants ate, particularly for food based (rather than nutrient target based (AHA)) recommendations like Paleo. 

* There was also a study that came out earlier in the year titled: Plant-rich mixed meals based on Palaeolithic diet principles have a dramatic impact on incretin, peptide YY and satiety response, but show little effect on glucose and insulin homeostasis: an acute-effects randomised study (link).  I wouldn’t call this a ‘Paleolithic diet trial’ as it essentially compared white rice vs. isocaloric amounts of fruits and vegetables.  Guess who won

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