Favourable effects of consuming a Palaeolithic-type diet on characteristics of the metabolic syndrome: a randomized controlled pilot-study

Background: The main goal of this randomized controlled single-blinded pilot study was to study whether, independent of weight loss, a Palaeolithic-type diet alters characteristics of the metabolic syndrome. Next we searched for outcome variables that might become favourably influenced by a Paleolithic-type diet and may provide new insights in the pathophysiological mechanisms underlying the metabolic syndrome. In addition, more information on feasibility and designing an innovative dietary research program on the basis of a Palaeolithic-type diet was obtained.

Methods: Thirty-four subjects, with at least two characteristics of the metabolic syndrome, were randomized to a two weeks Palaeolithic-type diet (n = 18) or an isoenergetic healthy reference diet, based on the guidelines of the Dutch Health Council (n = 14). Thirty-two subjects completed the study. Measures were taken to keep bodyweight stable. As primary outcomes oral glucose tolerance and characteristics of the metabolic syndrome (abdominal circumference, blood pressure, glucose, lipids) were measured. Secondary outcomes were intestinal permeability, inflammation and salivary cortisol. Data were collected at baseline and after the intervention.

Results: Subjects were 53.5 (SD9.7) year old men (n = 9) and women (n = 25) with mean BMI of 31.8  (SD5.7) kg/m2. The Palaeolithic-type diet resulted in lower systolic blood pressure (-9.1 mmHg; P = 0.015), diastolic blood pressure (-5.2 mmHg; P = 0.038), total cholesterol (-0.52 mmol/l; P = 0.037), triglycerides (-0.89 mmol/l; P = 0.001) and higher HDL-cholesterol (+0.15 mmol/l; P = 0.013), compared to reference. The number of characteristics of the metabolic syndrome decreased with 1.07 (P = 0.010) upon the Palaeolithic-type diet, compared to reference. Despite efforts to keep bodyweight stable, it decreased in the Palaeolithic group compared to reference (-1.32 kg; P = 0.012). However, favourable effects remained after post-hoc adjustments for this unintended weight loss. No changes were observed for intestinal permeability, inflammation and salivary cortisol.

Conclusions: We conclude that consuming a Palaeolithic-type diet for two weeks improved several cardiovascular risk factors compared to a healthy reference diet in subjects with the metabolic syndrome.

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Alex’s Notes: I suppose it was only a matter of time before another study attempting to unearth the Paleolithic diet emerged. I admit that I am drawn to these studies and become excited when they are published, if for no other reason than that they scientifically evaluate what I would call common sense. Only the most ignorant, in my opinion, would argue that modern dietary habits are suitable for our species. To go back to our evolutionary roots seems a simple solution to the mindless eating and industrial perversion of our food supply. Of course this isn’t saying we must dress up as cavemen, and indeed there is an element of modern feasibility that must be acknowledged. It would be equally as ignorant to disregard the incredible transformations that humans have made on Earth and the modern aspects of life that we take for granted. But I could go on for a while, so while the bottom line is that we must combine the best of modern medicine with that of ancient wisdom, let’s get onto the study.

Anecdotal evidence is endless when it comes to testimonials about health improvements resulting from the adoption of an ancestral-based dietary template. There have been a handful of studies that aimed to evaluate these claims, and main goal of the study at hand was to compare the metabolic effects of a Paleolithic-type diet with a healthy control diet based on the Dutch Health Council (the study was conducted in the Netherlands). Moreover, the researchers wanted to see if the outcomes were independent of weight loss.

The Paleo diet was based on standard Loren Cordain recommendations, with a focus on lean meat, fish, fruit, leafy and cruciferous vegetables, root vegetables, eggs and nuts. Dairy products, cereal grains, legumes, refined fats, extra salt and sugar were not part of it. The Dutch Health Council diet was unfortunately not elaborated upon in the study, but some digging around revealed advice similar to the United States with the exception that the focus is on dietary patterns and not individual foods or their components. The overall macronutrient breakdown of the diets appears in the table below.


Paleo Diet



  • Percentage from Animal-foods






  • Fiber (g)






  • Saturated (g)
  • MUFA (g)
  • PUFA (g)
  • Linoleic acid (g)
  • EPA + DHA (mg)













In addition to the above, the paleo dieters consumed roughly 50% more potassium, half as much calcium, 30% more iron, double the selenium, 50% more copper, 37% less iodine, double the vitamin A, 50% more thiamin (B1), 84% more niacin (B3), 64% more B6, and 173% more B12. I know, a long list of miscellaneous information, but it is interesting to note that the “healthy control” diet fell short of the paleo diet in the majority of micronutrients. But I am getting ahead of myself; we haven’t even covered the subjects yet.

Overall, 9 men and 25 women (all but 2 subjects were Caucasian) with an average age of 53.5-years were randomized to one of the two diet interventions for two weeks. Subjects were required to have at least two defining characteristics of metabolic syndrome (central obesity; hyperlipidemia; low HDL-C; hypertension; hyperglycemia), with the average amount per subject being 3. After randomization, subjects of the different diet groups could not communicate with each other and all meals were delivered at their homes free of charge by a catering service.

Before the intervention all subjects recorded their usual diet using a food record diary, which was then used to adjust the diets to meet the individual energy demands of the participants. Bodyweight was measured every second day with fluctuations of 2 kg being considered acceptable. While it is really awesome to see the researchers attempting to maintain a eucaloric study conditions, if they thought that notoriously inaccurate food logs and weight fluctuations of 5 lbs would be reliable then I can’t really do much more than shake my head and move forward.

The randomization process didn’t exactly turn out ideal either. At baseline there were significant differences between the paleo and control diets with respect to number of metabolic syndrome characteristics (3.7 vs. 2.7, respectively), low HDL-C (66% vs 12%), and hyperglycemia (77% vs 43%). Moreover, the paleo dieters were significantly heavier by 12 kg on average, and had an average BMI of 33.7 kg/m2 compared to the control’s 29.8 kg/m2. If anything this likely explains the differences in metabolic syndrome parameters. Although not statistically significant, it should also be noted that all the study participants except for 1 had abdominal obesity, the majority had hypertension, and hyperlipidemia was the least common.

Okay so two weeks later what happened?

I appreciate you bearing with me so far. I told you these studies made me excited and I don’t want to leave out any details (although I probably will, so sorry in advance). Now you are probably thinking two weeks is a really short time. I did. What changes would you expect in two weeks? Well, relative to the control group, the paleo dieters significantly lost more weight (-1.3 kg), reduced their BMI (-0.5 kg/m2), systolic blood pressure (-9.1 mmHg), diastolic blood pressure (-5.2 mmHg), triglyceride to HDL-C ratio (-0.9), total cholesterol (-19 mg/dL), triglycerides (-80 mg/dL), and increased their HDL-C (7 mg/dL). At the end of it all, the paleo group reduced their average number of metabolic syndrome characteristics from 3.7 to 2.7 while the control diet actually increased from 2.7 to 2.9. I should clarify that the above values in parentheses are the difference between the groups, not the total change from baseline.

In two short weeks that is some damn good improvement. Especially the triglycerides; wow. So what is the elephant in the room? Yep, the subjects lost weight. I’m not surprised given the tendency for people to underestimate how much they eat. If this underestimation was used to calculate the “maintenance” calories then of course there would be weight loss. And with an allowed daily weight flux of 2kg (5 lbs) the chances of preventing weight change in two weeks in slim. That said, after adding the unintentional weight loss to the analysis, the significant favorable effects for systolic blood pressure, HDL-cholesterol, triglycerides, the ratio between triglycerides and HDL-cholesterol, the ratio between total cholesterol and HDL-cholesterol, and the number of characteristics of metabolic syndrome remained, although being somewhat attenuated.

One subject in the control group reported nausea and diarrhea during the intervention which was not likely related to the intervention, and blood analysis concerning hematology and liver and kidney function showed no changes.

The bottom line…

Is that I’m impressed. The biggest limitations of this study were the small sample size and short duration, which likely underpowered the study to see significant changes of greater magnitude. Despite this, considerable improvements were evident with a Paleolithic diet in individuals with metabolic syndrome. Even the unintended weight loss could be seen as a benefit of the diet, as others have reported a paleo diet being more satiating than a reference diet in type-2 diabetics.

More research is definitely needed, and I really want to emphasize that this study must be taken in context and have its limitation acknowledged. Moreover, while meals were prepared and served to ensure the provided macronutrient ratios, no meal templates were provided so we have no idea of what either group was actually eating in terms of food. Also, what would have happened if the macronutrients were the same between groups with the only difference being the food choices? Nonetheless, the simple advice to return to our roots and eat like our ancestors continues to garner scientific support. +1 for common sense.

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