Fad diets come and go. One of the most popular fad diets of recent times is Paleo.

The Palaeolithic diet, also called the ‘Stone Age diet’, or simply ‘Paleo’, is as controversial as it is popular. It’s been increasing in popularity over the last few years, and has had some amazing claims made of it by wellness bloggers and celebrity chefs. Advocates like ‘Paleo’ Pete Evans of MKR fame, claim that the Palaeolithic diet could prevent or cure poly-cystic ovarian syndrome, autism, mental illness, dementia and obesity [1].

So what does the published medical literature say? Is there really good research evidence to support the vast and extravagant claims of Paleo?

About 10 months ago, I started reviewing the medical research to try and answer that very question. My review of the medical literature turned up some interesting results, and so rather than post it just as a blog, I thought I would submit it to a peer-reviewed medical journal for publication. After a very nervous 9-month gestation of submission, review, and resubmission, my article was published today in Australian Family Physician [2].

So, why Paleo, and what’s the evidence?

Why Paleo?

The rationale for the Palaeolithic diet stems from the Evolutionary Discordance hypothesis – that human evolution ceased 10,000 years ago, and our stone-age genetics are unequipped to cope with our modern diet and lifestyle, leading to “diseases of civilization” [3-9]. Thus, only foods that were available to hunter-gatherer groups are optimal for human health – “could I eat this if I were naked with a sharp stick on the savanna?” [10] Therefore meat, fruits and vegetables are acceptable, but grains and dairy products are not [11].

Such views have drawn criticism from anthropologists, who argue that that there is no blanket prescription of an evolutionarily appropriate diet, but rather that human eating habits are primarily learned through behavioural, social and physiological mechanisms [12]. Other commentators have noted that the claims of the Palaeolithic diet are unsupported by scientific and historical evidence [13].

So the Palaeolithic diet is probably nothing like the actual palaeolithic diet. But pragmatically speaking, is a diet sans dairy and refined carbohydrates beneficial, even if it’s not historically accurate?

Published evidence on the Palaeolithic Diet

While the proponents of the Palaeolithic diet claim that it’s evidence based, there are only a limited number of controlled clinical trials comparing the Palaeolithic diet to accepted diets such as the Diabetic diet or the Mediterranean diet.

Looking at the studies as a whole, the Palaeolithic diet was often associated with increased satiety independent of caloric or macronutrient composition. In other words, gram for gram, or calorie for calorie, the Paleo diets tended to make people fuller, and therefore tend to eat less. Of course, that may have also been because the Paleo diet was considered less palatable and more difficult to adhere to [14]. A number of studies also showed improvements in body weight, waist circumference, blood pressure and blood lipids. Some studies showed improvements in blood sugar control, and some did not.

The main draw back of clinical studies of Paleo is that the studies were short, with different designs and without enough subjects to give the studies any statistical strength. The strongest of the studies, by Mellburg et al, showed no long-term differences between the Palaeolithic diet and a control diet after two years [15].

The other thing to note is that, in the studies that measured them, there was no significant difference in inflammatory markers as a result of consuming a Palaeolithic diet. So supporters of Paleo don’t have any grounds to claim that Paleo can treat autoimmune or inflammatory diseases. No clinical study on Paleo has looked at mental illness or complex developmental disorders such as autism.

Other factors also need to be considered when thinking about Paleo. Modelling of the cost of the Palaeolithic diet suggests that it is approximately 10% more expensive than an essential diet of similar nutritional value, which may limit Paleo’s usefulness for those on a low income [16]. Calcium deficiency also remains a significant issue with the Palaeolithic diet, with the study by Osterdahl et al (2008) demonstrating a calcium intake about 50% of the recommended dietary intake [17]. Uncorrected, this could increase a patients risk of osteoporosis [18].

To Paleo or not to Paleo?

The bottom line is the Paleo diet is currently over-hyped and under-researched. There are some positive findings, but these positive findings should be tempered by the lack of power of these studies, which were limited by their small numbers, heterogeneity, and short duration.

If Paleo is to be taken seriously, larger independent trials with consistent methodology and longer duration are required to confirm the initial promise in these early studies. But for now, claims that the Palaeolithic diet could treat or prevent conditions such as autism, dementia and mental illness are not supported by clinical research.

If you’re considering going on the Palaeolithic diet, I would encourage you to talk with an accredited dietician or your GP first, and make sure that it’s right for you. Or you could just eat more vegetables and drink more water, which is probably just as healthy in the long run, but without the weight of celebrity expectations.

Comparison of the current Australian Dietary Guidelines Recommendations [19] to the Palaeolithic diet [17]

References

[1]        Duck S. Paleo diet: Health experts slam chef Pete Evans for pushing extreme views. Sunday Herald Sun. 2014 December 7.
[2]        Pitt CE. Cutting through the Paleo hype: The evidence for the Palaeolithic diet. Australian Family Physician 2016 Jan/Feb;45(1):35-38.
[3]        Konner M, Eaton SB. Paleolithic nutrition: twenty-five years later. Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition 2010 Dec;25(6):594-602.
[4]        Eaton SB, Eaton SB, 3rd, Konner MJ. Paleolithic nutrition revisited: a twelve-year retrospective on its nature and implications. European journal of clinical nutrition 1997 Apr;51(4):207-16.
[5]        Eaton SB, Konner M. Paleolithic nutrition. A consideration of its nature and current implications. The New England journal of medicine 1985 Jan 31;312(5):283-9.
[6]        Kuipers RS, Luxwolda MF, Dijck-Brouwer DA, et al. Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet. The British journal of nutrition 2010 Dec;104(11):1666-87.
[7]        Eaton SB, Konner MJ, Cordain L. Diet-dependent acid load, Paleolithic [corrected] nutrition, and evolutionary health promotion. The American journal of clinical nutrition 2010 Feb;91(2):295-7.
[8]        O’Keefe JH, Jr., Cordain L. Cardiovascular disease resulting from a diet and lifestyle at odds with our Paleolithic genome: how to become a 21st-century hunter-gatherer. Mayo Clinic proceedings 2004 Jan;79(1):101-08.
[9]        Eaton SB, Eaton SB, 3rd, Sinclair AJ, Cordain L, Mann NJ. Dietary intake of long-chain polyunsaturated fatty acids during the paleolithic. World review of nutrition and dietetics 1998;83:12-23.
[10]      Audette RV, Gilchrist T. Neanderthin : eat like a caveman to achieve a lean, strong, healthy body. 1st St. Martin’s Press ed. New York: St. Martin’s, 1999.
[11]      Lindeberg S. Paleolithic diets as a model for prevention and treatment of Western disease. American journal of human biology : the official journal of the Human Biology Council 2012 Mar-Apr;24(2):110-5.
[12]      Turner BL, Thompson AL. Beyond the Paleolithic prescription: incorporating diversity and flexibility in the study of human diet evolution. Nutrition reviews 2013 Aug;71(8):501-10.
[13]      Knight C. “Most people are simply not designed to eat pasta”: evolutionary explanations for obesity in the low-carbohydrate diet movement. Public understanding of science 2011 Sep;20(5):706-19.
[14]      Jonsson T, Granfeldt Y, Lindeberg S, Hallberg AC. Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes. Nutrition journal 2013;12:105.
[15]      Mellberg C, Sandberg S, Ryberg M, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. European journal of clinical nutrition 2014 Mar;68(3):350-7.
[16]      Metzgar M, Rideout TC, Fontes-Villalba M, Kuipers RS. The feasibility of a Paleolithic diet for low-income consumers. Nutrition research 2011 Jun;31(6):444-51.
[17]      Osterdahl M, Kocturk T, Koochek A, Wandell PE. Effects of a short-term intervention with a paleolithic diet in healthy volunteers. European journal of clinical nutrition 2008 May;62(5):682-85.
[18]      Warensjo E, Byberg L, Melhus H, et al. Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study. BMJ 2011;342:d1473.
[19]      National Health and Medical Research Council. Australian Dietary Guidelines. Canberra: National Health and Medical Research Council; 2013.