How Safe Is Your Primal Diet?

We now see that there is significant variation between individual responses to differing diets.

I have a love-hate relationship with the paleo diet. On the one hand, I think it’s a cool concept to help people to have a better mental framework for a diet that is based on good, whole, unprocessed foods. On the other hand I think that people can become far too overzealous about what is and isn’t ‘paleo’. Plus, I started doing this whole, lower-carb, nutrient-dense nutrition gig way before paleo was a big thing (down my neck of the woods, anyway). That’s why I tell my students that I’m more of a spaceman than a caveman…

The premise of the paleo diet and many other emerging (possibly re-emerging) diet styles, from ‘primal’ through the various iterations of ‘real-food’ eating that are now commonplace, is that genetically we haven’t changed much since the time of the earliest humans. Research has shown that: “From a genetic standpoint, humans living today are Stone Age hunter-gatherers displaced through time to a world that differs from that for which our genetic constitution was selected”.1 Of course, more moderate forms of these diets take into account that we have experienced some pretty big changes as a result of the agrarian shift towards cultivated grains and domesticated animals (like the ability of most people of European extraction to digest lactose). Overall, these diets can be grouped together under a general heading of ‘ancestral-type’ diets.

The ‘modern’ paleo diet seeks to emulate traditional hunter-gatherer diets by eliminating foods that are that were not present (in large amounts) in the diets of most hunter-gatherers. There are many variations on the paleo theme and most people now follow some iteration of paleo that could differ from the original template. For example, many now would classify their diet as ‘primal’—a style of nutrition that is quite diverse and typically like paleo, but with the addition of some dairy, occasional sprouted legumes, and even occasional grains. The following describes common paleo guidelnes.

What to eat:

  • Free range, organic meat, eggs and fish
  • Nuts and seeds
  • Fibrous vegetables
  • Root vegetables: sweet potatoes, yams, etc.
  • Berries and fruit
  • Virgin nut and fruit oils: olive, macadamia, coconut

What to avoid:

  • Factory farmed meats, battery eggs
  • Grains and legumes
  • Seed oils
  • Dairy

Did Paleolithic Man Really Eat Like That?

Critics of the paleo diet point to the lack of consistency in hunter-gatherer diets. In other words, there is no solitary hunter-gatherer diet. For example, analysis of 229 hunter-gatherer diets from around the world found a high variance in carbohydrate intake (approximately 3%-50% of daily calories). However, the authors noted that carbohydrate intake in almost all hunter-gatherer populations is lower than that currently recommended for health,2 and it’s fair to say that all hunter gatherer populations have an absence of refined and processed foods. It’s also interesting to note that many critics of real-food based diets like paleo are advocates for the Mediterranean diet, and yet there is no ‘one’ Mediterranean diet either. It is more important to look at either diet (because they are both great) not as rigid prescriptions of certain foods for all people, but instead a compendium of available foods from which to choose.

How do you determine what works for you?

Hunter-Gatherers Were ‘Healthier’

Hunter-gatherer populations such as the Inuit, Australian Aboriginals, Hadza, and others that have been studied were indeed, until the introduction of modern diet and lifestyle, robustly healthy and with a significant absence of the metabolic disorders of obesity and diabetes that plague the modern, western world.3, 4, 5, 6 They couldn’t be said to have had it easy though, with higher mortality rates from communicable diseases, war, homicide, and medical complications, especially during childbirth. But the most pertinent point to note is that the diseases that are the biggest affecters of quality and length of life in the modern world (the non-communicable diseases of lifestyle) appeared with lower prevalence for these people. Overall, it is now accepted that at the time of the invention and rapid uptake of agriculture around 10,000 years ago, people’s height decreased and health suffered.7

Paleo or Ancestral-Type Diets Are Safe

There has been a remarkable amount of negative attention paid to the ‘real-food’ food movement. This seems at odds with a pragmatic overview of nutrition, in which any diet that prioritises more nutrient-dense, whole, unprocessed foods should be considered a good one. The evidence does suggest that overwhelmingly ancestral-type diets are safe, and they may provide considerable benefits for weight-management, cardio-metabolic health, and for satiety and hunger-reduction. The relatively few trials that have been performed on the paleo diet thus far show compelling benefits for satiety (when compared to ‘best-practice’ dietary guidelines,8 best-practice diabetic meal plan,9 and the Mediterranean Diet10), cardiometabolic risk indicators,11, 12 and fat-loss,13, 14 with no adverse effects reported.

Much of the criticism of paleo diets springs from the assumption that it is low in carbohydrates and that this might negatively affect thyroid status (which in itself is contentious) or cause other hormone irregularities However, the paleo diet isn’t by nature low in carbohydrates as it can (depending on how it’s applied) include appreciable carbohydrate from sweet potato, yams, vegetables, berries, and some fruit, which would be more than adequate for most people who benefit from moderate or even higher carbohydrate loads.

So, there’s no good reasons to believe that a paleo or other ancestral-type diet would negatively affect health. However, a severely carb-restricted paleo diet could possibly affect hormone levels for some. Carbohydrate restriction can increase cortisol levels (one of our major stress hormones), although this hasn’t been noted in the existing work on the paleo diet, and reduce levels of the sex hormones (especially testosterone). This cortisol to free testosterone ratio is a key marker of fatigue syndromes. It is important to note that some of these distortions may occur in the transition phase to a lower carbohydrate diet and may not last if one becomes sufficiently ‘fat adapted’ and are also likely to be related to the genetic and ethnic predisposition of an individual to either a low or higher-carb diet.

Do What Works for You

If paleo is working for you, there’s no compelling safety reason to stop. If you practice a different form of ancestral or primal diet and that is working, same goes, stick with the programme soldier and keep on getting those results. At the end of the day, we are seeing that there is significant variation between individual responses to differing diets. One of the absolute keys to success is figuring out what works for you, and what is the easiest to stick to. If you can’t stick to diet consistently for a long period, its use is going to be incredibly limited.

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1. Eaton SB, Konner M, Shostak M. Stone agers in the fast lane: Chronic degenerative diseases in evolutionary perspective. The American Journal of Medicine. 1988;84(4):739-49.

2. Ströhle A, Hahn A. Diets of modern hunter-gatherers vary substantially in their carbohydrate content depending on ecoenvironments: results from an ethnographic analysis. Nutrition Research.31(6):429-35.

3. Sinclair HM. The Diet of Canadian Indians and Eskimos. Proceedings of the Nutrition Society. 1953;12(01):69-82.

4. O’Dea K. Westernisation, insulin resistance and diabetes in Australian aborigines. Med J Aust. 1991;155(4):258-64.

5. O’Keefe JJH, Cordain L, Harris WH, Moe RM, Vogel R. Optimal low-density lipoprotein is 50 to 70 mg/dlLower is better and physiologically normal. Journal of the American College of Cardiology. 2004;43(11):2142-6.

6. O’Dea K. Westernization and non-insulin-dependent diabetes in Australian Aborigines. Ethn Dis. 1991;1(2):171-87.

7. Mummert A, Esche E, Robinson J, Armelagos GJ. Stature and robusticity during the agricultural transition: evidence from the bioarchaeological record. Economics and human biology. 2011;9(3):284-301.

8. Bligh HF, Godsland IF, Frost G, Hunter KJ, Murray P, MacAulay K, et al. 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. The British journal of nutrition. 2015;113:574-84.

9. Jönsson T, Granfeldt Y, Lindeberg S, Hallberg A-C. 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.

10. Jönsson T, Granfeldt Y, Erlanson-Albertsson C, Ahren B, Lindeberg S. A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease. Nutr Metab (Lond). 2010;7:85.

11. Masharani U, Sherchan P, Schloetter M, Stratford S, Xiao A, Sebastian A, et al. Metabolic and physiologic effects from consuming a hunter-gatherer (Paleolithic)-type diet in type 2 diabetes. Eur J Clin Nutr. 2015.

12. Frassetto LA, Schloetter M, Mietus-Synder M, Morris RC, Jr., Sebastian A. Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet. Eur J Clin Nutr. 2009;63(8):947-55.

13. Mellberg C, Sandberg S, Ryberg M, Eriksson M, Brage S, Larsson C, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. Eur J Clin Nutr. 2014;68(3):350-7.

14. Ryberg M, Sandberg S, Mellberg C, Stegle O, Lindahl B, Larsson C, et al. A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women. Journal of Internal Medicine. 2013;274(1):67-76.

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