A meta-analysis of the Paleolithic nutrition pattern; an interview of authors
Just today, the American Journal of Clinical Nutrition – the most prestigious nutrition journal in the world – published a systematic review and meta-analysis of the paleolithic nutrition pattern (the Paleo diet).
The audio interview below is with study authors, Hanno Pijl, M.D., Ph.D., and Esther van Zuuren, M.D., both of Leiden Unversity in the Netherlands. They, along with authors Eric Manheimer and Zbys Fedorowicz, first performed a systematic review of six online publication libraries for all possible qualifying research. From there, they winnowed the list to four studies, pooling together 159 subjects for their analysis, looking for mean differences in primary endpoints related to metabolic syndrome: 1) waist circumference, 2) blood pressure, 3) triglycerides, 4) HDL cholesterol, and 5) blood sugar concentration. Secondary endpoints included change in body weight, even though some of the studies included in the analysis tried to prevent weight change so that the results would be less confounded by it. Weight loss, while healthy for someone who are overweight, can also improve these endpoints independently, making it harder to know if it is the nutritional properties of the diet or the weight loss that influenced results. We discuss this specifically in the interview, which you can listen to here in its entirety:
Why Try This Dietary Pattern?
The quick rationale for this nutritional pattern is as follows: Hunter gather societies – either anthropological estimates of ancestors and assessments of modern-day native groups – seem significantly less burdened, if not almost completely free from, degenerative diseases that plague modernized societies. Additionally, when members of natural living societies adopt modern diets and lifestyles, their health worsens. When some now-modernized people return to their former natural living lifestyles, they show marked improvements in their overall health. See research by Kerin O’Dea for examples. These observations segued into several uncontrolled trials, first evaluating the paleolithic nutrition pattern over short timeframes, and the results were positive at improving metabolic health markers in healthy people.
Is Paleo Really Paleo?
Before I continue with this article, I must comment that a modern-day Paleolithic-based nutrition pattern is veritably nothing like an actual Paleolithic diet. Virtually all the plants we eat today are products of agriculture (and we’re eating vastly less plant diversity than our ancestors, too), and for the most part, for most people, the meats (mostly muscle, and few organs) we eat today are from domesticated animals. Together, the nutritional impact of meat and vegetables today is distinct from the set of nutrients delivered by meats and plants of our ancestors, not even to mention the extensive list of cooking techniques we use to process foods.
In other words, the foods entering out body today are very different that what entered the body 10,000 years ago, or earlier. And this is totally fine. A modern-day Paleo diet is meant to help us eat the foods that are more similar to our ancestral past, and by doing so, help us avoid the nutritional pitfalls that literally dominate our modern food environment. The Paleo diet isn’t meant to be a perfect replica of a diet in that time period, it’s a concept that is meant to guide us to better food choices given the food options we have access to now.
The Paleo Diet Is in Its Awkward Teenage Years
The appeal of the concept of Paleo is strong for many. The state of modern health and wellness is nothing less than scary: long-term health outcomes based on nutrition are extraordinarily hard to study, some recommendations on what we eat can appear downright wacky, and authoritative guidance can shift. In 2014, Paleo was the most searched health term globally, yet organizations like the US News and World Report listed Paleo as dead last in their recommendations of sound diets, citing lack of substantive evidence. For many people who have experienced real health benefits making the change to Paleo, or simply people who have bought into the argument, this condemnation leads only to further distrust of nutritional authorities. Yet, while I would be embarrassed to be a part of a group of nutritional figures that rated the Paleo diet last amongst their recommendations, they are not incorrect to claim that more evidence is needed. It is, and that’s why I’m pleased to share this audio interview of the authors of the rigorous meta-analysis with you.
Results, Interpretations, and Discussion from the Analysis
Paleolithic nutrition resulted in greater short-term pooled improvements on each of the 5 components of the metabolic syndrome than did currently recommended guideline-based control diets, however, this change did not reach significance for two of the five components (HDL and fasting blood sugar).Paleo outperformed guideline-based control diets on each 5 components of metabolic syndrome Click To Tweet
This is very impressive. To rephrase, this says that the Paleolithic nutrition pattern outperformed (some) diets currently recommended to treat this condition. Some very important questions, however, came up during the interview, including a discussion on what characteristics of the diet pattern might be generating the positive results. Essentially, any component of the diet that limits inflammation is likely crucial.
Interestingly, Paleo is most popularly thought of as the exclusion of grains, legumes, and dairy. It is important to acknowledge, however, this is disputed by researchers, such as Karen Hardy of the Universitat Autònoma de Barcelona, who argue that starch, as in the form of tubers, was also a staple food for our ancestors starting 800,000 years back, once humans began to use fire for cooking. Hanno and I discuss the nuance of carbohydrate consumption in today’s world, talking about how it can be safe for many, and how it’s the form consumed that is the key distinction. Hanno went as far as to say that processed carbohydrates are not healthy for anyone, even those free of any metabolic disease. I interpret this statement to mean that the more you include processed carbohydrate in your diet, the more your risk for metabolic disease will rise (if that pattern is maintained over the course of decades). In our chat, I referred to this article I wrote entitled Why dietary fat is fattening and when it’s not, where I referenced the top 10 sources of calories in the US diet. Most of the calories are from processed carbs, but I opine that health status of US citizens would be very different if those calories were from whole-food carbohydrate sources instead.
We also discussed the discrepancy between these findings, with the epidemiological findings that whole grains (for T2DM, and for CVD), especially oats (hat tip Jamie Scott), and fermented dairy are healthy for our metabolisms and blood lipids. Indeed, another point discussed is how the Paleolithic nutrition pattern, while continuing to develop a sterling reputation in clinical trials, may indeed be unnecessarily restrictive. Time will tell, hopefully, but it’s research just like this that will draw more resources and interests to drill down on these important questions and nuances, to help us make increasingly informed nutritional decisions.
A Paleo diet is often thought of as…
- INCLUDED: Vegetables (including root vegetables), fruit (including fruit oils, e.g., olive oil, coconut oil, and palm oil), nuts, seafood, meat, and eggs.
- EXCLUDED: Dairy, grain-based foods, legumes, extra sugar, and nutritional products of industry (including refined fats and refined carbohydrates).
But a better representation of Paleo is more like this…
- INCLUDE: Vegetables (including root vegetables), fruit (including fruit oils, e.g., olive oil, coconut oil, and palm oil), nuts, fish, meat, eggs, and tubers.
- EXCLUDE: Dairy, grain-based foods, legumes, extra sugar, and nutritional products of industry (including refined fats and refined carbohydrates).
And actual health likely stems from this (We’ll call it “Natural Neolithic” of “NatNeo“), but more research is needed.
- INCLUDE: Vegetables (including root vegetables), fruit (including fruit oils, e.g., olive oil, coconut oil, and palm oil), nuts, fish, meat, eggs, tubers, dairy (especially fermented), legumes, and whole grains.
- EXCLUDE: Added sugars and nutritional products of industry (including refined fats, and refined carbohydrates).