Paleolithic or Paleo Diet

March 7, 2016


What is the Paleolithic (“Paleo”) diet?

The Paleolithic diet (Paleo or Primal diet) refers to a high protein, low carbohydrate diet associated with hunting animals and gathering plants in the manner of our Paleolithic or Stone Age ancestors.

images-4The Paleo diet recommends consuming:

  • animals, including nearly all of the parts
  • animal products such as honey, eggs
  • specific vegetables like roots, tubers, leaves, flower-tops & stems
  • fruits, raw nuts & seeds
  • sometimes cultured dairy products from pastured animals, & small amounts of pre-soaked legumes, introduced at later stages of the diet

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Why Paleolithic?

Those advocating for the Paleo diet say that humans became superbly adapted to such a diet by 50,000 years ago, and that we should continue to follow this diet to be healthy. They believe humans are poorly adapted to consuming grains associated with agriculture which only developed about 12,000 years ago. They argue that cultured grains and legumes are inherently unhealthy and the cause of many chronic diseases of civilization.

How accurate is this depiction of Paleolithic eating?

Anthropologists have determined that humans have consumed a vast variety of foods for millions of years. People who hunt and gather food eat whatever is available in the environments in which they live. Studies reveal that compared with contemporary humans in North America, our ancestors consumed about three times as much vegetable matter, and they ate meat when and where it was available.

Our ancestors ate:

  • Far more coarse fibre
  • More protein
  • More omega-3 fatty acids
  • More fats (mostly unsaturated)
  • Many more vitamins (including C) and minerals
  • Far less salt & sugarrunning deer
  • Far fewer carbohydrates, especially very few grains

Problems with the Paleolithic Diet

  • Most of the foods that Paleolithic peoples would have consumed are no longer available, and we can only approximate foods recommended in this diet. For lean meat, we would have to eat turkey or farmed game animals; and most of our berries are much larger, contain much more sugar and far less vitamin C, A and essential minerals than wild berries.
  • Many Paleo diets also assume that ancient peoples ate mainly meat to acquire protein, which is not true. Our ancient human ancestors ate what they could get their hands on, and that varied a great deal depending on where they lived. It also changed a great deal through the seasons, and due to many environmental factors beyond their control.  Some ancestral groups relied heavily on plants, others on animals (including many kinds of eggs and insects), and still others on a mix which changed with the seasons. If we can say one thing about their diets, it was diverse! And that’s an important message. Getting plenty of minerals and vitamins is much easier when eating a diversified diet.
  • The paleo diet also assumes that humans have not evolved to digest legumes and grains,  and that eating them can cause what advocates call “diseases of civilization”, such as coronary heart disease, obesity, hypertension, type 2 (adult onset) diabetes, epithelial cell cancers, autoimmune diseases, and osteoporosis. These diseases are rarely seen or simply not found amongst hunter–gatherers and other non-westernized populations. Many people who consume grains and legumes have problems due to the defensive properties that can make them difficult to digest—however, sprouting and soaking them helps to avoid many of these digestive issues.  Recent studies have also shown that in some places eating cereals and grasses is also quite ancient, predating agriculture. How we digest food has also certainly changed and is also related to how we prepare it.  Just under half the human population, for example, has developed the ability to digest dairy foods. And the microbial communities that thrive in our digestive tracts have certainly had plenty of time to evolve into new kinds of colonies. They can do so within our own lifetimes, let alone over thousands of years.

holsteins in field

Studies

Several clinical trials have compared versions of the Paleo diet with other well studied and useful diets to see what the differences might be. Only a few of the studies employed control groups, and all but one used relatively small numbers of people.

In the largest study to date, during a two year long randomized and controlled study of seventy obese, postmenopausal women, researchers looked at the impact of the Paleo Diet in comparison to the Nordic Nutrition Recommendations[2]. Fat was significantly reduced in both groups after six months. But the reduction was much greater in the Paleo diet group. After two years the two groups were not really different, but both had continued to experience some other important changes. The researchers concluded that the Paleo Diet had beneficial effects versus the Nordic Nutrition Recommendations in terms of overall body fat, waist size and triglyceride levels. They noted, however, that after two years, sticking to high protein intake became difficult for some Paleo Diet subjects. So changes in their body size did not always continue, although other healthy changes remained.

In a smaller study[3], researchers did a controlled test with so-called type 2 diabetic and pre-diabetic volunteers with heart disease, comparing one group that consumed a Paleo Diet (in this study, lean meat, fish, fruit, both leafy and starchy root vegetables, eggs and nuts) and another on the popular “Mediterranean Diet” (fish, oils, margarine, low fat dairy products, whole grains and fruit). Both groups improved, but those on the Paleolithic diet improved more and faster.

Many people find that Paleo dietary regime is quite satiating, meaning that people feel full and are likely to stick to it for longer periods of time than some other diets. In the one long term study, after several years, significant numbers re-gained weight, although they did not gain even more weight. This means that one of the worst attributes of many diets—rebound and increased weight gain after dieting—may be avoided when people follow the Paleo diet recommendations. More long term studies are required before this finding can be confirmed.

Conclusion

Although the rationale for the paleolithic diet is overly simplistic, it still is certainly better for us than the high simple carbohydrate and sugary diet that is now so common. It seems to reduce the severity of some serious problems associated with many cardiovascular diseases, particularly through positive changes to insulin resistance. These problems include: diabetes (type 2), abdominal obesity, high blood pressure, elevated cholesterol, fatty liver (a precursor of cirrhosis and perhaps liver cancer), atherosclerosis associated with coronary artery disease, strokes and peripheral vascular disease. There is also an association with a number of abnormal growths related to high levels of circulating insulin because insulin is actually anabolic hormone which promotes growth. These problems include various skin lesions and polycystic ovary syndrome, male pattern hair growth on women, and overall increased growth and “coarser” features.

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Bibliography
[1] Carrera-Bastos, Pedro , Maelan Fontes-villalba, James H O’Keefe, Staffan Lindeberg and Loren Cordain. The western diet and lifestyle and diseases of civilization. Research Reports in Clinical Cardiology 2, 15-35 (2011).

[2] C Mellberg, S Sandberg, M Ryberg, M Eriksson, S Brage, C Larsson, T Olsson and B Lindahl. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial, European Journal of Clinical Nutrition 68, 350-357 (March 2014) | doi:10.1038/ejcn.2013.290

[3] Lindeberg S, et al. A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia 50, 1795-1807 (2007).