Over the weekend I spent some time looking at the evidence in the area of ‘primal’ or ‘Paleolithic’ eating. I was aware, I think, of much of the evidence in this area (and I’ve even reported on relevant studies here and here), but it seems I missed a quite-important study that I am going to report here.
The study, published in 2009 in the journal Cardiovascular Diabetology . In this study, 13 men and women with type 2 diabetes ate, on separate occasions, two different diets, each for three months. One diet was a typical ‘diabetes diet’, rich in carbobydrate. The other was a ‘primal’ or “Paleolithic’ diet based on foodstuff resembling those that humans ate prior to the introduction of agriculture and animal husbandry some 10,000 years ago. Here are the details of these diets:
The information on the Diabetes diet stated that it should aim at evenly distributed meals with increased intake of vegetables, root vegetables, dietary fiber, whole-grain bread and other whole-grain cereal products, fruits and berries, and decreased intake of total fat with more unsaturated fat. The majority of dietary energy should come from carbohydrates from foods naturally rich in carbohydrate and dietary fiber. The concepts of glycemic index and varied meals through meal planning by the Plate Model were explained. Salt intake was recommended to be kept below 6 g per day.
The information on the Paleolithic diet stated that it should be based on lean meat, fish, fruit, leafy and cruciferous vegetables, root vegetables, eggs and nuts, while excluding dairy products, cereal grains, beans, refined fats, sugar, candy, soft drinks, beer and extra addition of salt. The following items were recommended in limited amounts for the Paleolithic diet: eggs (≤2 per day), nuts (preferentially walnuts), dried fruit, potatoes (≤1 medium-sized per day), rapeseed or olive oil (≤1 tablespoon per day), wine (≤1 glass per day). The intake of other foods was not restricted and no advice was given with regard to proportions of food categories (e.g. animal versus plant foods). The evolutionary rationale for a Paleolithic diet and potential benefits were explained.
Compared to the diabetes diet, the Paleolithic diet led to individuals eating an average of about 300 calories less each day. This likely reflects the ability of primal, lower-carb diets to sate the appetite more effectively than ‘healthy’ diets richer in carbohydrate. For more on this, see this recent post.
Overall, the Paleolithic diet brought improvements in a range of health measures and markers compared to the diabetes diet. Specifically:
- An additional 3 kg reduction in weight
- A reduction in triglyceride levels (high levels of triglyceride are linked with increased risk of cardiovascular disease)
- Reduced diastolic blood pressure (the lower of the two blood pressure readings)
- 4 cm reduction in waist circumference
- Lower levels of HbA1c (measure of blood sugar control over the preceding 3 months or so)
- Increased levels of HDL cholesterol (the form of cholesterol associated with reduced risk of cardiovascular disease)
In other words, the Paleolithic diet, compared to standard diatetic advice for diabetes, led to significant improvements in markers for diabetes and cardiovascular disease.
Some of these benefits might be related to the fact that, on the ‘Paleo’ diet, individuals ate less. But ate less of what? Daily consumption (in grams) of protein, carbohydrate and fat in the paleo diet and carbohydrate diet were:
Protein: 94 and 90
Carbohydrate: 125 and 196
Fat: 68 and 72
In other words, the Paleo diet contained a little more protein and a little less fat, but the major difference was a lot less carbohydrate.
There is a common notion that when individuals go ‘low-carb’, they end up eating a tonne of protein and fat. This study actually reflects what tends to happen in reality: individuals don’t end up doing that at all, they just eat less carbohydrate. And the typical results of this are, in this study, here for all to see.
1. Jönsson T, et al. Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovasc Diabetol. 2009;8:35.