Small clinical trial adds to evidence that Stone-Age-style diets can reduce key risk factors for diabetes and cardiovascular disease
by Craig Weatherby
What's up with the idea that it's healthy to eat like a caveman?
Publication of 1995's NeanderThin, by Ray Audette initiated general interest in the potential benefits of the so-called “caveman diet”, high in meat and plant foods and low in grains and starch.
A subsequent book titled The Paleo Diet—by Professor Loren Cordain, Ph.D., of Colorado State University—made a sounder scientific case for eating like prehistoric hominids and humans… such as the Neanderthals and Cro-Magnon man.
The case for eating like a caveman is based on evidence from modern hunter-gatherers, whose diets resemble those of prehistoric ancestors, and from chemical and physical examination of the remains of prehistoric people and their habitats.
From these studies, it is clear that prehistoric hominids and humans ate diets high in wild game (meat and/or fish) and green plants, with no grains and relatively few seeds or starches (largely from tubers).
Scientists call stone-age eating patterns Paleolithic or hunter-gatherer diets, using the terms almost interchangeably due to the diets' similarity.
Let's review the findings of the recent clinical trial, and explore the reasons why eating a Paleolithic diet reduced major heart and diabetes risk factors very rapidly.
Pilot clinical trial affirms healthful impacts of “caveman diet”
Last year, scientists at Sweden's famed Karolinska Institute placed 20 healthy volunteers on a caveman-like diet for three weeks (Osterdahl M et al. 2007).
Before and after the study period, they measured the participants' weight, body mass index, blood pressure, and cholesterol profiles.
The volunteers were then given a list of “caveman” foods they could eat, including fresh or frozen fruit, berries or vegetables, lean meat, unsalted fish, canned tomatoes, lemon or lime juice, spices and coffee or tea without milk or sugar.
Banned foods included any dairy, cultivated or processed foods, such as beans, grains, salt, peanuts, milk, cheese, bread, pasta or rice, sausages, alcohol, sugar, and fruit juice.
However, to keep them from dropping out of the study, the volunteers were allowed to eat up to two potatoes a day and a weekly treat of dried fruit, cured meats and a portion of fatty meat.
At the end of the study, all of the 14 volunteers who completed the diet successfully lost weight, reduced their blood pressure, and slashed blood levels of a clot-causing agent.
These were the average changes (Osterdahl M et al. 2007):
- Lost five pounds.
- Calorie intake dropped by 36 percent.
- Body mass index (BMI) dropped by 0.8 (Healthy BMIs range between 18.5 and 25).
- Systolic blood pressure fell by 3 mmHg.
- Levels of the clotting agent plasminogen activator inhibitor-1 dropped by 72 percent.
The results echo findings in pigs (see below), and support earlier findings that the so-called Paleolithic diet can protect against diabetes.
The only possibly negative effect was a decreased intake of calcium (from dairy foods), which could be a risk factor for osteoporosis later in life.
However recent research virtually proves that when it comes to keeping bones strong, weight bearing exercise and ample vitamin D—from sun exposure and fatty fish—are much more important than calcium. And of course, it's easy to get calcium from pills.
Genetically speaking, we're still cavemen and women
Here's how S. Boyd Eaton, M.D., and Stanley B. Eaton III of Atlanta's Emory University, describe the Stone Age diet and its effect even on modern humans' DNA and consequent responses to various foods:
“Our genome can have changed little since the beginnings of agriculture, so, genetically, humans remain Stone Agers--adapted for a Paleolithic dietary regimen. Such diets were based chiefly on wild game, fish and uncultivated plant foods.
“[Paleolithic diets] … provided abundant protein; a fat profile much different from that of affluent Western nations; high fiber; carbohydrate from fruits and vegetables (and some honey) but not from cereals, refined sugars and dairy products; high levels of micronutrients and probably of phytochemicals as well” (Eaton SB, Eaton SB 3rd 2002).
Two years later, Dr. Cordain—and co-author James O'Keefe, M.D. of the Mid America Heart Institute—came to a similar conclusion:
“Until 500 generations [about 15,000 years] ago, all humans consumed only wild and unprocessed food foraged and hunted from their environment. These circumstances provided a diet high in lean protein, polyunsaturated fats (especially omega-3 fatty acids), monounsaturated fats, fiber, vitamins, minerals, antioxidants, and other beneficial phytochemicals. Historical and anthropological studies show hunter-gatherers generally to be healthy, fit, and largely free of the degenerative cardiovascular diseases common in modern societies” (O'Keefe JH Jr, Cordain L 2004).
In an earlier evidence review, Dr. Cordain and his colleagues noted that American-style Western diets dominated by fatty meat are associated with greater risk of death from cardiovascular disease (CVD).
In contrast, they emphasize that hunter-gatherer societies—who get the majority of their energy from animal food—are relatively free of the signs and symptoms of CVD (Cordain L et al 2002).
They explained that this seeming contradiction is no such thing, based on what we now know about the primary causes of CVD… which do not include high blood cholesterol levels, per se, or diets high in saturated fats (Cordain L et al. 2002):
- Hunter-gatherers' low-starch, high-protein diets—unlike starchy, lower protein Western diets—lower people's blood fat and cholesterol levels.
- Although hunter-gatherers' fat intake equals or exceeds fat intake in Western diets, the Paleolithic diet features important differences* in the type and proportions of fat consumed… characteristics proven to reduce the risk of developing CVD.
- Hunter-gatherers' diets are lower in salt compared with modern Americans' diets, but higher in antioxidants, fiber, vitamins, and beneficial phytochemicals.
*The key beneficial difference may be the human ancient diet's relatively high levels of polyunsaturated plant fats, including omega-6 seed oils and omega-3 leaf/fish oils—and the Paleolithic diet's far lower ratio of pro-inflammatory omega-6 to anti-inflammatory omega-3 fats. While their diets may also have been lower in saturated fats, these are not unhealthful, per se. Oxidation of cholesterol, unhealthy arteries, and fragile heart rhythms are the main cardiovascular risks, and these factors are caused by sedentary lives and empty-calorie diets high in sugars, starches, salt, and fat but low in vegetables, fruits, and fish.
As Dr. Cordain's group wrote, these dietary advantages “…may have operated synergistically with lifestyle characteristics (more exercise, less stress and no smoking) to further deter the development of CVD.”
Some observers have proposed that prehistoric humans might have developed cardiovascular disease had they lived longer than age 30.
But the results of a controlled diet study in pigs—in which some animals were fed grain-heavy human-like diets while their companions ate a diet like those of ancient and modern hunter-gatherer societies—suggest that the Paleolithic diet is inherently heart-healthy.
The authors penned this conclusion to the porcine paper:
“This study in domestic pigs suggests that a Paleolithic diet conferred higher insulin sensitivity, lower C-reactive protein and lower blood pressure when compared to a cereal based diet” (Jönsson T, et al. 2006).
All three of these factors—insulin sensitivity, low C-reactive protein levels, and low blood pressure—are associated with better heart/cardiovascular health.
The lesson seems clear... it's fine to think like a Nobel Prize winner, but it's smart to eat like a Neanderthal.
- Balter V, Simon L. Diet and behavior of the Saint-Césaire Neanderthal inferred from biogeochemical data inversion. J Hum Evol. 2006 Oct;51(4):329-38. Epub 2006 May 5
- Cordain L, Eaton SB, Miller JB, Mann N, Hill K. The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. Eur J Clin Nutr. 2002 Mar;56 Suppl 1:S42-52. Review.
- Eaton SB, Eaton SB 3rd. Paleolithic vs. modern diets--selected pathophysiological implications. Eur J Nutr. 2000 Apr;39(2):67-70.
- Jönsson T, Ahrén B, Pacini G, Sundler F, Wierup N, Steen S, Sjöberg T, Ugander M, Frostegård J, Göransson L, Lindeberg S. A Paleolithic diet confers higher insulin sensitivity, lower C-reactive protein and lower blood pressure than a cereal-based diet in domestic pigs. Nutr Metab (Lond). 2006 Nov 2;3:39.
- 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 Clin Proc. 2004 Jan;79(1):101-8. Review.
- Osterdahl M, Kocturk T, Koochek A, Wändell PE. Effects of a short-term intervention with a Paleolithic diet in healthy volunteers. Eur J Clin Nutr. 2008 May;62(5):682-5. Epub 2007 May 16.
- Richards MP, Pettitt PB, Trinkaus E, Smith FH, Paunovic M, Karavanic I. Neanderthal diet at Vindija and Neanderthal predation: the evidence from stable isotopes. Proc Natl Acad Sci U S A. 2000 Jun 20;97(13):7663-6.
- Richards MP, Taylor G, Steele T, McPherron SP, Soressi M, Jaubert J, Orschiedt J, Mallye JB, Rendu W, Hublin JJ. Isotopic dietary analysis of a Neanderthal and associated fauna from the site of Jonzac (Charente-Maritime), France. J Hum Evol. 2008 Apr 5. [Epub ahead of print]
- Simopoulos AP. Evolutionary aspects of omega-3 fatty acids in the food supply. Prostaglandins Leukot Essent Fatty Acids. 1999 May-Jun;60(5-6):421-9. Review.