Vegetables not in season
It’s quite difficult to know exactly what early humans ate 100,000 years ago. Scientists use a variety of methods to investigate, including analysis of patterns of wear on teeth, searches of prehistoric dwellings, and analysis of carbon isotopes in organic matter.
Some of the best-preserved human prehistoric artifacts are found in caves, which protected them from environmental degradation. That’s why the paleo diet is sometimes called the caveman diet.
We have an inkling of what foods were available in specific climates and regions. We have some ideas about tools our ancestors had available to hunt, gather, and process foods. Perhaps most reliably, we have fairly good data on what modern hunter-gatherer groups eat (for those few still in existence) or ate (for those lately extinct or modernized).
The Paleolithic Versus Typical Modern Western Diet
Today we get most of our calories from grains, sugars, domesticated livestock, and dairy products. On the other hand, our pre-agricultural ancestors ate primarily wild game and naturally occurring plant foods. Their carbohydrates would have come from fruits and vegetables rather than cereal grains, diary products, and refined sugars. They ate no junk food, no industrial seed oils, and very few grains and dairy products. Compared to us, they ate more potassium, fiber, protein, and micronutrients, but less sodium and carbohydrate. They ate relatively more omega-3 fatty acids and less omega-6s. Paleo dieters today aim to consume natural whole foods while minimizing simple sugars and refined starches. The paleo community generally is convinced that grains and legumes are harmful, while others disagree. Dairy products are allowed in some versions of paleo, although purists would vote against. Now let’s dig into the details.
The Eaton and Konner Model
S. Boyd Eaton and Melvin Konner in 2010 looked carefully at the diet of pre-industrial hunter-gatherers and proposed a prototypical ancestral diet. Note that actual diet would vary with climate, latitude, altitude, water availability, etc. Eaton and Konner suggest our ancestral diet looked like this:
- Carbohydrates: 35-40% of daily energy (calories)
- Protein: 25-30% of daily energy
- Fat: 20-35% of daily energy
- Added sugar: 2% of daily energy
- Fiber: over 70 g/day
- EPA and DHA*: 0.7-6 g/day
- Cholesterol: 500+ mg/day
- Vitamin C: 500 mg/day
- Vitamin D: 4,000 IU/day (sunlight)
- Calcium: 1,000-1,500 mg/day
- Sodium: under 1,000 mg/day
- Potassium: 7,000 mg/day
*Eicosapentaenoic acid and docosahexaenoic acid (omega-3 fatty acids)
Their conception of a modern Paleolithic food pyramid is a base of high-fiber vegetables and fruits, the next tier up being meat/fish/low-fat dairy (all lean), then a possible tier for whole grain (admittedly very unusual), with a small peak of oils, fats, and refined carbohydrates. Their inclusion of dairy products and whole grains must be a concession to convenience and the reality that those items can be healthful for modern humans. Eaton and Konner note that hunter-gatherer groups had a high degree of dependence on plant foods, while obtaining 35 to 65% of diet (calories rather than weight, I assume) from animal flesh. They found some modern hunter-gatherer cultures deriving as much as 65% of calories from carbohydrate (mostly plants, then). It’s a mistake to assume that the typical Paleolithic diet is necessarily meat-based, as the popular press so often describes it.
Eaton and Konner make a few other distinctions that are worth mentioning now. Game animals have more mono- and polyunsaturated fatty acids than supermarket meat. The Paleolithic diet’s ratio of omega-6 to omega-3 fatty acids was about 2:1, in contrast to the modern Western ratio of 10:1 or even higher.
I’d like to share a few more tidbits from their 2010 article:
- The transition from hunting/gathering to farming (about 10,000 year ago) saw a decrease in body size and robustness, plus evidence of nutritional stress.
- Levels of muscular and aerobic fitness in ancestral groups are much higher than modern societies, with a concomittant higher level of calorie consumption.
- Average life expectancies in pre-industrial hunter-gatherer (H-G) groups was only 30-35 years, but much of this low number simply reflects high infant and child death rates.
- H-G deaths overwhelmingly reflect infectious diseases.
- H-G groups had a high degree of dependence on plant foods.
- Fish and shellfish are more important food sources than these authors thought 25 years earlier.
- H-G diets are higher in fat and protein than they once thought. • Nearly all H-G carbs are from vegetables and fruits, which have more favorable glycemic responses (i.e., a lesser rise in blood sugar) than grains and concentrated sugars.
- Uncultivated or wild fruits and vegetables have much more fiber than commercial ones (13 versus 4 g fiber per 100 g of food).
The Diet-Heart Hypothesis is the idea that dietary total and saturated fat, and cholesterol, cause or contribute to atherosclerosis (hardening of the arteries), leading to heart attacks and strokes. Konner and Eaton still believe (in 2010 at least) the theory is valid for fats, but not cholesterol. The latest evidence, however, is that even total and saturated fat are minimally or unrelated to atherosclerosis. They also believe total fat, due to its caloric load, is an important contributor to obesity and type 2 diabetes. I agree that may be true, especially if you eat a lot of carbohydrates with fat. To further imitate the Paleolithic lifestyle, Eaton and Konner also recommend high activity levels, including resistance exercise, flexibility, and aerobics, burning over 1,000 calories daily exclusive of resting metabolism. (Reference: Konner, Melvin and Eaton, S. Boyd. Paleolithic Nutrition: Twenty-Five Years Later. Nutrition in Clinical Practice, 25 (2010): 594-602. doi: 10.1177/0884533610385702) But let’s not put all our eggs in the Eaton and Konner basket.
That exposed skin makes vitamin D
The Kuipers Model
A 2010 scientific article by Kuipers et al suggests that the East African Paleolithic diet derived, on average, 25-29% of calories from protein, 30-39% from fat, and 39-40% from carbohydrate. That qualifies as mildly low-carb, and similar to Eaton and Konner’s macronutrient breakdown. Modern Western percentages for protein, fat, and carb are 15%, 33%, and 50%, respectively. Kuipers et al suggest that the evolution of our large brains in East Africa may have been possible by utilization of aquatic resources such as fish, lobster, crab, shrimp, sea urchins, squid, octopus, and amphibians. Rather than savannah, this was a land-water ecosytem. Diets here would have been rich in the omega-3 fatty acids (EPA and DHA) we find in fish oil. Kuipers believes roots and tubers were also part of the Paleolithic diet. (Reference: Kuipers, R., et al (L. Cordain and S. Eaton are co-authors) (2010). Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet British Journal of Nutrition, 1-22 DOI: 10.1017/S0007114510002679)
The Cordain Model
Loren Cordain and associates in 2000 suggested that Paleolithic diets derived about a third—22 to 40%—of calories from carbohydrate, based on modern hunter-gatherer societies. The lower carb consumption compared to Western diets left more room for moderate to high amounts of protein and fat. Dr. Cordain is a co-author with Eaton and Konner on many paleo diet scientific articles, so they don’t have many differences. (Reference: Cordain, L., et al. Plant-animal subsistance ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. American Journal of Clinical Nutrition, 71 (2000): 682-692.)
Dr. Cordain (Ph.D.) is probably the preeminent scientist who advocates the Paleolithic diet. He’s made a few modifications in his model diet over the years. From his website in 2014, the following are the seven pillars of his conception of the modern paleo diet compared to the typical Western diet. The paleo diet is:
- higher in protein (25-30% of calories versus 15%)
- lower in carbohydrates and glycemic index via nonstarchy fresh fruits and vegetables
- higher in fiber
- moderate to high fat content, especially monounsaturated fats and polyunsaturated fats (particularly omega-3 fatty acids)
- higher in potassium and lower in sodium
- higher dietary alkaline load relative to acid load (vegetables and fruit counteract the acid in meat and fish)
- higher in many vitamins, minerals, antioxidants and plant phytochemicals
Salmon is a great source of omega-3 fatty acids
Carbohydrate Content of the Paleo Diet
Since dietary carbohydrates are major contributors to blood sugar, the carbohydrates in the Paleolithic diet are important. It appears that the average paleo diet derived a little over a third of calories from carbohydrate: that qualifies as low-carb since the average Western diet provides half of calories as carbohydrate. The carbohydrates eaten by Paleolithic man were accompanied by lots of fiber, over four times as much as the average American diet (70+ grams versus 15 grams). The sources of carbohydrate were fruits, vegetables, and roots or tubers, with minimal and seasonal contribution from honey. Fiber is important since high consumption is linked in modern times to lower rates of type 2 diabetes, and fiber also slows and limits the rise in blood sugar after meals. Furthermore, the original Paleolithic carbohydrate sources generally would have been much less calorically dense than modern carbohydrates sources. For instance, one Frosted Strawberry Pop-Tart has the same amount of calories (200) as four cups of fresh strawberry halves, but the Pop-Tart has less than one gram of fiber compared to 12 gm in the raw berries.
We Can’t or Won’t Re-Create a True Paleolithic Diet
Because of our modification of edible plants and animals, it’s impossible for most of us to accurately recreate the diet of our Paleolithic ancestors. The closest you could come would be to live entirely off the land, catching or hunting wild animals and foraging for wild plants. That’s a heck of a lot of work, and wouldn’t sustain more than a tiny fraction of the planet’s current seven billion souls. If we’re going to construct a modern Paleolithic-style diet, now we’ve got some anchoring numbers.
Steve Parker, M.D.