Paleo Diet

Is the Paleo Diet for You?

Each year, dozens of diets come and go, some for losing weight, others for preventing disease and achieving optimal health. Most are quickly forgotten.

That begs the question: Is there one way of eating that most of us are actually designed for? Could such a diet keep our bodies trim, provide abundant nutrients, and help us stay healthy? The answer is yes.

This diet goes by a variety of names – the Paleolithic diet, the Stone Age diet, and the Ancient Diet. In a nutshell, it’s how our ancient ancestors ate. The rationale is that it’s the best diet for our biological heritage.

Origins of the Paleo Diet Concept

The idea that modern-day people might benefit from ancient eating habits has been debated for decades. But it wasn’t until 1985 that the potential benefits of the Paleolithic diet gained scientific legitimacy with an article in the New England Journal of Medicine. The lead author, S. Boyd Eaton, M.D., of Emory University, made the argument that human genes coevolved with their nutritional milieu over many thousands of years, with our genes and biochemistry becoming dependent on the nutrients in fresh, whole foods. Loren Cordain, Ph.D., of Colorado State University, has also popularized the ancient diet with his book, The Paleo Diet, and numerous scientific articles.

Although you and I are anything but cave men and women, our genes and biochemistry are virtually identical to those of people who lived 50,000 to 10,000 years ago. Eaton and Cordain have explained that modern eating habits – heavy on convenience, fast foods, and junk foods – are incompatible with our genetic heritage. As a result of the collision between ancient genes and modern foods, we are more likely to become overweight and develop diabetes, heart disease, cancer, and many other degenerative diseases.

Both Eaton and Cordain based their research largely on anthropological surveys of 229 pre-technological hunter-gatherer societies and 50 20th-century hunter-gatherer societies (such as the !Kung Bushmen of Africa and the Tasaday of the Philippines) that were still hunting animals, gathering plant foods, and eating much as their ancestors did. These societies were free of modern diseases, often called the “diseases of civilization.”

Of course, ancient eating habits varied by geography and season. The members of landlocked societies hunted for game meat, whereas those near rivers and oceans fished and consumed seafood. In addition, they foraged for vegetables and fruits. Ancient vegetables and fruits tended to resemble roots, kale, berries, seeds, and nuts, rather than today’s highly cultivated, sweeter, and sometimes genetically modified produce. The ratio of animal-to-plant foods varied, with some societies consuming a higher proportion of animal foods and others a greater proportion of plant foods. None of the societies were completely vegetarian, according to both Eaton and Cordain.

In essence, the Paleo diet was the original organic, natural foods diet. Notably absent was the consumption of grains and sugars, with the occasional exception of honey (which was difficult and painful to obtain). People did not consume any bread, muffins, bagels, pasta, pizza, desserts, candy, or soft drinks – no junk foods of any kind.

Our ancestors’ diets began changing around 10,000 years ago with the advent of agriculture and the consumption of grain products (including flour, bread, sugar, and alcohol). Because human teeth cannot effectively chew hard grain seeds, the seeds had to be pulverized (i.e., processed, refined) before consumption. Such processing boosts the glycemic effect of grains, leading to a higher risk of obesity, diabetes, and heart disease.

With the development and widespread consumption of thousands of processed food products over the past 50 to 60 years, our diets have changed more substantially than at any other time over the past 10,000 years – yet 99.99 percent of our genes remain the same as our ancient ancestors. As a consequence, our current dietary habits are a mismatch with our ancient genes and biochemistry. Not surprisingly, two of every three Americans are now overweight or obese, an estimated 100 million have prediabetes, 25 million have type -2 diabetes, and heart disease and cancer are the leading causes of death.

Composition of Ancient Diets

Eaton, Cordain, and other advocates of the Paleo diet contend that we can reduce our risk of disease by eating more like our ancestors. So, what specifically did ancient human diets consist of? Eaton and Cordain’s description of an “average” Paleolithic diet was a composite of many different diets (much the way many people refer to the “average” American diet).

Protein

Animal protein in Paleolithic times provided 19 to 35 percent of calories, which is more than what most Americans currently consume. However, nearly all of the meat was from grass-eating animals, so it was relatively lean and comparable to grass-fed beef or venison.

Plants

Ancient peoples consumed an astonishing variety of plant foods – an average of 100 types of vegetables and fruits over the course of a year. Such a diversity of plant foods provided a wide array of nutrients and antioxidants. Today, most people consume a very narrow range of vegetables, such as iceberg lettuce, potatoes, and peas.

Carbohydrates

People consumed carbohydrates as part of whole foods, including leaves roots, nuts, and seeds. Except for the rare consumption of honey, the carbs were low glycemic.

Fiber

People consumed more than 100 grams of plant fiber daily, compared with an average of less than 20 grams today. As part of the plant matrix, fiber buffered the absorption of carbohydrate calories. According to Eaton, most of the fiber in pre-agricultural diets came from roots, nuts, and fruits, so it did not contain the mineral-inhibiting phytic acid found in grains.

Grains

As they were foraging, ancient peoples might have occasionally consumed tiny amounts of seeds that were the ancestors of modern grains, but they did not consume substantial amounts of grains. Today, refined grains and sugars account for 80 percent of the average American’s calories.

Fats

Paleolithic humans used no cooking oil, so they consumed only the fats naturally found in meat, fish, and vegetables. That resulted in a 1:1 to 4:1 ratio of omega-6 to omega-3 fats, so dietary fats were largely anti-inflammatory. Today’s grain-fed cattle contain a higher percentage of omega-6 and saturated fats. Now, with the widespread consumption of oils from cereal grains (e.g., corn and soy), the omega-6 to omega-3 ratio is at least 20:1, which is pro-inflammatory and disease promoting.

Dairy

With the exception of infants having breast milk, dairy foods were not consumed by ancient peoples. Humans are now the only species on Earth that consume the milk of other species. Many people are sensitive to casein (one of the proteins in cow’s milk) and lactose (one of the sugars in cow’s milk).

Vitamins and minerals

On average, the amount of vitamins and minerals in ancient diets was several times higher than today’s governmental “recommended” amounts. Because foods were not processed, nutrient density was far higher than in today’s foods.

Sodium-potassium ratio

The difference in consumption of sodium and potassium – electrolyte minerals necessary for normal heart function – is especially dramatic. Early humans consumed only an estimated 600 mg of sodium and 7,000 mg of potassium daily. The typical adult American now consumes about 4,000 mg of sodium daily, most of which is added during food processing and before it reaches the table. Potassium consumption is lower than in the past, about 3,000 mg daily.

Adapting Ancient Diets to Our Modern World

Our ancient ancestors’ eating habits established a biological baseline for our current nutritional requirements. But you’re probably thinking, who really wants to eat like a cave man? It’s actually relatively easy to adopt Paleo eating habits with modern foods.

  • Consume a moderate- to high-protein diet. Whenever possible emphasize fish, grass-fed meat, and eggs rich in omega-3 fats.
  • Whether you eat a lot or just a little bit of animal protein, make sure at least half of your plate consists of vegetables and fruits. Diversity is as important as quantity. As a general rule, stick with nonstarchy veggies and fruits and avoid potatoes because of their very high glycemic effect.
  • Limit your intake of grain-based products, particularly wheat, rye, and barley, which are high in a family of proteins known as gluten. Many people are sensitive to gluten, which is also found in many processed vegetarian and vegan foods.
  • Limit your intake of dairy foods because, again, many people are sensitive to them. Whey protein is preferable and less allergenic than casein.
  • Limit your intake of all cooking oils. A little olive oil and butter are better than grain-based oils.
  • Limit your intake of refined sugars and foods rich in them, such as desserts and other sweets.

Adopting a Paleo-style diet can lead to rapid and dramatic improvements in health. Consider a study conducted at Lund University in Sweden, in which researchers asked 29 patients to follow either a Paleo-style diet without grains or a Mediterranean-style diet with grains for three months. All of the patients had advanced heart disease, plus either type-2 diabetes or some other form of glucose intolerance. By the end of the study people eating a Paleo diet had an average 26 percent decrease in blood sugar levels, compared with only a 7 percent decrease among those eating the Mediterranean diet. They also had an average 2-inch decrease in their waistlines, compared with a 1-inch decrease in the Mediterranean diet group.

A modern adaptation of the Paleo diet provides a way of eating that’s consistent with our biology. We can enhance its benefits through careful eating (such as more vegetables) and supplements.

Selected References

Cordain L, Toohey L, Smith MJ, Hickey MS. Modulation of immune function by dietary lectins in rheumatoid arthritis. British Journal of Nutrition, 2000;83:207-217.

Cordain L, Eaton SB, Miller JB, et al. The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. Eur J Clin Nutr, 2002;56 Suppl 1:S42-52.

Eaton SB, Konner M. Paleolithic Nutrition: A consideration of its nature and current implications,” New England Journal of Medicine, 1985;312:283-289.

Eaton SB, Eaton SB III, Konner MJ, et al. An evolutionary perspective enhances understanding of human nutritional requirements. Journal of Nutrition, June 1996;126:1732-40.

Eaton SB, Eaton SB 3rd, Konner MJ. Paleolithic nutrition revisited: a twelve-year retrospective on its nature and implications. Eur J Clin Nutr, 1997;51:207-216.

Eaton SB, Eaton SB 3rd, Sinclair AJ, et al. Dietary intake of long-chain polyunsaturated fatty acids during the paleolithic. World Rev Nutr Diet, 1998;83:12-23.

Lindeberg S, Jonsson T, Granfeldt Y, et al. A Paleolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischemic heart disease. Diabetologia, 2007; 50:1795-1807.

Konner M, Eaton SB. Paleolithic nutrition: twenty-five years later. Nutr Clin Pract, 2010;25:594-602.

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;79:101-108.