Paleo: Facing the Facts

Paleolithic diets are currently the rage, attracting athletes, dieters, and health seekers of all stripes. The basic premise is simple—the diet humans ate in preagricultural, Paleolithic times is best suited for human health. Whether or not what these relatively short-lived humans ate is what's optimal for the health of today's relatively long-lived humans is a matter of considerable debate. 

Preagricultural diets—which consisted of wild plants, wild animals, and wild fish—varied considerably depending on location, season, hunting and gathering skills, available tools, and so on. People didn't consume oil, sugar, or salt; anything from a box or bag; or the milk of other mammals. Today's new paleo devotees attempt to copy this diet by eating meat, poulty, fish, eggs, vegetables, fruits, nuts, and seeds and avoiding processed foods, grains, legumes, and dairy products. 

Followers of the new paleo diet assume that their nutrient intakes approximate that of Paleolithic humans but their actual intakes may be wide of the mark. Nutritional anthropologists have estimated intakes of cavemen and as it turns out, vegan diets may actually come closer to matching the macro- and micronutrient intakes of Paleolitic diets than new paleo diets. See the Table comparing recommended paleo menus, recommended vegan menus, and a true Paleolithic diet. The data compare three days of recommended paleo menus from a popular paleo website, three days of recommended vegan menus from Ch. 14 in Becoming Vegan, and the estimated average daily intakes of Paleolithic people.

Table: New paleo, true Paleolithic, and vegan diets compared

The comparison shows that this recommended new paleo menu supplies protein, vitamin A, and zinc in amounts closer to a true Paleolithic diet than do the vegan menus. However, its fat and saturated fat levels are about double, cholesterol almost triple, and sodium five times as much as that of a true Paleolithic diet. In addition, the new paleo menue contains about a third of the carbohydrate and fiber and half the vitamin C and calcium of true Paleolithic diets. 

Even 100% plant-based vegan menus deliver fiber in amounts at the lowest end of the estimated Paleolithic intake range; clearly our preagricultural ancestors ate plenty of plants (the only source of fiber). The vegan menu does provide intakes of carbohydrate, fat, saturagted fat, fiber, riboflavin, thiamin, vitamin C, vitamin E, iron, calcium, sodium, and potassium that are closer to the levels supplied by a true Paleolithic diet than do the new paleo menus.

Why are new paleo diets and the true Paleolithic diet so far apart nutritionally? The answer lies in the differences between the meat and vegetables consumed today and those eaten in the Paleolithic era. The wild animals eaten back then provided an estimated 6 to 16% of calories from fat compared to about 40 to 60% in today's domestic animals—even those that are grass-fed. They were also free of hormones, antibiotics, and environmental contaminants. All animal organs were consumed, and insects provided significant amounts of protein. In addition, virtually all fruits and vegetables available in supermarkets are more palatable, more digestible, and easier to store and transport than their wild cousins, at the expense of valuable protective dietary components. Wild or uncultivated plants provide about four times the fiber of commercial plants (13.3g of fiber per 100g versus 4.2g of fiber per 100g, respectively). 

Certainly, there are some benefits to switching from a standard Western diet to a paleo-type diet—highly processed foods, refined carbohydrates, fried foods, and fast foods are eliminated, and fresh fruits, vegetables, nuts and seeds are encouraged. On the other hand, today's paleo eaters tend to include more meat than did early humans, ignoring the impressive evidence linking meat consumption to risk of chronic disease.

Grains and legumes are dispensed with, even though these foods have a long and impressive track record as valuable sources of calories and protein for the world's population. Consumption of legumes and grains is common to all Blue Zone populations (where people live exceptionally long and healthy lives) which validates their place in healthful diets. 

Modern paleo aadvocates claim that these foods weren't part of Paleolithic-era diets, but new research challenges that assumption. They also argue that lectins naturally present in these starchy foods are harmful to human health. Consuming too many lectins can cause significant gastrointestinal distress. However, because legumes and grains are almost always consumed in a cooked forms—and lectins are destroyed during cooking—eating beans and grains doesn't result in lectin overload. Sprouting also reduces lectin level in plants. Generlaly, pea sprouts, lentil sprouts, and mung bean sprouts are safe to consume, as are sprouted grains, which are naturally low in lectins. Most larger legumes contain higher amounts and should be cooked.

The Bottom Line: With its emphasis on eating large quantities of meat, the new paleo diet is a poor imitation of the diets of early humans. Unfortunately, this dietary pattern also ignores the numerous health risks associated with eating meat and the ethical issues that result from an increased demand for food animals. Of the 11 billion animals killed for food ever year in North America, over 95% are raised in factory farm conditions. While new paleo eaters encourage the use of free-range animals, these products are less affordable and less available to the average consumer. Paleo proponents also ignore the looming environmental crisis that makes eating lower on the food chain an ecological imperative. People who try to imitate the diets of our ancestors are forgetting that the world is no longer home to a few million people—instead it must support several billion people. Individuals who want to move closer to a true Paleolithic diet may wish to explore plant-based diets—such diets capture the benefits of eating unprocessed foods without the immense collateral damage.

Source; Davis & Melina, Becoming Vegan: Comprehensive Edition, 279-81 (2014). See also, Becoming Vegan, Express Edition: The Everyday Guide to Plant-based Nutrition (2013)