Brain Food

The Protein Power LifePlan
by Michael R. Eades, M.D., Mary Dan Eades, M.D.

(Page 3 of 4)

Not only was meat a principal source of nutrition for developing man, it actually was the driving force allowing us to develop our large brains. For years anthropologists argued that we humans got our large brains because we had to develop them to learn hunting strategies to capture and kill game much larger, faster, and meaner than ourselves. Anthropologists Leslie Aiello and Peter Wheeler turned that idea on its head in a brilliant paper postulating that we were able to develop our large brains not to learn to hunt but because the fruits of our hunting-nutrient-dense meat-allowed us to decrease the size of our digestive tracts. The more nutrient dense the food, the less digestion it needs to extract the nutrients, and consequently the smaller the digestive tract required. (The human digestive tract, while longer than true carnivores, is the shortest of any of the primates.)

Is meat really that nutritionally dense? Let's take a look at a few examples of meat compared to plant foods and see. First, let's look at protein. Protein is the only true essential macronutrient. Fat is also essential, but you can go a lot longer without fat than you can without protein. (Carbohydrates, the third macronutrient, are totally unessential to human health.) So, if you are trying to get protein you could eat 8 ounces of elk meat, a small amount by Paleolithic standards, and get about 65 grams of it. Or you could eat almost 13 heads of lettuce to get the same amount. Or 56 bananas or 261 apples or even 33 slices of bread. If you're trying to get methionine, an essential amino acid that the body uses to make glutathione, its major antioxidant, you could eat the same 8 ounces of elk, or you could eat any of the following: 22 heads of lettuce, 127 bananas, 550 apples, or 46 slices of bread. In almost any nutrient category you want to look at, meat is going to come out a winner because of its incredible nutritional richness that doesn't require much digestive activity to get to.

Table 1.1 shows the difference between the digestive tract of a sheep, which is a true herbivore, and a dog, which is primarily a carnivore, and a human. Let's take a look and see where our species falls in the spectrum from carnivorous to vegetarian traits.

But What If I'm a Vegetarian?

A larger percentage of our patients than you might imagine are vegetarian to some degree. With some modifications, the Protein Power LifePlan works fine for vegetarians, but before we start patients on the vegetarian version we always inquire as to their rationale for following such a diet. If they are vegetarians because they believe it a more healthy way to eat, we disabuse them of that notion quickly. If, on the other hand, they are vegetarians for ideological reasons, we have no quarrel with that and we help them modify our program to solve their health problems within the limits of their ideology. We do, however, encourage them to read a fascinating little book entitled The Covenant of the Wild that goes a long way toward removing many of the inhibitions that some people have about using animals for food.

Were We Hunter-Gatherers or Gatherer-Hunters?

What about the gathering that went along with the hunting? Don't we have a history of a fair amount of plant consumption along with our meat eating? How about the ancient potatoes that went along with our mastodon steak? Until the advent of fire about five hundred thousand years ago, it was fairly difficult for our predecessors to get enough calories from plant foods because the plants themselves fought back by evolving anti-nutrients. Anti-nutrients are chemicals within the plants that bind with the nutrients, making them unavailable for absorption by potential herbivorous predators. (See chapter 6, “The Leaky Gut: Diet and the Autoimmune Response,” for more details.) Often we lose sight of the fact that, like humans and other species, plants evolve, too. The inner goal of plants is to live long, prosper, and disseminate as many seeds as possible in order to propagate the species. If a particular plant is tasty and easy to harvest (we're talking about plants in the wild, not hybrid plants that we put in gardens today), it doesn't last long and certainly doesn't get much of a chance to spread its seeds. Plants, however, that develop (via natural selection) a means to keep from being eaten, whether by growing protective thorns or stickers, acquiring a particularly nasty taste, or producing anti-nutrients, survive to reproduce and multiply. The variety of plant foods available to the vast majority of evolving humans simply wasn't enough to nourish them without a generous amount of meat in the diet. In fact, Cambridge anthropologist Robert Foley says that hunter - gatherers “along with modern agriculturalists . . . are an evolutionarily derived form that appeared towards the end of the Pleistocene [ten thousand or so years ago] as a response to changing resource conditions.” In other words, according to Dr. Foley, gathering, like agriculture, is a recent phenomenon, not a lifestyle that has its roots in several million years of evolution. That said, it's interesting to find, however, that hunter-gatherers (low-fat proponents always want to call them gatherer-hunters) are primarily meat eaters.

Most of the commonly accepted information about hunter-gatherers comes from a paper by R. B. Lee that was presented at a 1968 symposium in Chicago called, strangely enough considering the data presented, “Man the Hunter.” Using the 1967 edition of Murdock's Ethnographic Atlas, a compilation of data about 862 of the world's societies, Lee concluded that the average hunter-gatherer got about 65 percent of his calories from plants and the remaining 35 percent from animals. This paper with its 65:35 plant-to-animal-food ratio has been quoted extensively in both the medical and the anthropological literature and used as the basis for the calculations of the prehistoric diet by innumerable authors who have promoted the idea that the diet of evolving man was mainly plant based. Unfortunately it is incorrect.

A colleague and good friend of ours, Loren Cordain, Ph.D., professor at Colorado State University, one of the world's experts on the Paleolithic diet, and one of the most industrious human beings we've ever known, sensed that there was something not quite right about Lee's paper and decided to investigate the data himself. Dr. Cordain's first clue that something was amiss was unbelievably basic and had been overlooked by all the researchers who had used Lee's paper as the basis of their own work. He simply ran a computerized nutritional analysis of a typical hunter-gatherer diet using the 65:35 plant-to-animal-food ratio. He discovered that for a human to get the calories needed to live on a diet of this nature using plants commonly available to a hunter-gatherer, he would have to gather approximately twelve pounds of vegetation daily, an unlikely scenario, to say the least.

After making this discovery, Dr. Cordain reviewed Lee's original paper and calculations and unearthed some startling facts. Lee only used 58 of the 181 hunter-gatherer societies listed, and he didn't include animal foods obtained from fishing in his calculations. Moreover, he classified the collection and consumption of shellfish as a gathering activity. The Ethnographic Atlas itself considers the collection and consumption of small land fauna (insects, invertebrates, small mammals, amphibians, and reptiles) gathering and categorizes them as such, in so doing ascribing many of the actual animal-derived calories to the plant category.

Dr. Cordain turned to the 1997 update of the Ethnographic Atlas, which represents 1,267 of the world's societies, 229 of which are hunter-gatherers, and did his own calculations. Using all the hunter-gatherer societies listed and putting fishing and shellfish gathering into the appropriate hunter category, he found that the 65:35 values of Lee were flipped. Dr. Cordain calculated the actual plant-to-animal-food ratio to be 35 percent plant, 65 percent animal. He found that the majority of hunter-gatherers throughout the world get over half their subsistence from animal foods, while only 13.5 percent of the world's hunter-gatherers derive more than half their food from gathering plants. And these figures would lean even more in the direction of animal food were it not for the bias built into even the updated Ethnographic Atlas by the inclusion of small animals, reptiles, worms, grubs, etc., in the plant category.

About the Author

Michael R. Eades, M.D., and Mary Dan Eades, M.D. pioneered the field of metabolic medicine. They are on the faculty of Colorado State University in the Department of Health and Exercise Science. They are the authors of Protein Power/i>, which sold over 3 million copies and spent 63 weeks on the New York Times bestseller list, and The Protein Power Lifeplan. Michael R. Eades, M.D. received his engineering degree from California State Polytechnic University and his medical degree from the University of Arkansas. Along with his wife, he has been in the exclusive private practice of bariatric (weight loss) and nutritional medicine for the last 10 years.

More by Michael R. Eades, M.D.

Mary Dan Eades, M.D. received her undergraduate degree in biology and chemistry as well as her medical degree from the University of Arkansas. She joined her husband in the exclusive practice of bariatric and nutritional medicine in 1992, having previously practiced family and general medicine.

More by Mary Dan Eades, M.D.