Grain Consumption, an Investigation

According to MyPyramid, the new Food Guide Pyramid created by the USDA, a 25 year old male of my height, weight and activity level should be consuming 10oz of grains, half of which should be whole grain, everyday. This amounts to roughly 90grams of carbohydrate, depending on the source, which would constitute 13% of my daily calories, as recommended by MyPyramid. In today's world of endless grain supply, this level of consumption is easily attainable. In fact, I would venture a guess that the majority of us consume far more than our MyPyramid recommended level of grains. Let's face it, a meal just isn't complete unless there is some form of starch in it, and it has always been that way, or at least as far back as written history dictates. Besides, without grains, where would we get all of the carbohydrates that we NEED in our diet for energy?

Without delving deeply into the many reasons why I think that grains are unnecessary, I will instead review Dr. Loren Cordain's research paper "Cereal Grains: Humanity's Double Edged Sword". While the paper is certainly not an exhaustive investigation into the need for grains in the modern human diet, it provides some great insight on the topic.

Introduction

Cordain begins his paper by illustrating just how widespread and overwhelming grain consumption is in the modern world:

....it can be shown that the world’s four major cereal grains (wheat, maize, rice and barley) contribute more tonnage to humanity’s food supply than the next 26 crops combined. Eight cereal grains: wheat, maize, rice, barley, sorghum, oats, rye, and millet provide 56% of the food energy and 50% of the protein consumed on earth.

He uses this data to point out just how dependent man has become on grains, but quickly points out that it hasn't always been that way:

For the vast majority of mankind’s presence on this planet, he rarely if ever consumed cereal grains. With the exception of the last 10,000 years following the agricultural ‘revolution’, humans have existed as non-cereal-eating hunter-gatherers since the emergence of Homo erectus 1.7 million years ago.

Consequently, we have had little time (=500 generations) since the inception of the agricultural revolution 10,000 years ago to adapt to a food type which now represents humanity’s major source of both calories and protein.

This information, combined with the fact that "the human genetic constitution has
changed little in the past 40,000 years" is pretty compelling evidence to me that grains aren't necessary for optimal nutrition. The most common argument against this line of thinking is that Paleolithic Man led a considerably shorter life than modern man. Thankfully, Cordain covers this in his paper "Evolutionary Health Promotion: A Consideration of Common Counterarguments".

Archaeological Perspective

Cordain traces the origins of grain consumption, where-upon he finds that:

Generally, in most parts of the world, whenever cereal-based diets were first adopted as a staple food replacing the primarily animal-based diets of hunter-gatherers, there was a characteristic reduction in stature, an increase in infant mortality, a reduction in lifespan, an increased incidence of infectious diseases, an increase in iron deficiency anemia, an increased incidence of osteomalacia, porotic hyperostosis and other bone mineral disorders and an increase in the number of dental caries and enamel defects.

This observation has been documented in various sources, including "Guns, Germs, and Steel" by Jared Diamond. Also, as in Diamond's book, Cordain discusses how we wouldn't have been able to sustain increasing population densities without the adoption of grains as a staple food source, since they allowed for social stratification and the ability to abandon nomadic lifestyles:

Cereal grains truly represent humanity’s double-edged sword, for without them we likely would not have had an agricultural ‘revolution’. We surely would not be able to sustain the enormous present-day human population (>6 billion), nor would there likely have been societal stratification which ultimately was responsible for the vast technological/industrial culture in which we live. The enormous increase in human knowledge would probably never had taken place had it not been for the widespread adoption of agriculture by humanity, and our understanding of medicine, science and the universe is a direct outcome of the societal stratification wrought by the agricultural ‘revolution’.

Dietary Imbalances of Cereal Grains

We all know that grains are certainly not a nutritional panacea. However, in addition to their obvious shortcomings, Cordain points to other lesser known deficiencies:

Many nutritionists consider cereal grains to be good sources of most of the B vitamins except for vitamin B12... of more importance is the biological availability of the B vitamins contained within cereal grains and their B vitamin content after milling, processing and cooking.

What he demonstrates, which most of us already knew, is that processing grains removes a lot of the vital nutrients contained within them. What most of us don't know, however, is that even if you include the outer coating of the grain (Whole Grain Products), a certain amount of processing and cooking is necessary to make them edible, which diminishes their nutritional content significantly. In addition to that, grains contain certain anti-nutrients that further diminish their nutritional quality:

Corn, like all cereal grains, is rich in antinutrients including lectins which are known to decrease intestinal absorption of many key nutrients.

Because of the high phytate content of whole grain cereals much of the calcium present is unavailable for absorption because the phytate forms insoluble complexes with calcium.

Antinutrients in Cereal Grains

Cordain uses this section to delve deeper into the source of antinutrients and their effect on humans:

...plants face an evolutionary tradeoff; they must grow fast enough to compete, yet they must
also divert enough energy for the synthesis of secondary metabolites required to ward off pathogens and herbivores. Defense is not the only role of secondary metabolites, and other functions include attraction of pollinators, protection from ultraviolet light, structural support, temporary nutrient storage, phytohormone regulation, facilitation of nutrient uptake and protection of roots from acidic and reducing environments.

Cereal grains which are the seeds of grasses (gramineae) contain a variety of secondary metabolites which can be either toxic, antinutritional, benign or somewhere in between, dependent upon the physiology of the consumer animal... Many birds, rodents, insects and ruminants can clearly consume cereal grains in high quantities with minimal undue effects. Because primates evolved in the tropical forest, all of their potential plant food was derived from dicotyledonous species; therefore, the primate gut was initially adapted to both the
nutritive and defensive components of dicotyledons rather than the nutritive and defense components of monocotyledonous cereal grains... Consequently, humans, like all other primates have had little evolutionary experience in developing resistance to secondary
and antinutritional compounds which normally occur in cereal grains.

He then goes on to discuss the many antinutrients present in grains and their potential effects on humans. Most notable of these is:

Lectins - Lectins are proteins that are widespread in the plant kingdom with the unique property of binding to carbohydrate-containing molecules, particularly toward the sugar component. They were originally identified by their ability to agglutinate (clump) erythrocytes which occurs because of the interaction of multiple binding sites on the lectin molecule with specific glycoconjugate receptors on the surface of the erythrocyte cell membranes. Because of this binding property, lectins can interact with a variety of other cells in the body and are recognized as the major antinutrient of food.
The best studied of the cereal grain lectins is wheat germ agglutinin (WGA)
...there is suggestive evidence that high wheat gluten diets induce jejunal mucosal architectural changes in normal subjects without celiac disease.
...Because of their resistance to digestive, proteolytic breakdown, the luminal concentrations of lectins can be quite high, consequently their transport through the gut wall can exceed that of other dietary antigens by several orders of magnitude. Additionally, WGA and other lectins, may facilitate the passage of undegraded dietary antigens into the systemic
circulation by their ability to increase the permeability of the intestine. Consequently, dietary lectins represent powerful oral immunogens capable of eliciting specific and high antibody responses.

The take-home message: Lectins are bad.

Autoimmune Diseases and Cereal Grain Consumption

Cordain attempts to explain the process of autoimmunity (lengthy and wordy), and then links grain consumption to the formation of various autoimmune diseases including Celiac Disease, Insulin-Dependent Diabetes Mellitus, and Rheumatoid Arthritis.

Conclusion

Frankly, after reading the entire paper numerous times, I realized that the majority of the information contained within is relatively useless to the average consumer, especially those of us who consume a supposedly "balanced" diet, and don't have an autoimmune disease. I think that most of the value in it can be obtained from reading just the conclusion. Cordain sums things up well:

From an evolutionary perspective, humanity’s adoption of agriculture, and hence cereal grain consumption, is a relatively recent phenomenon... Cereal grains represent a biologically novel food for mankind, consequently there is considerable genetic discordance between this staple food, and the foods to which our species is genetically adapted.
Cereal grains lack a number of nutrients which are essential for human health and well-being; additionally they contain numerous vitamins and minerals with low biological availability. Furthermore, the inability of humans to physiologically overcome cereal grain antinutrients (phytates, alkylresorcinols, protease inhibitors, lectins, etc.) is indicative of the evolutionary novelty of this food for our species. This genetic maladaptation between human nutrient requirements and those nutrients found in cereal grains manifests itself as vitamin and mineral deficiencies and other nutritionally related disorders, particularly when cereal grains are consumed in excessive quantity. More disturbing is the ability of cereal grain proteins (protease inhibitors, lectins, opioids and storage peptides) to interact with and alter human physiology.
Cereal grains obviously can be included in moderate amounts in the diets of most people without any noticeable, deleterious health effects, and herein lies their strength. When combined with a variety of both animal- and plantbased foods, they provide a cheap and plentiful caloric source, capable of sustaining and promoting human life. The ecologic, energetic efficiency wrought by the widespread cultivation and domestication of cereal grains
allowed for the dramatic expansion of worldwide human populations, which in turn, ultimately led to humanity’s enormous cultural and technological accomplishments. The downside of cereal grain consumption is their ability to disrupt health and well being in virtually all people when consumed in excessive quantity. This information has only been empirically known since the discovery of vitamins, minerals and certain antinutrients in the early part of this century.
Cereal grains are truly humanity’s double-edged sword. For without them, our species would likely have never evolved the complex cultural and technological innovations which allowed our departure from the hunter-gatherer niche. However, because of the dissonance between human evolutionary nutritional requirements and the nutrient content of these domesticated grasses, many of the world’s people suffer disease and dysfunction directly attributable to the consumption of these foods.

From personal experience, I find it much easier to control my body composition when I don't eat grains. Since it is easy to consume too many of them, and they don't provide me with anything that I can't obtain from a more nutritionally dense food source, I don't eat them. Also, since the potential interactions of many of the antinutrients present in grains are not well researched, I would rather not take any chances.