Cereal grains: humanity's double-edged sword.

'Here is bread, which strengthens man's heart, and therefore called the staff of life' Introduction The number of plant species which nourish humanity is remarkably limited. Most of the 195,000 species of flowering plants produce edible parts which could be utilized by man; however less than 0.1% or fewer than 300 species are used for food. Approximately 17 plant species provide 90% of mankind's food supply, of which cereal grains supply far and away the greatest percentage (tables 1, 2). From table 1, it can be shown that the world's four major cereal grains (wheat, maize, rice and barley) contribute more tonnage Table 1. The world's top 30 food crops (estimated edible dry matter) Million metric tons 1 Wheat 468 2 Maize 429 3 Rice 330 4 Barley 160 5 Soybean 88 6 20 Cordain 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 [1]. Three cereals: wheat, maize and rice together comprise at least 75% of the world's grain production (table 1). It is clear that humanity has become dependent upon cereal grains for the majority of its food supply. As Mangelsdorf [2] has pointed out, 'cereal grains literally stand between mankind and starvation'; therefore, it is essential that we fully understand the nutritional implications of cereal grain consumption upon human health and well being. Modern man has become so dependent upon eating cereal grains (grass seeds) that it has prompted at least one author [3] to say that we have become 'canaries'. However, this has not always been the case. For the vast majority of mankind's presence on this planet, he rarely if ever consumed cereal grains [4]. 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. Although the first anatomically modern humans (Homo sapiens) appeared in Africa ?90,000 years ago, humans prior to the mesolithic period (~15,000 years ago) like other primates rarely if ever utilized cereal grains [4]. Post-pleistocene (~10,000 years ago) hunter-gatherers occasionally consumed cereal grains; however these foods were apparently not major dietary components for most of the year [5]. It is apparent that there is little or no evolutionary precedent in our species for grass seed consumption …