Grains There are 8 major cereal grains which are consumed by modern man (wheat, rye, barley, oats, corn, rice, sorghum, and millet) each derived from wild precursors. Wheat and barley were domesticated only 10,000 years ago in the Near East; rice approximately 7,000 years ago in China, India, and southeast Asia; corn 7,000 years ago in Central and South America; millets in Africa 5,000-6,000 years ago; sorghum was domesticated in East Africa 5,000-6,000 years ago; rye 5,000 years ago in southwest Asia and oats were domesticated 3,000 years ago in Europe. Modern homo sapiens are present in the fossil record by 50,000 years ago in Australia and by about 40,000 years ago in Europe. The "Agricultural Revolution" i.e. the domestication of animals, cereal grains, and legumes occurred first in the Near East about 10,000 years ago and spread to northern Europe by about 5,000 years. The industrial revolution occurred roughly 200 years ago, and the technological revolution occurred in the past 100 years and has seen enormous growth in the last 50 years. Humans may have eaten these foods for "millennia," but millennia in the overall timeframe of human existence represents 0.4%. Because the estimated amount of genetic change (0.005%) which has occurred in the human genome over this time period is negligible, the genetic makeup of modern man has remained essentially unchanged from that of pre-agricultural man. Consequently, the human genome is most ideally adapted to those foods which were available to pre-agricultural man, namely lean muscle meats, limited fatty organ meats, and wild fruits and vegetables, but significantly, not grains, legumes, dairy products, or the very high-fat meat of modern domesticated animals. The human gut is not equipped with the enzyme systems required to derive energy from the specific types of fibre which predominate in grains. Consequently, unless cereal grains are milled and cooked making them more digestible, the proteins and carbohydrates are largely unavailable for absorption and assimilation. Therefore, until the advent of regular fire use and control 125,000 years ago, it would have been almost virtually energetically impossible for our species to consume cereal grains to supply the bulk of our daily caloric requirements. As has been suggested by John Yudkin (Pure, white and deadly) almost 30 years ago, cereal grains are a relatively recent food for our species and our physiology are still adjusting and adapting to their presence and no human can live on a diet composed entirely of cereal grains (for one thing they have no vitamin C). Eating raw cereal grains as well as cooked cereal grains wreaks havoc on the gut because of the high antinutrient content of grains, to include protease inhibitors, alpha-amylase inhibitors, molecular-mimicking proteins, etc.. When cereal grain calories reach 50% or more of the daily caloric intake, humans suffer severe health consequences. The starch and hence carbohydrate and protein calories in cereal grains occur inside the cell walls of the grain. Because the cell walls of cereal grains are almost completely resistant to the mechanical and chemical action of the human GI tract, cereal grains have been shown to pass through the entire GI tract and appear intact in the faeces. In order to make the nutrients in cereal grains available for digestion, the cell walls must first be broken (by milling) to liberate their contents and then the resultant flour must be cooked. Cooking causes the starch granules in the flour to swell and be disrupted by a process called gelatinisation which renders the starch much more accessible to digestion by pancreatic amylase. It has been shown that the protein digestibility of raw rice is only 25% whereas cooking increases it to 65%. The evolution of new enzyme systems capable of handling novel food types is quite unlikely to have occurred in humans in the short time period since the advent of agriculture. Some populations have had 500 generations to adapt to the new staple foods of agriculture (cereals, legumes, and dairy) whereas others have had only 1-3. Although insulin metabolism is not a direct component of the GI tract, there is substantial evidence to indicate that recently acculturated populations are more prone to hyperinsulinemia and its various clinical manifestations, including type 2 diabetes, obesity, hypertension and coronary heart disease. In conclusion, most of the available evidence shows that except for the evolution of certain disaccharidases and perhaps changes in some genes involving insulin sensitivity, the human gut remains relatively unchanged from paleolithic times. Alessandra Tumolo Www.ttlctrl.co.uk
Posted on: Sat, 15 Jun 2013 08:01:36 +0000
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