Back then grains made up around 40-60% of my diet.
Despite containing magnesium, wheat, including whole wheat, can actually deplete magnesium in humans and is one of the main culprits in the epidemic of magnesium deficiency in the US. Undigested grain phytates interfere with the utilization of folic acid, riboflavin, iron, zinc, calcium, magnesium, copper, manganese and proteins, resulting in severe nutrient deficiencies in humans who eat too much unfortified grains (before grain fortification, nutrient deficiency diseases and disorders were widespread even among Western nations). The phytates and other proteins in the grains also have stuctures similar to pathogenic viruses and bacteria, which can trigger autoimmune disorders in humans, resulting in damage to organs and other ill effects. Even fortified grains can contribute to nutrient-depletion, malabsorption and autoimmune disorders, particularly in people with high levels of genetic susceptibility, high intake of grains, or long-term intake of grains. One common effect is damage to the epithelial layer in the small intestine, which reduces its ability to absorb nutrients and increases its permeability to toxins such as the very same phytate antinutrients, as well as gluten proteins, opioids and other damaging molecules.
Some sources:
"...the bioavailability of zinc, copper and magnesium in cereal grains is generally low [75], whereas the absorption of manganese, chromium and selenium does not appear to be impaired [90]. Except for zinc, the clinical implications of deficiencies in these minerals relative to cereal grain consumption have been poorly studied. Consequently, few links have been established between high cereal grain consumption and deficiencies of copper, magnesium, manganese, chromium and selenium in human diets. However, there is substantial evidence which demonstrates that relatively high consumption of cereal grains can have a detrimental influence upon zinc metabolism and thus adversely affect human health and well-being." (Cereal Grains: Humanity's Double-Edged Sword, Loren Cordain,
http://www.ncbi.nlm.nih.gov/pubmed/10489816)
"The well-documented phytates of cereal grains sequester many divalent ions including calcium, zinc, iron, and magnesium, which can impair bone growth and metabolism. Further, there are antinutrients in cereal grains which directly impair vitamin D metabolism [Batchelor 1983; Clement 1987]; and rickets are routinely induced in animal models via consumption of high levels of cereal grains [Sly 1984]." (The Late Role of Grains and Legumes in the Human Diet, and Biochemical Evidence of their Evolutionary Discordance, by Loren Cordain, Ph.D., 1999,
www.beyondveg.com/cat/paleodiet/index.shtml)
See also PHYTASES, ACIDES NUCLÉIQUES LES CODANT ET LEURS PROCÉDÉS DE PRODUCTION ET D'UTILISATION,
http://www.wipo.int/pctdb/fr/ia.jsp?ia=US2007%2F079187&IA=US2007%2F079187&DISPLAY=DESC
