(NaturalNews) A large body of evidence exists that shows that eating the entire grain rich in phytic acid may lead to losses in zinc, iron, vitamin C and fat-soluble vitamin D. Part of the solution to this plant toxin is to disable phytic acid with the enzyme phytase.
Phytase is the enzyme that neutralizes phytic acid and liberates the phosphorus. This enzyme co-exists in plant foods that contain phytic acid. Ruminant animals such as cows, sheep and goats have no trouble with phytic acid because phytase is produced by rumen microorganisms. Mice produce thirty times more phytase than humans,(F-1) so they can be quite happy eating a raw whole grain diet. But data from experiments on phytic acid using mice and other rodents cannot be applied to humans. In general, humans do not produce enough phytase to safely consume large quantities of high-phytate foods on a regular basis. However, probiotic lactobacilli, and other species of digestive microflora, can produce phytase. Increased production of phytase by the gut microflora explains why some people can adjust to a high-phytate diet.
Sprouting activates phytase, thus reducing phytic acid.(F-2) The use of sprouted grains will reduce the quantity of phytic acids in animal feed, with no significant reduction of nutritional value.(F-3) But that does not mean that sprouting is sufficient to make whole grains safe for human consumption. Soaking grains and flour in an acid medium at very warm temperatures (between 75-95 degrees Fahrenheit), as in the sourdough process, also activates phytase and reduces or even eliminates phytic acid.
Before the advent of industrial agriculture, farmers typically soaked crushed grain in hot water before feeding it to poultry and hogs. Today, feed manufacturers add phytase to grain mixes to get better growth in animals.
Not all grains contain enough phytase to eliminate the phytic acid, even when properly prepared. For example, corn, millet, oats and brown rice do not contain sufficient phytase to eliminate all the phytic acid they contain even when you soak, sour or sprout them. On the other hand, wheat and rye contain high levels of phytase. Wheat contains fourteen times more phytase than rice, and rye contains over twice as much phytase as wheat.(F-4) Soaking or souring these grains, when freshly ground, in a warm environment will destroy all of the phytic acid. The high levels of phytase in rye explain why this grain is preferred as a starter for sourdough breads. Phytase is destroyed by steam heat at about 176 degrees Fahrenheit in ten minutes or less. In a wet solution, phytase is destroyed at 131-149 degrees Fahrenheit. (F-5) Thus heat processing, as in extrusion, will completely destroy phytase - think of extruded all-bran cereal, very high in phytic acid and all of its phytase destroyed by processing. Extruded cereals made of bran and whole grains are a recipe for digestive problems and mineral deficiencies!
Phytase is present in small amounts in oats, but heat treating to produce commercial oatmeal renders it inactive. Even grinding a grain too quickly or at too high a temperature could destroy phytase, as will freezing and long storage times. Fresh flour has a higher content of phytase than does flour that has been stored.(F-6) Traditional cultures generally grind their grain fresh before preparation. Weston Price found that mice fed whole grain flours that were not freshly ground did not grow properly.(F-7)
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References 1. Iqbal TH and others. Phytase activity in the human and rat small intestine. Gut. 1994 September 35(9):1233-1236. . 2 Malleshi NG. Nutritive value of malted millet flours. Plant Foods for Human Nutrition 1986 3. Whole Grains and Tooth Decay 4. Egli I and others. The Influence of Soaking and Germination on the Phytase Activity and Phytic Acid Content of Grains and Seeds Potentially Useful for Complementary Feeding. Journal of Food Science 2002 Vol. 67, Nr. 9. 5. Peers FG. Phytase of Wheat. The Biochemical Journal 1953 53(1):102-110. 6. Campbell J and others. Nutritional Characteristics of Organic, Freshly stone-ground sourdough and conventional breads. http://eap.mcgill.ca/publications/EAP35.htm. 7. Weston Price Nutrition and Physical Degeneration. Price-Pottenger Nutrition Foundation. 8th edition, page 249