The Role of Phytate in Zinc Bioavailability and Homeostasis

作者：Donald Oberleas · 发表于：ACS symposium series · 年份：1983 · DOI：10.1021/bk-1983-0210.ch010 · 被引用次数：34 · 研究领域：Phytase and its Applications、Plant Micronutrient Interactions and Effects、Food and Agricultural Sciences

Phytate, myo inositol hexakis (dihydrogen phosphate) is found in all plant seeds, many roots and tubers. Its synthesis follows pollination and its content increases with maturity. The greatest concentration is found in legume seeds, bran and germ of cereal grains. Small amounts are found in many fruits and vegetables except stem and leafy vegetables. Phytate has been shown to be associated with protein, as magnesium salts in sesame, and is water soluble in corn germ. Phytate complexes with divalent elements with varying degrees of tenacity. The solubility of these complexes varies with pH. Zinc phytate is least soluble at pH 6 and is less soluble than calcium or other mineral complexes at this pH. Kinetic synergism of calcium and zinc with phytate causes a complexation less soluble than either separately. Saliva and pancreatic fluid secrete large quantities of zinc equivalent to as much as three times the dietary intake which is also vulnerable to phytate complexation. The mechanism of phytate action in the gastrointestinal tract is related to complexation and subsequent prevention of absorption and reabsorption of zinc. The complexation can be equated to a phytate:zinc molar ratio and the relative hazard may be subsequently estimated from such data.