Phytic acid magnesium

Much of the current research has centered upon the role of phytic acid on zinc and iron bioavailability (110-124). Work performed at the authors institution with several different types of soy foods suggests that phytic acid is a major factor affecting availability of zinc from foods derived from the legume (110-114). In addition, it appears that endogenous zinc in high-phytate foods may be a limiting factor in optimal utilization of these foods for man. We have found that fortification of soy foods (under proper conditions) with zinc, iron, magnesium, or calcium results in excellent... 

Soybean meal is generally low in minerals and vitamins (except choline and folic acid). About two-thirds of the P in soybeans is bound as phytate and is mostly unavailable to animals. This compound also chelates mineral elements including Ca, magnesium, potassium, iron and zinc, rendering them unavailable to poultry. Therefore, it is important that diets based on soybean meal contain adequate amounts of these trace minerals. Another approach to the phytate problem is to add phytase, a phytic acid degrading enzyme, to the feed to release phytin-bound P. A benefit of this approach is that less P needs to be added to the diet, reducing excess P loading into the environment. 

The ash content of soybeans is relatively high, close to 5 percent. The ash and major mineral levels in soybeans are listed in Table 5-7. Potassium and phosphorus are the elements present in greatest abundance. About 70 to 80 percent of the phosphorus in soybeans is present in the form of phytic acid, the phosphoric acid ester of inositol (Figure 5-5). Phytin is the calcium-magnesium-potassium salt of inositol hexaphosphoric acid or phytic acid. The phytates are important because of their effect on protein solubility and because they may interfere with absorption of calcium from the diet. Phytic acid is present in many foods of plant origin. 

Our work with soy products indicates that extrinsic zinc is more available than intrinsic zinc. The intrinsic and extrinsic zinc pools do not completely mix in all soy products. Phytic acid is an inhibitor of zinc bioavailability and this inhibition is aggravated by higher levels of dietary calcium and perhaps magnesium. Neutralization of soy isolates and concentates, with subsequent drying, reduces zinc utilization for rats. 

Plant foods contain relatively large amounts of inositol phosphates, including the hexaphosphate, phytic acid. Phytate chelates minerals, such as calcium, zinc, and magnesium, forming insoluble complexes that are not absorbed. However, both intestinal phosphatases and endogenous phosphatases (phytase) in many foods dephosphorylate a significant proportion of dietary phytate. The inositol released can be absorbed and utilized for phosphatidylinositol synthesis. 

Both the glycolipids and the phospholipids of corn have lower percentages of linolenic acid (18 3) and are more saturated than those in the soybean. In general, cmde corn and soybean lecithins are equal in linoleic acid (18 2) content, but lino-leic acid in corn varies from 42% to 70% depending on the variety of corn. Phytic acid, 88% of which is in the com germ, is extracted as part of the lecithin fraction (32, 37). Elimination of phytic acid in com is desirable because it binds zinc, magnesium, and calcium. 

Phytate is the calcium, magnesium or potassium salt of phytic acid, which is inositol hexaphosphoric acid (Fig. 10.9). More than half of the total phosphorus in soybeans is in the form of phytic acid (Liu, 2004a). Because of its chelating power, phytic acid makes many essential minerals in soybeans or in diets unavailable for absorption and utilization for both human and domestic animals thus phytic acid is known as an anti-nutritional factor. 

Organic phosphorus compounds, primarily inositolhexaphosphates (probably more than 50% of all organic phosphates), occiu in soils. The parent cyclic polyol, inositol, exists in numerous stereoisomeric configurations, of which myo-, scyllo-, neo-, and cZZ-inositol have been isolated from soils as phosphate esters. The hexaphosphate of myoinositol (myo-IHP), phytic acid, occurs in plant tissues. It often occurs as phytin, the calcium magnesium salt. Esters of myo-IHP are readily adsorbed in acidic soil solution by clay minerals and finely divided hydrated oxides of iron and aluminum. Organic sulfur compounds present in soils probably occur primarily as amino acids—e.g., cysteine, cystine, and methionine. 

One compound around which there is notable ambiguity is myo-inositol hexa-kisphosphate. This commonly occurring organic phosphate is also known as phytic acid, although the term phytate is used for salt forms, and phytin is sometimes used to refer specifically to the calcium-magnesium salt. To avoid ambiguity, the term myoinositol hexakisphosphate is used throughout the book, unless reference is made to a specific salt form (e.g. calcium phytate). 

Brazil nut contains small amounts of other minor bioactives and essential micronutrients such as essential minerals, phytic acid, dietary fiber, and thiamin. Brazil nut is an excellent source of magnesium, potassium, and calcium. 

Phytic acid occurs as a calcium or magnesium salt in dried peas, beans, husks and cereal grains. Phytates accumulate in seeds and up to 90% of the seed phosphate can be in this form. About 75% of the phosphorus in soy beans is present as phytate. 

Phytic acid, myo-inositol hexakis (dIhydrogen phosphate), as-l,2,3,S-tnns-4,6-cyclohexanehexol-hexaphosphate a major phosphate storage compound in plants, which is especially abundant in oil seeds, legumes and cereal grains. It is the hexaphosphate of A/yo-inositol (see), in which each OH-group of myoinositol is esterified with phosphoric acid. Calcium and magnesium salts of P.a. are known as phytin. The commercial preparation of myo-inositol involves extraction of P. a. from com (maize) steep liquor, hydrolysis of the P.a. to myo-inositol and inorganic phosphate, and crystallization of the myo-inositol from water. 

Phytin, the insoluble mixed potassium, magnesium and calcium salt of myoinositol hexaphosphoric acid (phytic acid) is the major storage form of phosphate and macronutrient mineral elements in seeds. It is invariably present within a globoid in protein bodies [38, 45, 47, 56, 68, 69, 71]. 

Phosphate is stored in the mature seed as phytic acid, which is the hexaphospho-ric ester of myo-inositol —see Chapter 2. This combines with potassium, calcium and magnesium to form the salt called phytin. Accumulation of phytin in cereals is almost exclusively in the aleurone grains of the aleurone layer where it is deposited as a discrete globoid in association with protein. The precise mechanism of phytin deposition and the enzymes involved therein have been little studied and will receive no more attention here. The importance of phytin as a phosphate reserve is discussed in Chapter 6. 

Phytic acid and some components of dietary fibre also reduce the resorption of magnesium and some other elements from the diet (especially iron and zinc). A higher protein content in the diet increases the resorption of calcium. 

Phytic acid (myo-inositol-l,2,3,4,5,6-hexakisdihydrogen phosphate) occurs in a number of important crops, especially cereals, legumes and oilseeds. The main form is a mixed calcium and magnesium salt, which is called phytin. Phytate phosphorus has reduced biological utihsation and lower utihsation than other minerals (Ca, Mg and Zn and Fe in particular). The contents of phytic acid in some food materials and foods, and the ratio of phytate phosphorus to total phosphorus, are shown in Table 6.5. 

Phytic acid,myo-inositol-l,2,3,4,5,6-hexakisdihydrogenphosphate, is the main storage form of phosphorus used during germination of seeds of cereals, pulses and oilseeds. Phytic add in seeds occurs primarily as a mixed calcium and magnesium salt, which is called phytin. Insoluble salts and ones that are utilised only slightly are also produced with other di- and trivalent ions, such as Fe and Zn in particular. The issue of phytin is discussed in detail in Chapter 6 (see Section 6.3.4.2.1). 

X. Cui, Y. Li, Q. Li, G. Jin, M. Ding and F. Wang, Influence of phytic acid concentration on performance of phytic acid conversion coatings on the AZ91D magnesium alloy . Materials Chemistry and Physics, 111, (2008), 503-507. 

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