Phytic acid humans

In conclusion, phytic acid forms soluble complexes with Ca2+ at intestinal pH under a variety of conditions and fails to inhibit Ca2 bioavailability to mice in our experimental system. Despite the hazard in direct extrapolation of results obtained with animals kept on a well-defined dietary regimen to humans consuming a complex diet, many elements of which affect Ca2+ bioavailability, our data demonstrate the need for a reevaluation of the putative antinutritional properties of dietary phytate. Our further contention that adequate levels of dietary phytate may actually be beneficial due to its food preserving properties and its protection against colonic cancer will warrant a prospective epidemiological human study designed to assess the longterm effects of dietary phytate on mineral bioavailability and inflammatory bowel diseases. 

Phytic acid has been implicated, in both animal and human studies, as having a deleterious effect on the utilization of various minerals and in particular iron and zinc. With reference to zinc, primarily based on results from animal studies, a molar ratio of dietary phytic acid to zinc of 12 to 15 (or greater) has been suggested as a threshold at which decreases in zinc utilization may occur (9.). Results from some recent studies, are summarized in Table II. 

It has generally been presumed and observed (36,42,43), that purified sodium phytate had deleterious effects in humans similar to those observed in animal studies while the effects of indigenous phytic acid have been questioned. Recent results (23,44 Table II) indicate that even with purified sodium phytate, deleterious effects are not always observed. The form of the phytic acid-mineral-protein complex present (12) may be the determinant factor as to whether a deleterious effect is observed. 

Various constituents in plant foods can impede Ca absorption. Plant-based diets can be high in oxalate and phytate, which are recognized as inhibitors of Ca absorption. In fact, Ca absorption is considered to be inversely proportional to oxalic acid content of the food (Weaver et al, 1999). Phytic acid poses Ca absorption problems for those species imable to endogenously synthesize phytase (e.g., humans, birds, and pigs). The Ca in CCM is chelated with the citrate and malate anions, which may make CCM less reactive than other sources of Ca toward food components known to interact with Ca " cations. For example, Lihono et al (1997a) reported data suggesting that the Ca in CCM may be less likely to complex with phytates than other Ca salts. Qn this basis, CCM may be more appropriate for the fortification of soy or other phytic acid-containing products. 

In common with many other legume seeds, raw lentils contain some undesirable constituents, although the levels of these are not likely to be of concern in poultry feeding. Weder (1981) reported the presence of several protease inhibitors in lentils. Marquardt and Bell (1988) also identified lectins (hemagglutinins), phytic acid, saponins and tannins as potential problems but could find no evidence that these had adversely affected performance of pigs fed lentils. It is known that cooking improves the nutritive value of lentils for humans but the effects of consumption of raw lentils by non-ruminants have not been well documented (Castell, 1990). 

In human studies done with leavened and unleavened whole grain bread (7, 19), the conclusions drawn were the same to those drawn for animal studies. The importance of phytic acid was later questioned by the same authors and decreased absorption was described to the fiber content in the diets (20). A negative... 

FIGURE 10,42 Structures of components of the calcium signaling pathway Inositol hexaphosphate (phytic acid) appears not to be synthesized by mammalian cells. The phytic acid in the diet can, to some extent, be hydrolyzed to give inositol. Inositol is required in the diet of rodents but not of humans. 

Tamarind seeds also contain small amounts of anti-nutritional factors such as tannins, phytic acid, hydrogen cyanide, trypsin inhibitor activity and phytohaemaglutination activity, (5). The presence of tannins and other coloring matter in the testa make the whole seeds unsuitable for direct human consumption. Therefore, the testa has to be separated from the kernels by boiling or roasting. Otherwise, side effects such as depression, constipation and gastrointestinal disorders may result (Anon, 1976, cited in (5)). Bhatta et al. (2001, cited in (5)), have considered that a natural source of tannin from tamarind seed husks can be used to depress gas production in mmen fermentation, particularly in crossbred dairy cows. 

Monoferric phytate is the major fraction of iron in wheat bran, and is a highly bioavailable form of dietary iron in contrast to insoluble di- or tetra-ferric phytate. Monoferric phytate equilibrates with the miscible nonheme iron pool of a meal in extrinsic label iron absorption tests. Whole wheat bran depressed absorption by humans of nonheme iron in a meal. Dephytinized wheat bran also inhibited nonheme iron absorption by humans and the inhibition could not be clearly attributed to either the insoluble or soluble fractions of the dephytinized bran. Adult men who consumed 36 g of wheat bran per day had positive iron balances. Iron balance was not increased when dephytinized bran was consumed. The form of ferric phytate must be known to properly explain the effect of phytic acid on iron absorption. The overall meal composition must be considered to evaluate the effect of wheat bran on iron nutrition of humans. 

It does not seem that the human intestinal tract possesses this enzyme. If phytic acid does influence the iron absorption, a parallel is difficult to draw between rats and humans. As in humans the enzyme has not been demonstrated in pigs and, for this reason, pigs were chosen for experimental animals. 

In conclusion, the insoluble fraction, which is by far the main part of cereal dietary fiber, does not bind measurable amounts of ash after digestion with proteolytic and amylolytic enzymes under conditions similar to those in the human gastrointestinal tract. All the binding capacity seems to be due to the small soluble fraction in which the polysaccharides but also most of the phytic acid is recovered. 

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. 

Cereal grains contain high levels of phytic acid. Why is phytic acid an inhibitor of iron uptake by the human body ... 

Calcium forms stable insoluble salt with oxalic acid (see Section 10.2.3.2). In plant cells with higher concentrations of oxalic add, caldum oxalate can be actually present in the form of crystals. Some plants have been shown to bind metals in mixed complexes. For example, chromium can be bound in an oxalate-malate complex, and nickel and zinc can form a dtrate malate complex. Citric add has been proven to be a low molecular weight zinc ligand in human milk, and in casein micelles it binds calcium. It is also used as a food additive (acidulant, synergist to antioxidants and sequestrant), so great attention has been paid to the formation of its complexes with metal ions. The addition to cereal products leads to increased solubihty of naturally present iron, due to its release from phytic acid salts (phytates). 

What is the main function of phytic acid in cereal grains What is the availability of phytic acid for humans and monogastric domestic animals ... 

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