Phytic acid copper

If one had to state an overall role of copper in the body, one might say oxygen metabolism. One major factor shared by both zinc and copper is that both metal ions occur bound to metallothionein. The function of metallothionein is not firmly established. Copper is bound to another protein, ceruloplasmin, which occurs in the cell and plasma. The function of this protein is not clear either. Zinc absorption, as iron absorption, is impaired by high levels of phytic acid. Copper absorption is not inhibited by phytic acid. The major route of excretion of both metal ions is fecal, rather than urinary. 

Heretofore, no economical method for preparing pure phytic acid was known. The classical method was to dissolve calcium phytate in an acid such as hydrochloric acid, and then add a solution of a copper salt, such as copper sulfate to precipitate copper phytate. The latter was suspended in water and treated with hydrogen sulfide, which formed insoluble copper sulfide and released phytic acid to the solution. After removing the copper sulfide by filtration, the filtrate was concentrated to yield phytic acid as a syrup. 

Copper(II) oxide and cobalt(II) hydroxide form cements with solutions of many multifunctional organic acids propanetricarboxylic acid, tartaric acid, malic acid, pyruvic acid, mellitic acid, gallic acid, tannic acid and phytic acid (Allen et al., 1984 Prosser et al., 1986). These have been used mainly in cement devices for the sustained release of copper and cobalt (Manston et al., 1985 Mansion Gleed, 1985). Little is known about... 

No effect on apparent absorption of iron, manganese or copper although not statistically significant, absorption of zinc tended to decrease with increased phytic acid intake (44)... 

As reviewed recently by Solomons W, many dietary and non-dietary factors may affect the bloavallablllty of zinc. Dietary factors are subdivided Into "Intrinsic factors" and "extrinsic factors". "Intrinsic factors" relate to the chemical nature of zinc Itself. "Extrinsic factors" Include non-heme Iron, ethyl-enedlamlnetetraacetlc acid (EDTA), dietary fiber, phytic acid, calcium, copper and specific foods such as cow s milk, cheese, coffee, eggs, celery and lemon which have been demonstrated to decrease zinc bloavallablllty as well as other factors which may Increase zinc utilization. 

Phytates found in cereals, legumes, nuts and oil seeds form complexes with minerals, the mineral-phytate complexes in decreasing order of stability being zinc > copper > nickel > cobalt > manganese > calcium. Thus, zinc is affected most. An increase in pH results in phytic acid becoming more ionized and initiates binding to cations. 

The ability of zinc ions to block copper absorption, possibly by formation of- intestinal metallothionein that strongly binds copper, has led to its use in pharmacological doses in the management of Wilson s disease/ Similarly molybdate ion can form insoluble copper-molybdate complexes in the intestine that limit copper absorption. The detrimental effects of organic phosphate (phytic acid) in limiting zinc absorption are aggravated by excess dietary calcium, probably by formation of a highly insoluble Ca-Zn-phytate complex. The subject of these and other interactions has been reviewed, ... 

The production of hydroxyl radicals by tetra-chlorohydroquinone, a major metabolite of the widely used biocide pentachlorophenol in the presence of H2O2 was markedly inhibited by hydroxyl radical scavenging agents dimethyl sidphoxide and ethanol, as well as by tetrachlorohydroquinone radical scavengers desferrioxamine and other hy-droxamic acids (Zhu et al. 2000). In contrast, their production was not affected by the nonhydroxym-ate iron chelators, diethylenetriaminepentaacetic acid, bathophenanthroline disulphonic acid, and phytic acid, as well as the copper-specific chelator bathocuprione disulphonic acid. 

The recommended daily dietary doses of copper are 0.4-0.7 mg for children under 1 year, 0.7-2.0 mg for children aged 1 to 10 years, 1.5-2.5 mg for adolescents and 1.5-3.0 mg for adults. Resorption of copper and its retention in the body depend on the chemical form in which this element is present in the diet. Experiments on laboratory animals have shown a higher utilisation of copper in the form of neutral and anionic complexes contained in plant material than in the form of copper sulfate. Availability of copper increases the presence of proteins and amino acids in the diet. Also, carboxylic and hydroxycarboxylic acids stimulate resorption of copper. In contrast, higher doses of ascorbic acid, fructose, molybdenum, sulfur compounds and zinc significantly reduce the resorption of copper. Ascorbic acid reduces cupric compounds to slightly soluble cuprous compounds. The effect of phytic acid and dietary fibre on copper resorption is, in comparison with the effect of these components in zinc, less pronounced. 

ABSORPTION, METABOLISM, EXCRETION. Zinc is poorly absorbed less than 10% of dietary zinc is taken into the body, primarily in the duodenum. It appears that metallic zinc and zinc in its carbonate, sulfate, and oxide forms are all absorbed equally well. Large amounts of calcium, phytic acid, or copper inhibit zinc absorption. Cadmium appears to be a zinc antimetabolite. 

---