Interaction of chemical species with biological regulation of the metabolism of essential trace elements

Abstract

Variations in the chemical speciation of dietary trace elements can result in the provision of different amounts of these micronutrients to the organism and might thus induce interactions with trace-element metabolism. The chemical species of Zn, Fe, Cu, and Mn can interact with other components of the diet even before reaching the site of absorption, e.g. by formation of poorly soluble complexes with phytic acid. This might considerably modify the amount of metabolically available trace elements; differences between absorptive capacity per se toward dietary species seems to be less important. Homeostasis usually limits the quantities of Zn, Fe, Cu, and Mn transported from the gut into the organism, and differences between dietary species are largely eliminated at this step. There is no homeostatic control of absorption of Se and I, and organisms seem to be passively exposed to influx of these micronutrients irrespective of dietary speciation. Inside the organism the trace elements are usually converted into a metabolically recognizable form, channeled into their biological functions, or submitted to homeostatically controlled excretion. Some dietary species can, however, be absorbed as intact compounds. As long as the respective quantities of trace elements are not released from their carriers, they are not recognized properly by trace element metabolism and might induce tissue accumulation, irrespective of homeostatic control.

Effects of increased iodine supply on the selenium status of kids

“…This leads to the organism being passively exposed to their supply in relation to their contents in the diet. The main homeostatic regulation of the selenium and iodine metabolisms in the organism takes place through their renal excretion (Windisch, 2002;Arova et al, 2003). In ruminants, however, this process can be to a certain extent under the influence of the changes during ruminal fermentation.…”

“…The regulation of intestinal element absorption concerns for instance Zn, Fe, Cu and Mn. On the other hand, the metabolic homeostasis of selenium and iodine is mostly maintained through the renal excretion of these elements and the regulation of their resorption in the intestine is minimal (Windisch, 2002).…”

Estudo da estabilidade do complexo ácido fítico e o íon Ni(II)

“…Diversas revisões relatam que minerais como o zinco, ferro, cobre e manganês formam complexos com baixa solubilidade com o ácido fítico [13], diminuindo a disponibilidade desses minerais no organismo [12,14,15]. A solubilidade do ácido fítico é apontada como dependente do pH e da proporção da taxa molar de minerais e do ácido [16].…”

“…O níquel é um micro elemento que atua como co-fator ou componente estrutural de metaloenzimas específicas em humanos, mas sua função metabólica e modo de ação no organismo são pouco conhecidos [25]. Em estudos experimentais com animais, o níquel se mostrou importante para o crescimento e reprodução, para o metabolismo de ferro e zinco e para a hematopoiese.…”

Comportamento do ácido fítico na presença de Fe(II) e Fe(III)

“…Diversos estudos (GRAF; EATON, 1990;PEARSON et al, 1998;BEBOT-BRIGUD et al, 1999;WINDISCH, 2002) têm mostrado a capacidade deste ligante em formar complexos na presença de íons metálicos no pH do intestino delgado alterando a disponibilidade metabólica desses elementos. O efeito combinado da fitase (EKHOLM et al, 2003) (RODRIGUES-FILHO et al, 2005).…”