Now there are two hypotheses about the absorption mechanism of organic trace elements (Ashmead, 1993): the complete absorption hypothesis and the competitive absorption hypothesis. The biological activity of organic trace elements is greater than in organic trace element.
Perhaps organic trace elements can a void interference by anti-nutritional factors and are absorbed completely in digestive tract and (or) the metabolic pathways and mechanism of action of organic trace elements, which are absorbed differently from in organic trace elements in histocyte (Spears, 1989; Carlson etal.,1997). Other investigators report in directly that the absorption pathways of organic trace elements may be different from in organic forms. To date, no direct experimental evidence proves which hypothesis better explains the absorption of organic trace elements in intestine.