Study On Zinc Absorption And Metabolism Of Zinc Amino Acid Chelate And Effecting Factors

Zinc amino acid chelate, which is main representative of the third generation of zinc, was studied earlier and extensively, and the nutritional function of zinc amino acid was confirmed by many researches. But the study on zinc absorption and metabolism were seldom. Three experiments were conducted to study the absorption, metabolism and effecting factors and relative biological availability of zinc amino acid chelate. In this study, rats were used as animal model, Zn-Lys and Zn-Met were studied as representative of zinc amino acid chelate. I Combined with radioactive isotope tracing, the technique of perfusing ligated intestinal segment, in vivo, in situ was utilized to study on zinc absorption of zinc amino acid chelate. Four trials were conducted in this part. Utilized the technique of perfusing ligated intestinal segment, in vivo, in situ and radioactive isotope tracing to determine Zn absorption of Zinc amino acid chelate (Zn-Lys and Zn-Met) by comparing with the compound of amino acid and ZnCl2 in the same moles of chelate. 24 fifty-day-old male Wistar rats fed purified diet (based on Isolated soy bean protein, corn starch and glucose), which ligated duodenum or jejunum were used in first trial to determined where is the more absorbed site of Zn. 18 fifty-day-old male Wistar rats fed two type diet (purified diet supplemented with 250 mg/kg Cu, purified diet supplemented with 1% phytic acid) were used in second trial to observe the effect factors of Zn absorption. 9 fifty-day-old male Wistar rats fed purified diet supplemented with 30mg/kg Zn, which Zn status is normal were used in third trial to survey the effect of Zn status on Zn absorption. 9 fifty-day-old male Wistar rats that ligated common bile duct were used in forth trial to determine the effect of endogenous secretion ligands on Zn absorption. The results indicated that: Under the condition of this study, compare with the jejunum, duodenum is the main site of zinc absorption. Lysine and Methionine could increase the absorption of zinc. Compared with the compound of amino acid and ZnCI2 in the same moles of chelate, rats could effectively absorb zinc in Zn-Lys and Zn-Met. 250mg/kg Cu or 1% phytate in diet could significantly decrease zinc absorption in ZnCl2 and zinc amino acid chelate, however, influence on the latter was smaller than that on the former. Zinc content in liver, spleen and muscle and alkaline phosphatase of serum of rats fed purified diet supplemented with 250 mg/kg Cu or 1% phytate for 21 days was significantly lower than that of rats fed purified diet. Zinc absorption of rats with normal zinc status is lower that that of zinc deficiency rats. Zinc status of rats fed purified diet supplemented with 30mg/kg zinc for 21 days was better than that of rats fed purified diet (zinc content 2mg/kg). Absorption of zinc in three zinc sources was decreased after ligated common bile duct but decrease degree of zinc absorption in ZnCI2 was largest. According to the results of comparing with the compound of amino acid and ZnCI2, absorption of zinc in zinc amino acid in ligated duodenum was greatest and the ability of resisting factors that disturb zinc absorption was so strong and hardly affected of endogenous secretion ligands, zinc amino acid chelate was an excellent zinc additive. The results showed that the technique of perfusing ligated intestinal segment in situ combining with radioactive isotope tracing was an ideal method to study trace element absorption. 2 The technique of directly perfusing stomach combined with radioactive isotope tr...