用体外消化／Caco-2细胞模型观察维生素C和柠檬酸对铁生物利用的影响

Effects of ascorbic acid and citric acid on iron bioavailability in an in vitro digestion/ Caco-2 cell culture model

目的采用体外消化/Caco-2细胞模型来观察维生素C和柠檬酸对铁生物利用的影响,并验证在本实验室建立的体外消化/Caco-2细胞模型的有效性。方法利用一个带透析膜的插入环将体外消化和Caco-2细胞培养结合在一起,模拟体内环境,使食物的消化和吸收在该模型中能同时进行。并在含铁样品液中分别加入维生素C和柠檬酸,以Caco-2细胞的铁蛋白形成量作为反映铁生物利用率的指标。结果在样品液铁浓度<100μmol/L时,细胞中铁蛋白形成量随着铁浓度的增加而递增;加维生素C组的细胞铁蛋白形成量高于加柠檬酸组;加入维生素C使方法更灵敏,加入柠檬酸使测定的铁浓度范围更宽。结论在本实验室建立的体外消化/Caco-2细胞模型是成功的,维生素C对铁生物利用的促进作用高于柠檬酸。

Objective To study the effects of ascorbic acid and citric acid on iron bioavailability using an in vitro digestion/Caco-2 cell culture model and evaluate the validity of this cell model. Methods This model combined in vitro digestion technique with Fe uptake by Caco-2 cells by utilizing an inserted ring attached to a dialysis membrane to simulate the gastrointestinal environment to allow simultaneous food digestion and uptake processes. Ferritin formation in the Caco-2 cells was measured as the indicator of Fe uptake by exposing Caco-2 cells to the digests containing Fe plus ascorbic acid or citric acid. Results When Fe concentration in the digest was below 100 μmol/L, ferritin formation increased with the Fe concentration in the digest. The iron digest containing ascorbic acid exhibited a significant increase in ferritin formation relative to the iron digest containing citric acid. The model was more sensitive to lower iron concentrations when ascorbic acid was present in the digest, while wider range of iron concentration could be assessed by addition of citric acid. Conclusions The in vitro digestion/Caco-2 cell culture model is a valuable tool for iron bioavailability assessment. Ascorbic acid has a stronger effect than citric acid in promoting iron bioavailability.