The effect of oestrogen and dietary phyto-oestrogens on transepithelial calcium transport in human intestinallike Caco-2 cells

Recently, dietary phyto-oestrogens (PO) have been suggested as possible alternatives to oestrogen therapy (hormone replacement therapy) as a means of preventing bone loss associated with ovarian hormone deficiency. While PO, which exhibit oestrogen-like activity, act directly on bone cells, their protective effect on bone may be partly due to their ability to enhance Ca absorption. Therefore, the aim of the present study was to investigate the effect of 17(beta)-oestradiol, 1 nM1,25-dihydroxycholecalciferol, or 50 (beta)-oestradiol had no effect on Ca absorption. Unexpectedly, both PO decreased Ca absorption (by about 17–19 % compared with control, P<0·05), by reducing transcellular Ca transport in Caco-2 cells grown in oestrogen-replete media. This inhibitory effect disappeared when monolayers were grown in oestrogen-deplete media. In conclusion, PO at high luminal concentrations either had no effect or reduced Ca absorption in Caco-2 cells, dependent on oestrogen status. The effect of lower concentrations of these compounds needs to be investigated.