Evidence for the role of dairy minerals and lactose in enhancing intestinal health

Lactose, magnesium and calcium, at the levels found in milk, were investigated to elucidate their influence on the functioning of the intestine. Two in-vitro models of the intestine incorporating Caco-2 cell monolayers were applied to examine the effect of these treatments on intestinal barrier function and nutrient transport. Intestinal barrier function was measured by change in epithelial electrical resistance. Transcellular uptake of calcium, magnesium and phosphorus of the intestinal cells at 100 minutes was determined by ICP-AES. The magnesium treatment increased monolayer resistance by 42 ohms at 1 minute, which was sustained for 100 minutes (±10 ohms). The magnesium treated cells had significantly higher calcium uptake, (+58%) compared to the glucose control. The calcium treated monolayer peaked in resistance at 40 ohms at 10 minutes declining thereafter. The glucose control peaked at 12 ohms at 1 minute then declined. The calcium treated cells had a transcellular mineral profile identical to the control. The lactose treated cells had sustained increase in resistance reaching 27 ohms at 100 minutes with a significantly higher phosphorus uptake, (+12%) compared to the glucose control. These results help elucidate the action of dairy components on the functioning intestinal cell and monolayer. Highlighted is the role of lactose whose rate-limited hydrolysis results in gradual release of saccharides to the intestine, causing minimal impact on permeability in contrast to the glucose control. This work further demonstrates Caco-2 cell models are useful tools that may be used to assist in the formulation of functional foods.