Influence of salt form and concentration on the absorption of magnesium in rat small intestine.

The influence of magnesium concentration and salt form on the absorption of this element in the rat small intestine was investigated. The following magnesium salts were studied: gluconate, fumarate, and chloride. At 1 and 5 mM concentrations absorption was most efficient from gluconate whereas at 10 mM absorption from fumrate was more efficient. Mg2+ absorption half-life (t50%) varied with salt and concentration. The Mg2+ absorption half-life for magnesium gluconate at 10 mM concentration was 42 times as long as at 1 mM concentration. The biggest area under the curve, which characterizes substance bioavailability, was observed for each of the investigated salts at 5 mM. Therefore, we may conclude that magnesium administration at 5 mM concentration would be optimal.