Bioavailability of Magnesium Diglycinate vs Magnesium Oxide in Patients with Ileal Resection

Abstract

Background: Patients who have undergone ileal resection are at risk for developing magnesium depletion/deficiency because of poor absorption and decreased intake as well as increased endogenous losses. Magnesium repletion is difficult to accomplish because of the cathartic action of most oral magnesium supplements at therapeutic doses. The results of in vitro and in situ studies show that magnesium diglycinate (chelate) represents a highly available form of magnesium that is absorbed in part as an intact dipeptide in the proximal small intestine. Methods: We conducted a double-blind, randomized crossover trial with 12 patients who had ileal resections in order to compare the bioavailability of a 100-mg dose of ²⁶Mg-labeled chelate with MgO in this patient population. Results: For the patient group as a whole, ²⁶Mg absorption was low but was not different for the two supplements (23.5% vs 22.8% for magnesium chelate and MgO, respectively). However, ²⁶Mg absorption was substantially greater from the chelate (23.5% vs 11.8%; p < .05) in the four patients who showed the greatest impairment of magnesium absorption with MgO and was better tolerated by all patients. Peak isotope enrichment also occurred significantly earlier after ²⁶Mg chelate than after ²⁶MgO ingestion (mean difference 3.2 ± 1.3 hours; p < .05), and the area under the enrichment vs time curve was greater after chelate ingestion (p < .05). Conclusions: Data from this study support the suggestion that some portion of magnesium diglycinate is absorbed intact, probably via a dipeptide transport pathway. Magnesium diglycinate may be a good alternative to commonly used magnesium supplements in patients with intestinal resection. (Journal of Parenteral and Enteral Nutrition 18:430-435, 1994)