Comparison of the Bioaccessibility of Two Formulations of Magnesium Bisglycinate Using an In Vitro Simulation of the Upper Gastrointestinal Tract.

Modern diets are often deficient in magnesium, making magnesium supplementation an important consideration for overall human health. However, the efficiency of magnesium release and absorption in the small intestine varies among different magnesium formulations. The objective of this study was therefore to assess whether using the same magnesium salt type in different formulations could affect efficiency of magnesium release and passive diffusion in the simulated human intestine. This study utilized an in vitro simulation of the upper gastrointestinal tract under fasted conditions to evaluate capsule dissolution and levels of bioaccessible and dialyzable magnesium during transit for two magnesium bisglycinate supplements containing a similar magnesium content (Chelamax® and Albion®). For this purpose, the validated Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) technology platform was used and magnesium fractions were determined by inductively coupled plasma optical emission spectroscopy following sample extraction. Analytical validation proved that the model was fit for purpose (94-102% recovery, RSD ≤ 2.4%, R2 > 0.999, LOQ 0.04 mg/kg). Visual capsule scoring found that the Chelamax® product dissolved later in gastrointestinal transit than the Albion® product. Magnesium bioaccessibility was higher for the Chelamax® versus Albion® product in early phases of the gastrointestinal tract (i.e. duodenum), resulting in 17% higher overall Mg availability after the small intestinal incubation was complete. The level of dialyzable magnesium at the end of the small intestinal incubation was significantly higher with the Chelamax® versus Albion® product (53 mg vs. 39 mg; p = 0.0009). These results demonstrate that the Chelamax® product showed significantly higher in vitro efficiency of potentially absorbable magnesium, even upon using the same magnesium salt type, suggesting the crucial role of product formulation. Even though a proven valid in vitro methodology for the prediction of effectiveness of magnesium availability was used, future in vivo studies should confirm these findings.