Influence of Diet on the Bioaccessibility of Zn from Dietary Supplements: Findings from an In Vitro Digestion Model and Analytical Determinations.

Abstract

Zn is an essential mineral nutrient for human health. Its deficiency may result not only from insufficient intake but also from impaired absorption. Dietary components released from the food matrix during digestion can interact in ways that either enhance or inhibit mineral bioavailability. The primary aim of this study was to evaluate the bioaccessibility of Zn from dietary supplements, particularly in the context of diet type, chemical form, and pharmaceutical formulation effects. The experiment was conducted using an in vitro gastrointestinal digestion model with cellulose dialysis membranes. Zn content after digestion was determined using flame atomic absorption spectrometry (F-AAS). The method employed had been previously developed and validated for use in determining the bioaccessibility of mineral nutrients. The bioaccessibility of Zn from the standard, basic, and high-fiber diets was 19.43, 16.18, and 8.12%, respectively. In the presence of a standard diet, the bioaccessibility of Zn from dietary supplements was within the range 1.77-36.09%, in the presence of a basic diet, 1.05-35.86%; and in the presence of a high-fiber diet, 1.37-35.94%. The highest values were observed for zinc picolinate, whereas the lowest were determined for zinc oxide. A high-fiber diet significantly reduced Zn bioaccessibility. Bioaccessibility is also strongly dependent on the chemical form of zinc.