The effects of gastric juice acidity on bioaccessibility of some elements in selected foods

Abstract

The pH value of gastric juice changes between 1.5 and 3.5 in healthy people but the upper pH range can be as higher as 7 in the presence of a gastric ulcer or different gastric cancers. The effects of the acidity of gastric juice on the elemental bioaccessibility in different kinds of foods (peas, spinach, meat and fish) were determined by applying a physiologically-based extraction test over the relevant pH range, i.e. 1.5–7. The differences in the bioaccessibility of ten target elements (Al, As, B, Ba, Cd, Co, Cu, Fe, Mn and Pb) depending on the pH of gastric juice were investigated with analysis achieved using ICP-MS. The data obtained were subjected to Principal Component Analysis and Correlation Analyses. Higher extraction rates were observed at higher pH values for Al and B and at lower pH values for As, Ba, Cd, Co, Cu, Fe, Mn and Pb. For these latter analytes, the amount extracted can be less than half that at pH 7 compared with pH 1.5 or 2. The bioaccessibility of these latter elements is therefore much lower for patients suffering from gastric ulcers or gastric cancer. Although this lower bioaccessibility is advantageous for toxic analytes, e.g. Cd and Pb, it could potentially lead to deficiencies of the essential ones, e.g. Co, Cu, Fe and Mn.