Oral bioaccessibility of metal(oid)s in commercial zeolite used as a dietary supplement: implications to human health risk

In Mexico and worldwide, zeolite minerals are becoming popular as a nutritional supplement for human health and exercise performance. The objective of this research is to characterize eleven (11) commercial products advertised as clinoptilolite for human consumption. To achieve this, we measured eight metal(loid) by portable X-ray fluorescence; each product's mineralogy and oral bioaccessibility were obtained by X-ray diffraction and in vitro tests, respectively. The most abundant toxic metals were As (118.7 mg.kg(-1)), followed by Pb (58.8 mg.kg(-1)), and V (39 mg.kg(-1)). Fe (1.1%) was the most abundant essential element followed by Mn (689.4 mg.kg(-1)) > Zn (68.3 mg.kg(-1)) > Cr (64.8 mg.kg(-1)), and Cu (16.4 mg.kg(-1)). Mineral identification showed that four samples did not contain clinoptilolite but quartz, calcite, and gypsum. In vitro test for oral bioaccessibility (gastric and intestinal) return the highest percent value of Mn (30.6 %) followed by As (15.8 %) > Cu (14.1 %) > V (5.2 %) > Cr (4.8 %) > Fe (3.9 %), and Pb (3.4 %). After product ingestion, we also conducted a risk assessment, including non-carcinogenic hazard index (HI) and carcinogenic risk (CR) calculation. Five of the studied samples had H I > 1 and CR between 10 and 8 and 10-4, posing potential non-carcinogenic and cancer risks to consumers.