Bioaccessibility and bioavailability assessment of microalgae-derived minerals for human nutrition

Microalgae-derived minerals are emerging as sustainable nutrient sources for humans; however, knowledge of their bioaccessibility and bioavailability remains limited. This study systematically evaluated mineral (Fe, Ca, Zn, Mg, Cu, Mn, P, K), carbon (C), and nitrogen (N) content and their bioaccessibility from 9 microalgae samples using standardized INFOGEST 2.0 in vitro digestion, combined with a human intestinal epithelial (Caco-2) cell model for iron bioavailability assessment. Total mineral content varied notably (Fe, 72.1 - 3120.9 mg/kg; Ca, 517.9 - 24146.3 mg/kg; Zn, 12.1 - 282.1 mg/kg; Mg, 379.2 - 15245.9 mg/kg). Mineral bioaccessibility exhibited wide variability; for instance, Fe bioaccessibility ranged from 0.5% in Tetraselmis chuii to 83.4% in green Chlorella vulgaris. The bioaccessibility of Ca (0- 82.3%), Zn (51.9 - 62.2%), Cu (7.5 - 89.8%), Mg (68.0 - 92.2%), Mn (6.75 - 84.3%), P (9.7 - 100%), and K (91.1 - 100%) also showed large interspecies differences, similar for C (12.4 - 78.1%) and N (63.1 - 93.8%). The iron bioavailability of Arthrospira platensis and unlysed Haematococcus pluvialis is the highest, comparable to that of FeSO4. Tetraselmis chuii and Dunaliella salina exhibit relatively lower bioavailability; however, their levels remain higher than those found in conventional foods. This study demonstrates the potential of microalgae as an innovative and sustainable food source, offering highly bioaccessible minerals and bioavailable iron for human nutrition. It emphasizes the necessity of evaluating both bioaccessibility and bioavailability to accurately assess the nutritional value of microalgae-derived minerals, thereby informing future dietary applications and nutritional strategies in food science.