Soil saprophages as an emerging global source of micronutrients

‘Hidden hunger’ occurs in humans and livestock and stems from deficiencies in microelements, essential amino acids, and vitamins. Triggered by insufficient intake of micronutrients in food and feed, even when macronutrients are abundant, hidden hunger can result in the development of serious diseases and pathological conditions. Finding sufficient micronutrients is often challenging because they are either obtained from limited external natural sources or synthesised de novo. Soil-dwelling saprophages comprise one of the largest proportions of zoomasses on Earth but remain surprisingly overlooked as a potential micronutrient source. To assess their nutritional content concerning micronutrients, we selected 31 invertebrate species obtained from natural ecosystems of European Russia or widely cultivated species originating mainly from tropical regions. They belong to major soil saprophage taxa: cockroaches (Blattodea), beetle (Coleoptera) larvae and imagoes, springtails (Collembola), millipedes (Diplopoda), fly (Diptera) larvae, earthworms (Haplotaxida), woodlice (Isopoda), crickets (Orthoptera). We assessed their proteinogenic amino acid, microelement, and vitamin composition. Taxonomic differences in the composition and ratio of micronutrients were determined and we identified specific taxa naturally enriched with micronutrients for future consideration as potential candidates for incorporation into food and feed supplements to alleviate hidden hunger in livestock and humans.