Impact of iron-enriched diets on the nutritional composition and microbiome diversity of house crickets (Acheta domesticus)

Iron deficiency (ID) and iron-deficiency anaemia (IDA) pose significant global health challenges. ID and IDA are particularly widespread in Sub-Saharan Africa and South Asian countries, where reliance on plant-based foods is high. Edible insects provide an alternative nutritious food source, rich in both protein and essential minerals and trace elements. Little is known about how dietary iron manipulation affects the trace element bioaccumulation and microbiome community composition of edible insects. This study examined the impact of dietary iron supplementation on the growth, survival, nutrient profile, and microbiome of Acheta domesticus. Experimental diets were formulated using iron (II) sulphate heptahydrate, resulting in final iron concentrations ranging from 333.45 mg Fe/kg (control diet) to 6923.39 mg Fe/kg (100 mM Fe diet). Iron supplementation significantly altered the cricket trace element profile, with iron levels increasing fivefold from basal 21.38 mg/kg to 118.34 mg/kg in the highest iron treatment group. Concurrently, manganese levels showed a strong negative correlation with dietary iron, while zinc and cadmium displayed non-significant downward trends. High-iron diets statistically altered dry matter, chitin, and TBARS, whereas carbohydrates, protein, glycogen, and lipids remained stable. Amino acid profiles shifted progressively, with branched-chain, sulphur-containing, and aromatic amino acids peaking in the 25 mM Fe group. In contrast, the diversity and overall structure of the microbial community remained unaffected across all treatments. In conclusion, tailoring dietary iron can significantly boost the iron content of Acheta domesticus without compromising host survival or altering core microbial structures. To optimize insect rearing strategies aimed at alleviating human micronutrient deficiencies, a feeding dose of 10-25 mmol Fe/kg is recommended.