Absorption of iron from edible house crickets: a randomized crossover stable-isotope study in humans

Abstract

Background Edible insects are a novel source of animal protein. Moreover, edible insects contain iron concentrations similar to meat, potentially making them a valuable iron source for human consumers. Yet, it is unknown to what extent iron from insects is absorbed in humans. Objectives In this exploratory study, we assessed fractional iron absorption from house crickets (Acheta domesticus) consumed with refined (low-phytate, non-inhibiting) or non-refined (high-phytate, inhibiting) meals. Methods Intrinsically [57Fe]-labeled and control crickets were reared. Six iron-balanced experimental meals were randomly administered cross-over to 20 iron-depleted females (serum ferritin <25 µg/L; 18–30 years), in two time-blocks of three consecutive days, two weeks apart. Three meals consisted of refined maize flour porridge with either [57Fe]-labeled crickets, [58Fe]SO4 (reference meal), or unlabeled crickets plus [54Fe]SO4. The other three meals consisted of non-refined maize flour porridge with the same additions. Blood samples were drawn to assess the 14-day isotope enrichment in erythrocytes, and meal-specific fractional iron absorption was calculated. In vitro digestion was used to explore possible explanations for unexpected findings. Results Mean fractional iron absorption from 57Fe-labeled house crickets with refined maize porridge (3.06%) and from refined maize porridge with unlabeled crickets (4.92%) was lower than from the reference meal (14.2%), with respective mean differences of -11.1% (95% CI -12.6, -9.68%) and -9.29% (-10.8, -7.77%). Iron absorption from all meals based on unrefined maize porridge was low (<3%), and did not differ for the two meals with crickets compared to the reference meal. In vitro digestion showed that chitin, chitosan, and calcium limited iron bio-accessibility to a large extent. Conclusions Iron absorption from house crickets and fortified maize porridge with crickets is low, which may be explained by the presence of chitin and other inhibitors in the cricket biomass. This study was registered in the Netherlands Trial Register, https://www.trialregister.nl/trial/6821. This study was registered in the Netherlands Trial Register, Trial ID: NL6821, source ID: NL59400.081.16, https://www.trialregister.nl/trial/6821.

Should we provide edible insects in children's diets?

“…A comparable isotopic study was conducted to assess fractional iron absorption of maize porridge enriched with whole yellow mealworm powder or its dechitinized protein fraction in 21 females [18 ▪ ]. Contrary to findings of Mwangi et al [17 ▪ ], iron was moderately well absorbed with no differences between whole mealworms or its dechitinized protein fraction. The discrepancy in outcomes between these studies may be attributed to differences in iron and chitin abundance between the insect species, as well as in the structural properties of chitin during metamorphic stages of the insects, or differences in the presence of other antinutrient components.…”

“…Inclusion of the highest amount of cricket flour (7.5 g/100 g) led to higher levels of PUFA. A study by Ochieng et al [14 ] also found that adding grasshoppers to cookies increased the amounts of PUFAs. For nutritional value in children' diets, insects should be evaluated species by species for accurate determination of lipids.…”

“…Insects contain a notable amount of iron, however, the absorption of iron from edible insects has not been well established. Mwangi et al [17 ▪ ] carried out an exploratory isotopic study to establish fractional iron absorption from maize flour enriched with house crickets in 20 iron-depleted females. The fractional absorbed iron was low in all meals, specifically the cricket meals, probably due to inhibitory components such as chitin or other substances in the insects.…”

The role of meat in iron nutrition of vulnerable groups of the UK population

“…Iron occurs predominantly in nonhaem forms, bound to ferritin and transferrin and other transport and storage proteins (Mwangi et al, 2018). In a stable isotope absorption study undertaken in iron-depleted women, Mwangi et al (2022) found that iron absorption from intrinsically labelled house crickets (Acheta domesticus) added to maize porridge was low (~3%) which they suggested might be due to the presence of chitin and other inhibitors in the cricket biomass. A study of similar design examined iron absorption from mealworm larvae (Tenebrio molitor) and found it was similar to maize porridge (~5%); processing of the T. molitor biomass to reduce the chitin content did not increase iron bioavailability (Hilaj et al, 2022).…”

Novel insect-based child nutrition: the position of the nutritional committee of the Italian society of pediatric gastroenterology, hepatology and nutrition (SIGENP)

“…Furthermore, two recent RCT conducted in young females (18–45 years) reported conflicting results. While mealworm fortification [ 23 ] seems to provide a high non heme iron absorption, house rickets [ 24 ] showed a low iron absorption rate. No study to date has evaluated this specific topic in children.…”