The effect of dechitinization on iron absorption from mealworm larvae (Tenebrio molitor) flour added to maize meals: stable-isotope studies in young females with low iron stores

Abstract

Edible insects have a low ecological footprint and could serve as an alternative dietary iron source. However, chitin, a major component of insects, avidly binds iron and might inhibit iron absorption. We aimed to measure fractional iron absorption (FIA) from Tenebrio molitor-based test meals with and without dechitinization, and to assess the effect of native and low chitin T. molitor on FIA from iron-fortified maize porridge. We measured iron absorption in young females with low iron stores (n=21) from 1) labeled (54FeSO4) fortified maize porridge (maize alone); 2) intrinsically labeled (57Fe added during rearing) T. molitor larvae with native chitin content (NC) added to maize alone; and 3) dechitinized intrinsically labeled (57Fe) T. molitor larvae with low chitin content (LC) added to maize alone. We determined FIA using erythrocyte isotope incorporation and measured in vitro iron dialyzability from the 3 meals. NC and LC T. molitor had similar mean±SD iron content (12.0±0.1mg/100g). Geometric mean (95% CI) FIAs from the 3 test meals were 1) maize alone: 5.8% (3.2%, 10.8%); 2) maize+NC T. molitor: 5.3% (2.5%, 11.3%) and 4.1% (1.9%, 8.7%); and 3) maize+LC T. molitor: 4.6% (2.0%, 10.3%) and 4.0% (1.8%, 9.2%), for extrinsic and intrinsic labels, respectively. FIA from NC and LC T. molitor did not significantly differ, and both were lower (P<0.005) than FIA from the labeled maize porridge in the 3 meals, which did not significantly differ. The slopes of the relations between FIA and serum ferritin in the different meals and from the intrinsic and extrinsic labels did not significantly differ. T. molitor biomass does not strongly affect iron absorption when added to maize porridge. Our data suggest T. molitor iron is absorbed from the common nonheme iron pool. Native T. molitor is high in iron which is moderately well absorbed, suggesting it could be a valuable dietary iron source.This trial was registered at clinicaltrials.gov as NCT04510831.