Due to the growing world population, there is a need to develop viable ecological and nutritional alternatives to animal food products. However, animal products are a key dietary source of well-absorbed iron, and iron deficiency and iron deficiency anemia remain highly prevalent in high- and low-income countries. Meat and fish provide a substantial proportion of absorbed iron in the western diet by two distinct components: a) heme iron is well absorbed (20-45% fractional absorption) and is not affected by most dietary enhancers and inhibitors, which often affect non-heme iron absorption; b) peptides in muscle meat exert an enhancing effect the absorption of non-heme iron contained in other meal components. The potential of edible insects as a dietary source of well-absorbed iron has not been investigated in detail. In particular, it is unclear whether insects provide an iron moiety similar to hemoglobin which would be well absorbed and unaffected by other dietary components, and whether their presence in a test meal exerts an enhancing effect on iron bioavailability from the whole meal.

Furthermore, chitin, a major component of insect biomass, is a known iron binder and is potentially responsible for a decreased iron absorption from insect-based foods. Decreasing chitin content could allow the high amounts of iron in insects to be well-absorbed, and enhance the absorption of iron from plant-based foods. To differentiate iron absorption from insect biomass from other sources, insects will be intrinsically labelled with the stable iron isotope 57Fe, while other food iron components will be labelled with the iron isotope 58Fe.The present study will provide novel data to elucidate the nutritional value as sources of dietary iron of insect species (Tenebrio molitor). Since 2017 T.molitor is recognised as an edible insect in the Swiss food legislation and commercially available (Essento Food AG, Zürich; Insekterei, GmbH, Zürich).

Inclusion Criteria:

• Female, 18 to 45 years old
• Normal Body Mass Index (18.5 - 25 kg/m2)
• Body weight ≤ 65 kg
• Non-anemic (hemoglobin (Hb) >12.0 g/dL)
• Low iron status (being in the lower half of the serum ferritin distribution at screening)
• Normal CRP (<5.0 mg/L), indicating no inflammation
• Knowledge of English at least at level B2 (assessed by self-declaration)
• Signed informed consent

Exclusion Criteria:

• Pregnancy (assessed by self-declaration)
• Lactating up to 6 weeks before study initiation
• Any metabolic, gastrointestinal kidney or chronic disease such as diabetes, hepatitis, hypertension, cancer or cardiovascular diseases (according to the participants own statement)
• Continuous/long-term use of medication (except for oral contraceptives and anti-acne medication)
• Consumption of mineral and vitamin supplements within 2 weeks prior to 1st meal administration
• Blood transfusion, blood donation or significant blood loss (accident, surgery) over the past 4 months
• Earlier participation in a study using iron stable isotopes or participation in any clinical study within the last 30 days
• Participant who cannot be expected to comply with study protocol e.g. not available on certain study appointments
• Cigarette smoking ( > 1 cigarette per day)