This study aims to investigate a possible effect of iron status on temporary build-up of non-transferrin bound iron (NTBI) in healthy volunteers upon iron supplementation.

For Visit 1, blood samples will be collected to assess iron status. For Visit 2, after an overnight fast, iron supplement will be provided to participant before breakfast. Blood samples will be collected right before and 2 h after iron supplement consumption for NTBI analysis.

NTBI concentration before and after iron supplement consumption will be compared. Dependence of NTBI formation on markers of iron status (serum iron, transferrin, transferrin saturation, serum ferritin and hemoglobin) will be evaluated.

Inclusion Criteria:

• Apparently healthy volunteers (21 - 55 years old)
• C-reactive protein (CRP) < 5

Exclusion Criteria:

• Blood donation or significant blood loss (e.g. surgery) within the past 4 months
• Regular intake of iron and other nutrient supplements within the past 4 months
• Regular intake of medication except oral contraceptives
• Acute or recent inflammatory or infectious symptoms
• Chronic gastrointestinal disorders or metabolic diseases
• Pregnancy or lactation
• Coeliac disease or gluten-related disorders
• Iron overload conditions (serum ferritin concentration > 200 ng/mL for females, > 300 ng/mL for males)
• Non iron deficiency anemia [serum ferritin concentration within normal range (15-200 ng/mL for females, 30-300 ng/mL for males) but low hemoglobin (< 12 g/dL for females, < 14 g/dL for males)]