Dietary Adaptation of Non-Heme Iron Absorption in Vegans: A Controlled Trial

Non-heme iron, mainly from plant foods, is theoretically less bioavailable than heme iron from animal food, which might increase the risk of iron deficiency in vegans. This study aimed to evaluate acute changes in plasma iron levels following non-heme iron intake in vegans compared with omnivores and to explore the mechanisms regulating these changes. Twenty-seven participants (18-30 years old) were divided into vegans and omnivores. After baseline measurements (body composition, blood pressure, and blood biomarkers), the participants consumed 150 g of pistachios. Blood samples were taken at baseline, 120 and 150 min after consumption to measure serum iron. The main outcome was the area under the curve (AUC) of serum iron The AUC for serum iron was significantly higher in vegans (1002.8 ± 143.9 µmol/L/h) compared to omnivores (853 ± 268.2 µmol/L/h) (p = 0.04; ES: 0.68). Multivariate regression analysis identified significant associations with hepcidin levels (β = -0.5, p = 0.03) and basal iron levels in the vegan group. This study demonstrates higher non-heme iron absorption in vegans compared to omnivores, highlighting the physiological adaptations involved in iron metabolism in plant-based diets. Larger longitudinal studies are needed to confirm these findings and assess plant-based diets' long-term effects on iron metabolism.