Iron Supplementation Limits Cadmium Accumulation and Mitigates its Toxicity in Lettuce: A Food Safety Perspective

Journal Article

2026

Published in: https://doi.org/10.1007/s42729-026-03399-y

Leafy green vegetables highly accumulate cadmium (Cd) in edible tissues, representing a significant health risk for consumers. Despite growing interest in Cd phytotoxicity, studies specifically addressing the interplay between Fe nutrition and Cd stress in lettuce, particularly regarding photosystem integrity and subcellular Cd compartmentalization, remain limited. This study evaluates the effectiveness of iron supplementation to reduce Cd accumulation in lettuce (Lactuca sativa L.), based on the hypothesis of antagonistic interactions between Cd and Fe. Lettuce plants were hydroponically cultivated using 10, 50, or 250 µM Fe, with or without cadmium (15 µM CdCl2). Plant growth, photosynthetic performance, and cadmium accumulation were assessed. An integrated biophysical approach was applied to evaluate photosystem I and II functional integrity, and subcellular Cd distribution among soluble, cell wall, and organelle fractions was determined to provide mechanistic insights into Fe-mediated Cd tolerance. Cd exposure induced leaf chlorosis and strongly inhibited plant growth, reducing shoot and whole-plant dry weight by 42% and 37%, respectively (p < 0.05), along with marked decreases in plant size and leaf surface area. Cadmium also severely impaired leaf gas exchanges and the functional integrity of photosystems I and II. These detrimental effects were substantially alleviated by iron supplementation, especially at 50 and 250 µM doses, which increased shoot dry weight by 26% and 33%, respectively, compared with Cd-stressed plants supplied with 10 µM Fe (p < 0.05). Shoot Cd concentration exceeded 100 µg g−1 DW, reaching 484 µg Cd g−1 DW under Cd exposure, indicating a high Cd accumulation capacity of lettuce under the present hydroponic conditions. However, high Fe supply significantly reduced Cd concentrations by 40% in roots and 51% in shoots compared with Cd-stressed plants supplied with low Fe (p < 0.05). In addition, Fe supply altered the relative intra-leaf distribution of Cd, increasing the proportion of Cd associated with the operationally defined soluble fraction, which accounted for 69% of total shoot Cd under high Fe supply. Overall, these findings provide mechanistic evidence that increasing Fe availability, within an optimized and non-toxic range, may alleviate Cd-induced phytotoxicity and reduce Cd accumulation in edible lettuce tissues by limiting Cd transfer through modulation of subcellular compartmentalization, with important implications for food safety.