Potato tubers biofortified with iodoquinolines after heat treatment – Analysis of quality parameters, bioavailability of iodine and selected thyroid-regulated biochemical parameters in the Wistar rats

Iodine is essential for thyroid function and metabolism. We biofortified potato tubers (Solanum tuberosum L.) with two organic iodoquinolines-8-hydroxy-7-iodo-5-quinolinosulphonic acid (8-OH-7-I-5QSA) and 5-chloro-7-iodo-8-quinoline (5-Cl-7-I-8-Q)-and evaluated how steaming, baking and boiling affect iodine retention, tuber composition and antioxidant activity, and how steamed, biofortified potatoes influence iodine bioavailability and selected thyroid-regulated biochemical parameters in Wistar rats. Baking in foil caused the smallest iodine losses, while boiling led to the greatest; among the organic forms, 5-Cl-7-I-8-Q showed higher heat stability than 8-OH-7-I-5QSA.In vivo, despite equivalent iodine intake across groups, rats fed diets with steamed biofortified potatoes exhibited metabolic effects beyond iodine supply: triglycerides decreased (BP1, BP2), HDL increased (BP1), glutathione reductase decreased (BP2), and TSH rose without T3/T4 changes (BP2). Iodine in urine, faeces and tissues showed no material between-group differences, indicating that compound-specific actions or metabolites, rather than iodine per se, likely drive these outcomes. These findings support iodine biofortification as a feasible dietary strategy while highlighting the need to assess long-term safety and to identify circulating parent compounds/metabolites.