Comparative Analysis of Iodine Levels, Biochemical Responses, and Thyroid Gene Expression in Rats Fed Diets with Kale...

Iodine is a key micronutrient essential for the synthesis of thyroid hormone, which regulates metabolic processes and maintains overall health. Despite its importance, iodine deficiency is a global health issue, leading to disorders such as goiter, hypothyroidism, and developmental abnormalities. Biofortification of crops with iodine is a promising strategy to enhance the dietary iodine intake, providing an alternative to iodized salt. Curly kale (Brassica oleracea var. sabellica) is a nutrient-rich vegetable high in vitamins A, C, K; minerals; fiber; and bioactive compounds with antioxidant, anti-inflammatory, and detoxifying properties. This study evaluates the effects of diets containing iodine-biofortified curly kale ('Oldenbor F₁' and 'Redbor F₁') on iodine content, tissue iodine levels, and various biochemical parameters in laboratory rats. The biofortified curly kale was enriched with 5,7-diiodo-8-quinolinol. The iodine content in the AIN-93G (control) diet and the non-biofortified curly kale diets did not differ significantly. However, diets with 5,7-diiodo-8-quinolinol biofortified kale showed significantly higher iodine levels compared with the control diets. Tissue analysis revealed the highest iodine concentrations in the liver and kidneys of rats fed diets with biofortified curly kale, indicating better iodine bioavailability. Biochemical analysis showed that rats fed the biofortified kale diet had lower total cholesterol (TC) and triglyceride (TG) levels compared with rats fed the control diet. Additionally, the biofortified diet improved the liver function markers (ALAT, ASAT) and reduced oxidative stress markers (TBARS). The study also investigated the expression of thyroid-related genes (Slc5A5, Tpo, Dio1, Dio2) in response to diets containing biofortified kale. The results demonstrated significant changes in gene expression, indicating adaptive mechanisms to dietary iodine levels and the presence of bioactive compounds in the biofortified kale. The study also observed variations in uric acid levels, with lower concentrations in rats fed a diet with biofortified curly kale. Biofortified curly kale supports thyroid function and improves liver and kidney health by reducing oxidative stress and modulating key biochemical and genetic markers. These findings suggest that biofortified curly kale can effectively increase dietary iodine intake as a nutritional intervention to address iodine deficiency and promote overall health.