Hashimoto's thyroiditis (HT) is the most common cause of chronic hypothyroidism in areas with sufficient iodine, stemming from an autoimmune response against thyroid peroxidase and/or thyroglobulin. It is the most prevalent autoimmune thyroid disease and a leading cause of overall hypothyroidism. Even when they reach euthyroidism, 82% of treated women with HT still have excess body weight, and 35% of them are obese. Thyroid dysfunction can affect the function of adipose tissue and lead to metabolic disturbances. Leptin can stimulate thyroid-stimulating hormone secretion, while thyroid-stimulating hormone can influence leptin release from adipose tissue. Additionally, HT patients often exhibit high levels of C-reactive protein and interleukin-6, suggesting an association between increased thyroid-stimulating hormone levels and the inflammatory process, which may contribute to comorbid disease risk in individuals with HT. Nutrition can serve as a complementary treatment for HT by affecting thyroid functions and having anti-inflammatory properties. Dietary interventions may involve eliminating gluten, lactose, or certain food components, or focusing on an anti-inflammatory dietary pattern while preventing nutritional deficiencies. Therefore, this study is a randomized controlled, single-blind trial designed to evaluate the effects of a gluten-free, lactose-free diet and a diet enriched with Aronia Melanocarpa, both individually and in combination, as well as healthy dietary protocols, on autoantibody levels, leptin, ghrelin, oxidative response, and weight loss in patients with Hashimoto's thyroiditis. The study aims to recruit a minimum of 80 participants aged 18-65 years, diagnosed with Hashimoto's thyroiditis at Istanbul Medical Faculty Hospital. In the initial face-to-face interview, participants will provide sociodemographic information, dietary habits, anthropometric measurements, and dietary intake records through a questionnaire. The study involves the inclusion of Aronia Melanocarpa in the diet (high anthocyanin content, 69.24 mg/100 ml), a gluten-free and lactose-free diet, both interventions being applied together, and the application of only healthy nutrition protocols to patients over an 8-week period, with serum assessments of thyroid-stimulating hormon, free T4, free T3, anti-thyroid peroxidase, anti-Tg, interleukin-6,anti tumor necrosis factor alpha, C-reactive protein and leptin-ghrelin levels at the beginning and end of the study. The goal is to create recommendations for patients, improve their quality of life, and establish sustainable nutritional interventions.

Inclusion Criteria:

• Being diagnosed with Hashimoto's thyroiditis by a doctor,
• Being a female individual between the ages of 18-65,
• Not being diagnosed with any chronic disease that would negatively affect functioning other than Hashimoto's thyroid,
• Not having used selenium and iodine supplements in the last month,
• Individuals should not lose more than 4 kg of weight in the last month,
• Not having been on a strict elimination diet for more than 4 months in the last year,
• Not having applied any nutritional intervention during the last three months before the study.

Exclusion Criteria:

• Pregnant or breastfeeding mother,
• Individuals with chronic diseases,
• Individuals allergic to red fruits

Since the prevalence of the disease is high in female individuals, it will be conducted with female individuals.