1. Soy and its derived products. Soy contains isoflavones, which can interfere with the body’s capacity to absorb iodine and create thyroid hormones. This is especially concerning for people with iodine shortage or who use thyroid hormone replacement. Tip: If you are using levothyroxine, avoid consuming soy products within 3-4 hours of taking your medicine. Examples include soy milk, tofu, tempeh, edamame, and miso.

2. Raw Cruciferous vegetables. While greens such as kale and broccoli are healthful, eating them raw in high quantities can reduce thyroid hormone production. They include goitrogens, substances that may limit iodine absorption, which is necessary for proper thyroid function. Tip: Cooking cruciferous veggies lessens their goiterogenic properties. Steaming or sautéing is suggested. Examples include raw cabbage, broccoli, kale, and Brussels sprouts.

3. Gluten. Gluten can cause inflammation and immune system flare-ups in those who have autoimmune thyroid illnesses such as Hashimoto’s disease. It may also harm the gastrointestinal lining, reducing nutritional absorption and medicine efficacy. Tip: If you have recurrent lethargy, digestive troubles, or have been diagnosed with Hashimoto’s, try a gluten-free diet. Examples include wheat, barley, rye, and processed oats.

4. Refined sugar. Excess sugar promotes inflammation, raises insulin resistance, and can exacerbate hypothyroidism symptoms such as weight gain, mood swings, and brain fog. Tip: Replace refined sugar with natural sweeteners such as honey (in moderation) or low-glycemic fruits. Examples include candy, pastries, sweet drinks, and prepackaged desserts.

5. Processed, high-sodium foods. People with underactive thyroids are more likely to experience excessive blood pressure and water retention. Processed foods are generally high in sodium, which can exacerbate these disorders and strain the cardiovascular system. Tip: Read food labels carefully and select “low sodium” options wherever available. Examples include instant noodles, canned soups, deli meats, and frozen dinners.

6. Coffee (used too soon after medication) Drinking coffee too soon after taking thyroid medicine might decrease absorption by up to 60%, reducing its effectiveness and slowing recovery. Tip: Wait 30 to 60 minutes after taking levothyroxine before drinking your daily coffee.