You have two thyroid hormones, triiodothyronine (T3) and thyroxine (T4). When there is a deficiency in these hormones, you have hypothyroidism. You need medical treatment for this condition. If ignored, it can lead to many adverse health conditions. But sometimes, dietary modifications may also help to a certain extent. If you have hypothyroidism, you need to avoid certain foods like soy, cabbage, broccoli, cauliflower and so on. At the same time, you need to increase your intake of iodine-rich foods. You can also increase your intake of iodine-enriched foods. But there has to be balance because too much iodine can also suppress thyroid gland activity. A high-fibre diet is also not good as it interferes with the absorption of thyroid medications. Another thing to keep in mind is that iron or calcium supplements can also adversely interact many thyroid medications. So, it is best to consult your doctor before changing or modifying your diet.