There are no specific foods or dietary supplements that are helpful in treating thyroid disorders. Instead, patients who have hyperthyroidism should avoid taking too much food containing iodine, such as seafood and seaweed. As the mineral iodine plays a key role in making thyroid hormones, too much iodine can make hyperthyroidism worse by leading the thyroid gland to produce too much thyroid hormone. Until their condition is controlled, patients with hyperthyroidism should also avoid drinking excessive caffeinated beverages or doing vigorous exercise, as these may worsen the symptoms of palpitations and a fast heart rate.
Since iodine is essential for making thyroid hormone, iodine deficiency can cause hypothyroidism. However, iodine deficiency is uncommon in most developed countries due to iodine additives in salt and food. Eating a balanced diet makes taking supplemental iodine generally unnecessary. On the contrary, too much iodine can cause hyperthyroidism in some people, a condition known as iodine-induced thyrotoxicosis, or worsen pre-existing hyperthyroidism. Brassicas such as broccoli, Brussels sprouts, cabbage, cauliflower, and kale, may contribute to swelling of the thyroid gland (goiter) in some cases, but consumption would need to be very high before this is a real concern. This is not a problem under normal dietary conditions and the potential risk is extremely low.
If you have hypothyroidism and are taking thyroxine replacement, it is important to avoid certain foods and supplements that may interfere with thyroxine absorption. These include antacids, calcium, iron supplements, and food rich in calcium such as milk, soy and tofu. A gap of 4 hours between thyroxine and these potential interfering substances would be adequate to ensure there is no significant impact on blood thyroxine levels.
Oral supplements containing Biotin, a water-soluble vitamin that boosts hair and nail health, can interfere with the measurement of thyroid hormones. Biotin does not affect thyroid hormone levels, but these supplements should be stopped for a week before measuring your thyroid function so that your thyroid status is accurately reflected.
Strenuous exercise in patients with uncontrolled hyperthyroidism or hypothyroidism is not advisable since these conditions affect the person’s metabolism and heart rate (increase in hyperthyroidism or decrease in hypothyroidism). With proper treatment of the thyroid disorder and monitoring, a return to exercise is safe and can improve the remaining symptoms. Patients with hypothyroidism may experience fatigue and weight gain that do not always resolve completely with the use of thyroid medications. Regular exercise can help to boost energy levels and maintain a healthy weight. It is important to talk to your healthcare professionals before embarking on an exercise routine.