Foods to avoid with underactive thyroid

The thyroid regulates many functions in the body and when it is not working properly it throws off metabolism. An underactive thyroid (also known as hypothyroid) can cause many symptoms from fatigue to weight gain. It can even cause cognitive problems and depression.

Thyroid hormone medication is usually given to regulate the thyroid levels, but avoiding certain foods can also help an underactive thyroid.

Sugar & Caffeine

Excess sugar can be harmful to the thyroid gland. High sugar foods should be avoided with an underactive thyroid. Caffeine, which is found in coffee and chocolate, is also something to try not to consume a lot of when you have hypothyroidism. Even though caffeine keeps you more alert, it can slow down the thyroid function.

Milk Products

The casein in milk products can cause harm to the endocrine system and throw off the thyroid hormone in the body. There is also the question of the antibiotics and hormones given to cows which are found in milk and can interfere with the entire endocrine system.


Food high in iron (like spinach) should be avoided with hypothyroidism. Iron supplements should also be taken with care. Mercury is also bad for those with an underactive thyroid as it can block the thyroid hormone production. Calcium, magnesium and aluminium can also interfere with thyroid function if taken in excess.


Goitrogen is a substance that can block absorbance of iodine, which helps in thyroid function. It is found in a number of vegetables (cabbage, broccoli, cauliflower, turnip) as well as in pine nuts, soybeans and peanuts. Cooking these foods helps to suppress the goitrogens so if you have an underactive thyroid and can't avoid them, be sure to note eat them raw. Peanut butter is better than raw peanuts for those with hypothyroid.


Thyroid levels can change constantly. They should be monitored by a physician with regular bloodwork for accurate readings and to determine if medication needs to be adjusted after dietary changes are made.