There is no such thing as a hypothyroidism diet, but there are some basic rules concerning foods that can make your symptoms better or worse – and some of them may surprise you! Hypothyroidism occurs when you don’t produce enough thyroid hormone. It may also be called underactive thyroid, low thyroid or Hashimoto's thyroiditis. Women and people older than 50 are disproportionately affected by hypothyroidism. Symptoms may include fatigue, weight gain, paleness and dry skin. Treatment typically involves the synthetic thyroid hormone levothyroxine, and many foods, medications and supplements can interfere with this hormone. Underactive Thyroid Diet Do’s If you have an underactive thyroid gland, you should: Snack on seaweed. Iodine deficiency can lead to hypothyroidism. Fortunately, the advent of iodized salt has dramatically reduced the incidence of iodine deficiency in the US, but not elsewhere. The body does not make iodine, which is needed to produce thyroid hormones. Good sources include cheese, eggs, ice cream and seaweed, including kelp. Seaweed snacks are all the rage today and can be a healthy, low-fat alternative to chips. It's also rich in selenium, which enhances your body' thyroid hormone production. Ask your doctor how much iodine you should include in your diet. Double up on dairy. Many dairy foods including low-fat milk and yogurt are fortified with vitamin D. Some research suggests people with hypothyroidism may be D-deficient. Vitamin D is often called the sunshine vitamin because your body produces it when exposed to sunlight. It can be hard to get all the D you need from food. A simple blood test can tell you where you stand, and your doctor can tell you how much more D you need and how to best get it. Go fish. About 40% of people with hypothyroidism are deficient in vitamin B-12, according to research. Dietary sources include fish, poultry, liver, meat, eggs, seafood and dairy products. Fortified cereals are also rich in vitamin B12. Talk to your doctor about your B12 levels, your diet and whether or not you also need to take supplements of this important vitamin. Bonus: Many foods rich in B12 are also teeming with selenium (a mineral that helps your thyroid do its job and do it well) and omega-3 fatty acids, which can improve some of your hypothyroid symptoms. Underactive Thyroid Diet Don’ts If you have an underactive thyroid gland, you should: Skip the soy. Soy protein, found in tofu, edamame and many other foods, can prevent your body from absorbing the hormone you take to treat your underactive thyroid gland – especially if it’s eaten within one hour of taking your medicine. Walnuts and cottonseed meal can also affect your medication. Ask your doctor for specific advice based on your diet preferences, as well as your current treatment plan. Banish the broccoli. Broccoli is rich in potent nutrients that can help reduce risk of heart disease and cancer, but for people with underactive thyroid glands, broccoli and other cruciferous veggies can interfere with thyroid function. The rather lengthy list includes cabbage, Brussels sprouts, cauliflower, kale, spinach and turnips. These veggies possess goitrogens, or substances that can cause enlargement of the thyroid gland. Cooking your vegetables reduces the number of these potentially damaging substances in otherwise healthy vegetables. Talk to your doctor for personalized advice on how to eat your veggies. Watch out for whole grains. Whole grains are rich in fiber, which does offer a multitude of benefits, including reduced risk of heart disease and certain cancers, as well as improved digestive health, but too much dietary fiber can impair the absorption of your synthetic thyroid hormone. How much is too much? That depends. Talk to your doctor about the best way to balance the risks and benefits of fiber in your diet. Shades of Gray Some foods don’t fit neatly into do or don’t categories. For example, soymilk and soy sauce are good sources of iodine, but soy products and your thyroid hormone may not mix. What’s more, whole-grain breads are rich in vitamin B12 but can affect how you absorb your medication. Discuss any concerns you have with your doctor or a nutritionist. He or she can also give you advice on how and when to take vitamins and medications so that they won’t interfere with your thyroid pills.