An underactive thyroid, also known as hypothyroidism, is a condition in which your thyroid doesn't produce enough hormones for proper functioning, according to MayoClinic.com. In addition to taking synthetic thyroid hormones, people with an underactive thyroid may benefit from avoiding certain foods. These foods may interfere with your body's ability to use synthetic hormones or may further slow your already underactive thyroid. Discuss any dietary changes, as well as any underactive thyroid symptoms, with your physician.
Dark Green Vegetables
Dark green vegetables such as spinach, kale, broccoli and Brussels sprouts can interfere with medication for an underactive thyroid, according to the University of Maryland Medical Center. These vegetables are high in iron, which can prevent your body from absorbing your thyroid medication if you get too much. Avoid eating these vegetables or taking an iron supplement until you have discussed the risks and benefits with your doctor.
Soy Products
Soy-based foods like edamame, tofu and soy milk may prevent your body from absorbing thyroid medication, according to MayoClinic.com. Soy may also contain compounds that further slow down an already sluggish thyroid. Avoiding soy with an underactive thyroid may, therefore, prevent two problems by ensuring both your thyroid and your medication can work at peak performance. Since soy is a common food additive, read food labels carefully to choose soy-free products.
Foods With Fiber
Although some fiber is necessary for digestive health, too much fiber will rob your body of your thyroid medication, preventing you from receiving its full benefits. You can limit the amount of fiber you take by eating smaller portions of grain products and drinking juice rather than eating whole fruits or vegetables. It is best to take thyroid medication on an empty stomach and eat a low-fiber meal an hour later, according to the National Institutes of Health.
