Generally, there's no hypothyroidism diet. Although claims about hypothyroidism diets abound, there's no evidence that eating or avoiding certain foods will improve thyroid function in people with hypothyroidism.

However, adequate dietary iodine is essential for normal thyroid function. In developed countries, thyroid disease from iodine deficiency has been nearly eliminated by iodine additives in salt and food. Eating a balanced diet makes taking supplemental iodine unnecessary. In fact, too much iodine can cause hyperthyroidism in some people.

Other supplements such as soy, taken in large amounts, may have an impact on thyroid hormone production but won't cause hypothyroidism in people who are not also iodine deficient.

Avoiding dietary extremes will ensure thyroid health. If you have concerns, talk with your doctor about taking a multivitamin with minerals.

If you have hypothyroidism, take thyroid hormone replacement medication as directed by your doctor — generally with an empty stomach. It's also important to note that too much dietary fiber can impair the absorption of thyroid hormone replacement medication. Certain foods, supplements and medications can have the same effect.

Avoid taking your thyroid hormone at the same time as:

• Walnuts
• Soybean flour
• Cottonseed meal
• Iron supplements or multivitamins containing iron
• Calcium supplements
• Antacids that contain aluminum, magnesium or calcium
• Some ulcer medications, such as sucralfate (Carafate)
• Some cholesterol-lowering drugs, such as those containing cholestyramine (Prevalite) and colestipol (Colestid)

To avoid potential interactions, eat these foods or use these products several hours before or after you take your thyroid medication.

Supplements containing biotin, common in hair and nail preparations, can interfere with the measurement of thyroid hormone. Biotin does not affect thyroid hormone levels, but supplements should be stopped for at least a week before measuring your thyroid function so that your thyroid status is accurately reflected.