Is there any way to keep thyroid glands healthy, such as supplements?

Iodine rich foods: There is definitely an association with benign enlargement of the thyroid gland, called a goiter, and a low iodine diet. For this reason, iodine was added to table salt in many areas. Japanese are taking iodine supplements in an attempt to protect the gland from radiation exposure. Reports of the value of both practices are mixed: goiter improves, but overproduction of thyroid hormone can result.

No: most common cause of hypothyroidism is Hashimoto thyroiditis. This is not influenced by the diet.