Healthy thyroids, healthy people

The thyroid gland is a hormone producing organ that is part of the endocrine system. You can read more about the endocrine system via the following links:

• Endocrine system (KidsHealth, Nemours Foundation)

• Hormonal (endocrine) system (Better Health)

• Anatomy of the Endocrine System (Johns Hopkins Medicine)

• Endocrine glands and their hormones (Healthdirect Australia)

The thyroid gland produces hormones, which perform various roles in the body. Information about the thyroid gland, its hormones and its roles can be found on the following web pages:

• Thyroid gland and thyroid hormones (myDr)

• How does the thyroid work? (Institute for Quality and Efficiency in Health Care)

• Thyroid Gland (Encyclopædia Britannica)

• Thyroid Gland (Hormones Australia)

While a healthy diet combined with exercise is necessary for general health, the diet needs to contain some specific, essential nutrients to allow the thyroid to produce thyroid hormones and to enable those hormones to perform their functions in the body. These nutrients are:

Iodine

The most important mineral for thyroid function is iodine. It is necessary for the production of thyroid hormones.

Iodine deficiency can cause goitre, hypothyroidism and cretinism (i.e., severe hypothyroidism at the time of birth, leading to stunted physical and mental growth).

Iodine excess can cause goitre, hyperthyroidism (thyrotoxicosis, i.e. excess thyroid hormone levels) and nodule formation, particularly in people with underlying thyroid conditions. 

Selenium

Selenium is not only an important anti-oxidant that protects the thyroid against damage caused by free radicals; it is also crucial for the synthesis of thyroid hormones by the thyroid gland as well as the conversion of the thyroid hormone T4 into the more active hormone T3 by specific enzymes called iodothyronine deiodinases.

Selenium deficiency aggravates the consequences of iodine deficiency and contributes to the development of goitre, hypothyroidism and cretinism.

Selenium excess is toxic.

Other important nutrients

Iron, vitamin A and zinc also play an important role in the synthesis of thyroid hormones by the thyroid gland. If the diet is lacking sufficient amounts of these nutrients, thyroid function may be impaired, particularly in combination with iodine deficiency.

Recommended dietary intake (RDI) and food sources

For information about the recommended dietary intake (RDI) and food sources of these nutrients, see these pages on the NZ Nutrition Foundation website: iodine, selenium, iron, vitamin A and zinc.