Which nutrient deficiency causes goitre?

The most common cause of goitre is iodine deficiency.12

Iodine is an essential nutrient required for the production of thyroid hormone. When dietary intake of iodine is insufficient, the body cannot produce adequate levels of thyroid hormone. In response, the pituitary gland increases the secretion of thyrotropin (thyroid-stimulating hormone) to stimulate the thyroid gland. While this mechanism attempts to restore hormone production, it also triggers the growth of thyroid cells, leading to the enlargement of the gland known as goitre.12

This condition is easily preventable through adequate dietary intake of iodine, most commonly achieved by using iodized salt or consuming seafood. Additionally, certain foods known as goitrogens—such as cassava, millet, and cabbage—can inhibit thyroid hormone synthesis and exacerbate the effects of iodine deficiency if consumed as dietary staples.123