Diet and epithelial cancer of the thyroid gland

Enhanced secretion of thyroid stimulating hormone (TSH) has been linked with increased risk of thyroid carcinoma. Diet can increase TSH secretion in various ways: 1) low iodine intake, 2) high goitrogen intake, especially in subjects living in iodine-deficiency areas and 3) direct stimulation of anterior pituitary gland. Excessive iodine intake, however, has also been shown to increase risk of goitre and, perhaps, also thyroid carcinoma. Epidemiological evidence on the role of diet in the etiology of thyroid carcinoma is reviewed here. Ad hoc studies in affluent countries are few and often conflicting. A case-control study conducted in the North of Italy suggests that perhaps dietary aspects other than iodine or goitrogens (i.e. fresh fruit and vegetables and animal fat) may be involved.