An enlargement of the thyroid gland that is usually visible as a swelling in the anterior portion of the neck. Simple goitre occurs when the thyroid gland is unable to meet the demands of the body (for example iodine deficiency). The thyroid gland compensates by enlarging. Some foods such as cabbage, soybeans, peanuts, peaches, radishes and spinach contain substances that decrease thyroid production. Some medications such as lithium, cobalt and phenylbutazone can also decrease thyroid hormone production.