This is probably the definitive study on the inverse relation of iodine levels and heart disease:
http://iodineresearch.com/files/cann_20 ... isease.pdf Hypothesis: Dietary Iodine Intake in the Etiology of Cardiovascular Disease
Stephen A. Hoption Cann, PhD
Department of Health Care and Epidemiology, University of British Columbia, Vancouver, British Columbia, CANADA
Key words: atherosclerosis, coronary heart disease, iodine, selenium, thyroid hormones
This paper reviews evidence suggesting that iodine deficiency can have deleterious effects on the cardiovascular
system, and correspondingly, that a higher iodine intake may benefit cardiovascular function.
In recent years, public health bodies have aggressively promoted sodium restriction as a means of reducing
hypertension and the risk of cardiovascular disease. These inducements have led to a general decline in iodine
intake in many developed countries. For example, a United States national health survey conducted in the early
1970s observed that 1 in 40 individuals had urinary iodine levels suggestive of moderate or greater iodine
deficiency; twenty years later, moderate to severe iodine deficiency was observed in 1 in 9 participants.
Regional iodine intake has been shown to be associated with the prevalence of hypothyroidism and
hyperthyroidism, where autoimmune hypothyroidism is the more common of the two in regions with moderate
to high iodine intake. Both of these thyroid abnormalities have been shown to negatively affect cardiovascular
function. Selenium, an important antioxidant in the thyroid and involved in the metabolism of iodine-containing
thyroid hormones, may play an interactive role in the development of these thyroid irregularities, and in turn,
cardiovascular disease. Iodine and iodine-rich foods have long been used as a treatment for hypertension and
cardiovascular disease; yet, modern randomized studies examining the effects of iodine on cardiovascular
disease have not been carried out.
The time has come for investigations of sodium, hypertension, and cardiovascular disease to also consider
the adverse effects that may result from mild or greater iodine deficiency.
Key teaching points:
• Iodine deficiency can cause thyroid dysfunction including hypothyroidism, impaired mental and physical development, loss of
energy, and increased prenatal and infant mortality.
• In recent years, the prevalence of iodine deficiency has increased in many countries that use iodized salt as a dietary source of
iodine.
• The prevalence and incidence of hypothyroidism and hyperthyroidism has been shown to vary with regional iodine intake. Both
thyroid diseases are known to adversely affect cardiovascular function.
• Selenium interacts uniquely with iodine: selenium-containing antioxidants protect the thyroid against oxidative damage during
thyroid hormone synthesis; whereas selenium-containing deiodinases are involved in both activation and inactivation of thyroid
hormones.