The comment of Cann et al suggesting that a reduction in dietary salt intake may occur at the expense of iodine intake deserves to be scrutinized carefully. The purpose of our editorial was to recognize possible harmful effects of an excessive dietary sodium intake on the cardiovascular system.1 Cann et al are rightly concerned that the practice of supplying most of our iodine needs by supplementing table salt could potentially pose a dilemma that may be worth consideration by public health authorities. We also agree with the authors that hypothyroidism, overt or subclinical, can be an independent risk factor for atherosclerosis and coronary heart disease. However, iodine deficiency is by no means synonymous with hypothyroidism. Most patients who have hypothyroidism do not have iodine deficiency, and only the most severe form of iodine deficiency leads to hypothyroidism. The evidence that iodine should be considered as "an alternative treatment for cardiovascular disease and control of hypertension" is rather shaky. The authors quote 3 articles, one of which2 deals with the effects of iodine baths on central hemodynamics, and the other 2 studies3,4 are thinly veiled advertisements for a health spa (Bad Hall) in Austria. In this spa, most patients vacation at taxpayers' expense to take a daily bath in iodinated saline. According to these studies, the "badekur" supposedly has been documented to be beneficial for hypertension, atherosclerosis, angina pectoris, hyperlipidemia, diabetes, peripheral vascular disease, varicosis, and thrombophlebitis, among others. Specifically, the authors found an average maximal decrease in blood pressure of 42.9/18.6 mm Hg within 10 minutes of immersion into the bath. Not only does the iodine bath have a good effect on cardiovascular disease, but these studies also point out that it has been shown to help in patients with respiratory problems, such as acute or chronic bronchitis, asthma, and sinusitis; musculoskeletal diseases, such as degenerative joint disease, osteoporosis, low back pain, and parkinsonism; in a wide variety of eye disorders ranging from cataracts to macular degeneration; and in women with infertility and other gynecologic disorders. Since these wonderful results are achieved by daily immersion in an iodine bath, it seems to be a great leap of faith to conclude from these "studies" that iodine taken orally should be used as a treatment for hypertensive cardiovascular disease. We also remain skeptical that moderate iodine deficiency per se should be considered as a "risk for cardiovascular disease morbidity and mortality."
Messerli FH, Schmieder RE. Iodized Salt and Hypertension—Reply. Arch Intern Med. 2002;162(1):105. doi: