Yesterday I mentioned that sea vegetables are a great source of iodine. “But what is iodine?” many emailers asked. Well, dear friends, iodine is elemental. Let’s take a trip through the land of iodine to learn what it is, what it does for the human body and whether you should make an effort to get more iodine in your diet.

What is Iodine?

Iodine is a highly water-soluble trace element that’s rare in the earth’s crust, but fairly prevalent in its seas. Our bodies require it, for several reasons. Our thyroid glands use it to make thyroid hormones (T3 molecular weight is 59% iodine; T4 molecular weight, 65%), and a severe deficiency can manifest in the development of goiter, which is the thyroid gland swelling up in an attempt to keep up the pace of iodine uptake from the blood and thyroid hormone production. Lovely stuff, eh? Other common symptoms of iodine deficiency include hypothyroidism and hyperthyroidism. It can also increase the incidence of early mental retardation (iodine deficiency-related retardation is the most preventable kind, in fact), and even stunted infant brain development, provided the kid even makes it out alive: iodine deficient pregnant women are at a higher risk for miscarriages and stillbirths.

Today, most table salt has been iodized, and most processed food is in turn made with plenty of iodized salt. As Richard pointed out a few months back, an unintended benefit of the SAD may be the adequate intake of iodine! Ironically, hyper conscious eaters who eschew all processed foods and sprinkle shavings of the purest Himalayan salt blocks (reconstituted, perhaps, from the sweaty pits of organic Sherpas) on their meals may be missing out on iodine. Sea salt does contain trace amounts of iodine, being from the sea, but what’s there degrades pretty rapidly. Subsisting on sea salt alone is almost certainly inadequate for iodine intake. If you avoid processed food (as you should), be sure to eat sea vegetation from time to time.