In one of my recent presentations I was discussing low salt or salt restricted diets and the need for such with certain health conditions. I was asked if salt is restricted what about iodine and are there other sources? Excellent question!
Iodine is a critical micronutrient in the human diet—that is, something our bodies can't synthesize that we have to rely on food to obtain.
Iodine is a trace element that is naturally present in some foods, added to others, and available as a dietary supplement. Iodine is an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Thyroid hormones regulate many important biochemical reactions, including protein synthesis and enzymatic activity, and are critical determinants of metabolic activity. They are also required for proper skeletal and central nervous system development in fetuses and infants.
Thyroid function is primarily regulated by thyroid-stimulating hormone (TSH), also known as thyrotropin. It is secreted by the pituitary gland to control thyroid hormone production and secretion, thereby protecting the body from hypothyroidism and hyperthyroidism. TSH secretion increases thyroidal uptake of iodine and stimulates the synthesis and release of T3 and T4. In the absence of sufficient iodine, TSH levels remain elevated, leading to goiter, an enlargement of the thyroid gland that reflects the body’s attempt to trap more iodine from the circulation and produce thyroid hormones. (NIH Dietary Supplement Sept. 26, 2018)
—and it's been added to salt (in the form of potassium iodide) since 1924. Originally, iodization was adopted to reduce the incidence of goiter.
Thanks to a more national food supply, iodized salt and other factors, iodine deficiency is now uncommon in North America
What about “healthy salts”……
Although pink Himalayan salt may naturally contain some iodine, it most likely contains less iodine than iodized salt. Therefore, those who have iodine deficiency or are at risk of deficiency may need to source iodine elsewhere if using pink salt instead of table salt.
Sea salt contains minimal amounts of iodine naturally. Sea salt and table salt have the same basic nutritional value, despite the fact that sea salt is often promoted as being healthier. Sea salt and table salt contain comparable amounts of sodium by weight. Sea salt often undergoes minimal processing and contains small amounts of magnesium, potassium and calcium, according to the American Heart Association, therefore thought to be healthier. My thinking is maybe we use less of it because of sea salts heightened taste profile. Celtic Sea Salt® Gourmet Seaweed Seasoning contains 350 mcg of iodine per ¼ tsp. It's a truly natural, iodine-rich sea salt.
Eating too much of any kind of salt, including sea salt, can increase your blood pressure and your risk for heart disease. The Academy of Nutrition and Dietetics notes that 1/4 teaspoon of sea salt often contains between 400 and 590 milligrams of sodium. The American Heart Association recommendation is to consume no more than 1,500 milligrams of sodium daily. Most American diets contain 4,000 mg of sodium daily. Next time you’re in the grocery store check the sodium label on a can of soup!
Iodine is found primarily in seaweed, seafood, and dairy. The following table list selected food sources and their iodine content in micrograms.