In my article on iodine a few years ago [#125 1 Aug 2011] I hinted that iodized table salt may be inadequate as an iodine source. Lynne Farrow, author of “The Iodine Crisis: What You Don’t Know About Iodine Can Wreck Your Life” (2013) explains why in an essay titled “Debunking ‘Iodized’ Salt”. Farrow gives three reasons why iodized salt is an inadequate source of iodine.
1) Iodine, as potassium iodide, is not stable in salt and sublimates (vaporizes) after opening, especially with high humidity. After about a month, half of the iodine is gone. Who knows how much is left after a few years.
2) Even if the salt is consumed fresh from the factory, only about 10% is absorbed. The sodium in salt competes with iodine for absorption, making salt a questionable food to fortify with iodine.
3) While the iodide form in iodized salt is used by the thyroid and may prevent goiter, it’s not the only form your body needs. Women particularly require the iodine (I2) form for breast and ovarian health.
The amount of iodine in salt is insufficient for several additional reasons. For starters, only about 20% of the salt consumed in North America is iodized. Salt added to processed foods is not iodized. Neither are sea salts or other gourmet salts.
The Canadian RDA of 150mcg for adults is the minimum to prevent goiter in most people. Like the amount of vitamin C needed to prevent scurvy, this amount is much lower than what our bodies need for optimum health. Pregnant women and growing children need sufficient iodine for brain growth. Much higher amounts are required to prevent fibrocystic breast disease and breast cancer.
Many nutritionists are now recommending a minimum of 12.5 mg total of iodide and iodine. They also recommend avoiding sources of the other halogens – bromide (found in commercial flour and baked goods), fluoride and chlorine – which compete with iodine contributing to a deficiency.