Iodine deficiency is tied to sluggish thyroid, weight gain, estrogen dominance, low iq, dry skin and brittle hair and nails along with digestive issues incl. constipation. Yes, none of these are very sexy admittedly. But fact is we have become a generation characterized by exactly these things. So it is not surprising, that iodine deficiency is epidemic. (1) The book by Dr. David Brownstein, Iodine: Why You Need It and Why You Can't Live Without It, sums up its importance:"Iodine is the most misunderstood nutrient. After 12 years of practicing medicine, I can say that it is impossible to achieve your optimal health if you do not have adequate iodine levels. I have yet to see any item that is more important for promoting health than iodine." Now we might think it is as simple as just taking iodine then, if we are deficient. That, however, is not the case. You will need to assess whether you have the nutrients involved in proper absorption of iodine i.e. selenium, magnesium, iron, tyrosine and vitamin A. Even if you check off these nutrients, there is still a chance, you won’t absorb iodine properly and will waste years trying to saturate your body’s need for this essential nutrient without any luck. This happens if you have toxic levels of certain chemicals. Perchlorate, thiocyanate and nitrate (called as major Sodium-Iodide Symporter (NIS) inhibitors) are known to competitively inhibit iodide uptake by the thyroid gland and thus, human exposure to major NIS inhibitors is a public health concern (2). NIS is something you want to pay attention to, as this symporter is responsible for the uptake of iodine in the body. If something is blocking the symporter, you will not benefit from the iodine or other supplements you might be taking. This is why I always test clients for their chemical toxic load when treating them. Simply focusing on knowing their nutrient deficiencies is not enough and will not identify the underlying reasons of why you are not absorbing your nutrients.