Iodine is a trace mineral which is required only in small doses. We may not need a lot of it, but it’s still incredibly important to the thyroid gland to aid in producing thyroid hormone. Iodine deficiency is strongly correlated to thyroid diseases, including goiter, thyroid cancer and thyroid nodules. A nodule is an abnormal cluster of cells on the thyroid gland; they can be completely benign, but a small percentage of the time they are linked to cancer. They can also be a sign of hypothyroidism when other symptoms are present, such as fatigue, weight gain, dry coarse hair, and sensitivity to cold temperatures.

Iodine can be obtained from foods such as seaweed, wild-caught fish, dairy products and green vegetables. Typically the standard American diet doesn’t provide enough iodine, because of food selection and because much of the soil where plants are grown has been found to be deficient in iodine. Not only do we not consume enough iodine in our diet, its absorption is blocked by certain common environmental toxins, particularly those containing bromine (found in plastic, enriched flour, and other sources). This combination of factors explains why so many people have become iodine deficient, and is what led to iodine fortification in table salt. Iodine fortification programs in the US were initiated in the 1920s, a time when iodine deficiency became noticeable based on high rates of goiter. Goiter is an enlargement of the thyroid gland due to insufficient iodine.

China did not initiate iodine fortification until 1995, in efforts to help resolve a increasing rate of deficiency in that country. Because their fortification program is relatively new, scientists are still conducting research to evaluate the success of their program. Recently, a study was published which summarized the outcomes of 43 Chinese research studies on iodine, as a means to determine if iodine supplementation was having an overall positive effect on the incidence of thyroid disease in that country.

The outcome of this research review revealed several important concepts about thyroid disease and iodine fortification. It was determined that thyroid nodules were the most common of all possible thyroid diseases. The analysis categorized all participants from the studies into one of three groups: high, medium, and low iodine levels (as measured in urine). Thyroid nodules were found in 22% and 25% of the participants in the low- and medium- level iodine groups. The group that had high iodine levels had a significantly lower rate, at approximately 7%.

The second most common type of thyroid disease was found to be subclinical hypothyroidism. In this condition, rates were lower in the group with medium levels of iodine, as compared to the lowest and highest iodine levels which experienced more subclinical hypothyroidism.

Overall, iodine fortification programs in most countries have proven to be effective, but iodine deficiency is still possible. If you are suffering from any of the hypothyroid symptoms listed previously, you may want to first check your iodine levels, even if you have normal thyroid lab tests. Iodine supplementation can be a simple and inexpensive solution. It’s recommended to also take selenium with iodine to help maintain mineral balance.

If you have adequate iodine and selenium levels and still can’t figure out why you have hypothyroid symptoms, be sure to check your body temperature, as consistently low temperatures are a hallmark of Wilson’s Temperature Syndrome (WTS). Read more about body temperature and WTS HERE!

Medicine (Baltimore). 2017 Jun;96(25):e7279. A PRISMA-compliant systematic review and meta-analysis of the relationship between thyroid disease and different levels of iodine intake in mainland China. Weng W1, Dong M, Zhan J, Yang J, Zhang B, Zhao X.