07/20/2026
Heart, Thyroid, Cognition & More! The Iodine Connection
In recent decades, we have seen a steady lowering of sodium (salt) to promote a heart healthier diet. However, many of the things we give up striving for greater health may be contributing to harming other areas. One of those is the iodine connection to thyroid function. Prior to the 1920s and the widespread availability of iodized salt, sections of the country were referred to as the “goiter belt.” Lack of iodine severely impairs thyroid function.
Fast forward to a time of increased blood pressure contributing to the rise in heart disease and we see a shift to reducing salt intakes (and some foods) to limit risks for developing heart disease. Ironically, at the same time we begin to see a rise in thyroid conditions. Please keep in mind iodine is only one of the nutrients needed for a healthy thyroid, but a rather important one.
While dairy products do contain iodine, the plant-based alternatives do not. As many people adopt a dairy-free diet another source of iodine is eliminated. Likewise, the popularity of Himalayan salt has also reduced iodine intake. While it naturally contains trace amounts, it is not enough to sustain thyroid function. Furthermore, the amount of iodine in fruits and vegetables varies depending on the soil's iodine content.
As we move away from processed foods to improve heart and other health functions, we also loose sources of added iodine. For example, plant-based diets have the potential to be low in iodine. Additionally, it is estimated between 1-3 million people are using some version of the Paleo diet. A two-year study found that a paleo diet results in a higher risk of developing an iodine deficiency when compared with a more varied diet,
So where to find the iodine? Seaweed, including kelp, nori, kombu, and wakame, are some of the best food sources of iodine. Unfortunately, the content is highly variable per serving. A 3-oz serving of cod contains almost 100 mcg iodine. Grains and dairy remain sources of iodine as well. A variety of fish and beans also contain iodine. Let us not overlook eggs, seafood, and enriched foods.
Lack of iodine can contribute to a multitude of health issues. Including cognitive decline. Research has found impaired neurodevelopment in children with iodine deficiency. Likewise, deficiency also affects the aging population. Furthermore, iodine deficiency has also been connected to effects on glucose metabolism, lipid metabolism, and obesity. And yes, thyroid dysfunction.
However, over supplementing also causes health issues. Please note many iodine supplements negatively interact with prescription drugs. Recommended daily intake of iodine varies by age ranging from 90 to 290 mcg daily. Considering a banana contains 3mg eating a varied diet containing multiple sources of iodine is essential.
When using an iodine supplement, it is important to first document iodine deficiency. Levels of iodine within the body will directly correlate to amount of supplementation needed. In general, a recommended 150 mcg of potassium iodide is usually sufficient for adults. Again, contact a knowledgeable health practitioner for proper guidance to avoid negative health results.
Dianna Richardson, ND July 2026
References:
Manousou S, Stål M, Larsson C, Mellberg C, Lindahl B, Eggertsen R, Hulthén L, Olsson T, Ryberg M, Sandberg S, Nyström HF. A Paleolithic-type diet results in iodine deficiency: a 2-year randomized trial in postmenopausal obese women. Eur J Clin Nutr. 2018 Jan;72(1):124-129.
NIH (2024). Iodine retrieved from https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
Hatch-McChesney A, Lieberman HR. Iodine and Iodine Deficiency: A Comprehensive Review of a Re-Emerging Issue. Nutrients. 2022 Aug 24;14(17):3474.
Zhang L, Shang F, Liu C and Zhai X (2024) The correlation between iodine and metabolism: a review. Front. Nutr. 11:1346452.
Seo Young Sohn, Kosuke Inoue, Connie M Rhee, Angela M Leung, Risks of Iodine Excess, Endocrine Reviews, Volume 45, Issue 6, December 2024, Pages 858–879.
Sadia, Z., Kamil, K. A., Khurshid, T., & Khan, M. (2025). Reaffirming the role of iodine in cognitive health: a call for lifespan-based public health action. Annals of Medicine & Surgery, 87(12), 7919–7920.
Hoption Cann SA. Hypothesis: dietary iodine intake in the etiology of cardiovascular disease. J Am Coll Nutr. 2006 Feb;25(1):1-11.
