Iodine might not be the first thing you think of when you list off critical nutrients for health and wellbeing. But this trace mineral is critical to thyroid function, immune health, nervous system regulation, breast health, and more. It’s also crucial for healthy pregnancy and fetal development. It has remarkable antiseptic properties and is still used to disinfect wounds and prepare skin before surgery.
In this article we’ll review the many uses of iodine, benefits, symptoms of deficiency, sources of iodine, and more.
What is Iodine?
Iodine (I) is one of the nine trace minerals our bodies need to facilitate enzymatic reactions, produce hormones, enable cellular communication, and accomplish dozens of other functions. While we don’t need as much iodine as we need other major minerals like magnesium and calcium, iodine is still essential to our health, particularly thyroid health.
Unlike some nutrients, our bodies can not synthesize iodine on its own. We have to ingest iodine through our diet and supplementation, if needed, to get enough. However, iodine is also a nutrient that has a very narrow range of safety, meaning that it can be quite easy to get too much, especially when supplementing.
Iodide vs Iodine
Iodide is a reduced salt form of iodine that is taken up by the body and used in various biological processes, like hormone synthesis. Iodide is absorbed through the stomach and the first part of the small intestine, the duodenum . Once in circulation, there is a transport protein called the sodium-iodide symporter that is present in several tissues—for example, the thyroid, cervix, breast tissue, and salivary glands—that allows iodine to be used in the cell .
When you buy iodized salt, what you often get is salt combined with potassium iodide. Many countries—including the United States, Canada—and dozens of others, have had salt iodization programs since the 1920s to prevent widespread deficiency in the general population. However, this is still optional for salt manufacturers. Many processed food manufacturers, where most Americans get their salt intake, do not add iodide to their salt. If you use sea salt, kosher salt, Himalayan salt, etc., these salts are not iodized either, though they do contain some trace minerals.
The main benefits of iodine are maintaining thyroid health, immune function, and brain and nervous system support. Let’s take a closer look at each of these benefits.
Iodine for Thyroid Health
One of iodine’s biggest roles in the body is to support the thyroid in producing thyroid hormones, TSH and its active metabolites T3 and T4.
However, maintaining optimal iodine requirements can be a very delicate balance to achieve. The thyroid also requires selenium to use iodine for thyroid hormone synthesis, so selenium and iodine levels should always be considered together when evaluating supplementation for thyroid health. 
Iodine for Fetal Development
One time where iodine needs are more pronounced is during pregnancy. Iodine is essential for fetal development, particularly for fetal thyroid gland development. Also, during early pregnancy, the fetus depends entirely on the mother’s thyroid hormone production. Production of T4 increases by 50% during pregnancy, requiring an increase in iodine as well. The RDA of iodine for pregnant women increases from 150 to 220 mcg/day, (and the RDA represents the absolute minimum requirement for function, so your individual needs may be higher.) 
Severe deficiency can also contribute to diminished cognitive and neural development in infants and children .
Iodine for Immune Function
Iodine is also critical for proper immune function. Besides being inherently antiseptic, killing all single-celled organisms, iodine and thyroid hormone together appear to provide constant surveillance against abnormal cell development. It also protects against abnormal bacterial growth in the stomach such as H. Pylori overgrowth. Iodine can also coat and neutralize both biological and chemical toxins.
As for the immune system itself, iodine seems to increase immune cell function. This effect is due to iodine itself, rather than an increased production in thyroid hormones . However, additional research shows that, once again, too much iodine can easily cause immune system dysfunction .
Iodine for Fibrocystic Breasts
Iodine deficiency is indicated in women who have fibroids, non-cancerous lumps, in their breast tissue. These abnormal growths usually appear and disappear based on the menstrual cycle, or they may build up over time. Since iodine protects against abnormal cell development and proliferation, adequate iodine levels may prevent these fibroids from occurring .
Iodine for Nervous System and Brain Health
Many parts of the brain appear to be affected by a lack of iodine, including the hippocampus, neurotransmitters, the protective myelin that surrounds our nerves, and the process of cognition itself. Further research needs to be done on iodine’s role in brain health, but we can surmise that maintaining good iodine status is supportive of nervous system and brain health .
Iodine deficiency is actually very common, especially among women since it is present in the female body in the mammary tissue and cervix in addition to the thyroid and salivary glands.
You may be more susceptible to iodine deficiency if you :
- Don’t consume iodized salt
- Are pregnant
- Are vegan or do not consume many animal products
- Live in a region with iodine-deficient soils
- Consume goitrogen-containing foods (foods that interfere with iodine uptake in the thyroid).
- Sensitivity to cold
- Low thyroid hormone production/conversion
- Weight gain
- Dry skin
- Goiter (an enlarged thyroid)
- Pregnancy-related issues, including impaired fetal brain and thyroid development.
Sources of Iodine
You can get iodine from your diet as well as through supplementation.
Iodine Rich Foods
Healthy food sources of Iodine include :
- Seaweed (nori)
- Seafood: fish, oysters
- Dairy: milk, yogurt, cheese
- Beef liver.
Unless they are processed and iodine is added, plant-based foods are not very good sources of iodine (except for seaweed!). If you are generally healthy and following a whole-foods based diet, you can get adequate iodine intake from the foods above.
Iodine supplements can benefit those who are deficient or low in iodine due to a thyroid condition, pregnancy, veganism or low animal food intake, etc. However, it’s always a good idea to work with a practitioner before starting to take iodine if you have a preexisting condition.
With BodyBio Liquid Iodine, you can also use your sense of taste to test whether iodine supplementation is right for you. Simply add the recommended number of drops to an 8 oz. glass of water, swish and swallow, and observe what you taste. If you experience a sweet taste or no taste, it is safe to continue taking iodine and your body is actually craving that mineral. If you experience a foul taste, discontinue––your body does not want more iodine right now. Retest periodically to see whether you need to adjust your dose or stop altogether.
The Bottom Line on Iodine
Iodine is a critically needed mineral to support thyroid hormone production, immune function, and nervous system and brain health. Women especially need adequate presence of this trace mineral, due to its use in breast tissue and the cervix. Yet, it is one of the most finicky nutrients to supplement; too much or too little can easily cause problems and symptoms, including exacerbating hypothyroidism.When supplementing with Bodybio Liquid Minerals, you can use your sense of taste to determine what dose you need and easily adjust as you go. Learn more about BodyBio Liquid Iodine here.