September 27, 2021 | Dr. Linda J. Dobberstein, DC, Board Certified in Clinical Nutrition
Nearly 2 billion people across the globe are estimated to have inadequate iodine intake. Of this number, about 300 million are children. This trace mineral is well-known for its role with thyroid health but it also affects your whole body. Despite the implementation of iodized salt decades ago, many individuals still lack adequate iodine intake.
Iodine was discovered in 1809 by French scientists. By 1895, iodine was widely used as a universal remedy for nearly all human ills with extraordinary results. Historical treatment dosages ranged from a few milligrams (mg) to markedly higher doses. After World War II, iodine usage and its recorded medical history have been substantially silenced.
The US RDA for iodine in adult men and women is 150 microgram (mcg) per day. The RDA for women who are pregnant or breastfeeding is 220 – 290 mcg/day. The RDA for infants 0 – 12 months is 110-130 mcg. Children ages 1-13 years is 90 – 120 mcg. This dose is usually sufficient if iodine stores in your body are adequate.
World organizations recommend 1.0 - 1.8 mg of iodine daily for replenishing iodine stores. Higher iodine intake of 1 - 6 mg per day acts as an antioxidant. Individuals with iodine sensitivity or underlying thyroid disease should consult with their health care professional about iodine intake. Iodine excess may be a concern for those with autoimmune thyroid disorders. Too much and too little iodine intake affects health.
Pregnant and Breastfeeding Women
Studies measured dietary iodine in pregnant women in the United States, which showed this population group often lacks adequate iodine intake. Expectant women are considered a high-risk group for iodine deficiency.Prevalence of inadequate iodine intake in women of child-bearing age has actually increased in recent years.
Consequences of insufficient iodine intake during pregnancy affect the unborn child with potential life-long consequences. Risks associated with severe iodine deficiency include neuro-developmental deficits that affect physical and mental development. Iodine deficiency during pregnancy leads to lower intelligence, impaired mental function, stunted growth, delayed sexual maturation, as well as increased risk of stillborn or infant death.
Lab tests for iodine status include urine and blood tests. Urinary iodine concentration assesses more immediate iodine intake. Urinary iodine concentration of 100-199 mcg/L in children and adults, 150-249 mcg/L in pregnant women, and greater than 100 mcg/L in breastfeeding women are considered adequate according to the World Health Organization.
The blood test for thyroglobulin reflects iodine nutrition over a period of months to years. Thyroglobulin is a thyroid protein that is a precursor to thyroid hormone. Thyroglobulin levels increase in response to an enlarged thyroid and with the development of a goiter from insufficient iodine intake.
Research suggests that blood tests of TSH and T4 concentrations do not adequately reflect low iodine status. Other research from a recent NHANES study showed that low iodine and iron levels were associated with increased levels of TSH and reduced free T3. Women were more affected than men. To avoid potential confusion and missed information, test urinary iodine concentration and thyroglobulin levels with TSH, T4, and T3 levels.
Tissues Affected by Iodine
In addition to thyroid hormone production, iodine and its iodide metabolites affect tissues throughout your body. Iodine affects breast tissue, ovaries, pancreas, prostate, and uterus, along with your digestive tract, immune system, and nervous system. Iodine is also taken up by your saliva glands, eyes, skin, and thymus gland. It is needed for hearing and auditory function. Studies show that adequate iodine intake is highly important to maintaining normal breast tissue architecture and function.
Iodine and Thyroid
Iodine is necessary to produce T4 and T3 thyroid hormone and metabolism. More information about iodine and thyroid health may be found at:
Immune and Antioxidant Benefits
Iodine has been used historically for its antiseptic support and other immune benefits. In 1988, a research publication identified the effects of iodine on immune function. Iodine modulated inflammatory responses of granulocytes, a type of immune cell. It increased the movement of granulocytes into areas of inflammation, which increased phagocytosis (engulf/eat) and destruction of bacteria.
Research published in January 2021 showed that iodine activated or inhibited several immune compounds depending on tissue need. Iodine activated Th1 and Th2 immune response. It increased production of natural killer cells and cytokine production as needed for defense. It activated apoptosis, or cell death, in dysregulated cells. As an antioxidant, it deactivated pro-inflammatory pathways. It also modulated mitochondrial function, which also impacted immune regulatory and energetic actions.
Iodine acts as a free radical scavenger to protect cell membranes, proteins, and DNA and down-regulates pro-inflammatory arachidonic acid pathways. Iodine helps alkalinize tissues as it elevates pH. It has been used orally in a mouth rinse or taken orally for immune support.
Iodine directly effects detoxification of halide compounds such as bromides, fluorides, chlorides, and perchlorate jet fuel byproducts along with some heavy metals like mercury and lead. These compounds compete against iodine absorption in cell receptor sites and the thyroid gland. Adequate iodine is essential to protect against exposure of these toxins. To help your body manage detoxification of these compounds, start with very small doses of iodine intake to avoid “detox symptoms”.
Cholesterol and Metabolism
Iodine intake impacts cholesterol metabolism and heart health. A recent study in adults with good thyroid function suggests that low iodine intake poses a risk factor against cardiovascular health. Analysis of the NHANES 2007-2012 population study found that US adults with low urinary iodine concentration had a greater risk for elevated total and LDL cholesterol with lower HDL levels.
Iodine and Diet
Foods that contain iodine include seaweed, fish, dairy, eggs, and enriched breads and pastas. Fruits, vegetables, animal proteins, legumes, etc. contain little to no iodine. Sea salt/Himalayan/Celtic gourmet sea salt does not contain iodine unless it is added. Salt restriction, low salt diet, or use of non-iodized salt is linked with insufficient iodine intake. If you have eliminated eggs, dairy, and/or seafood from your diet, it is likely that your iodine intake is inadequate.
Here are some examples of iodine content in food.
Seaweed, nori 10g 232 mcg
Cod, baked 3 oz 158 mcg
Tuna, canned, 3 oz 7 mcg
Bread, whole wheat, one slice, with added iodate 198 mcg
Egg, hard boiled, 1 large 26 mcg
Yogurt, Greek, plain, nonfat, 1 c 116 mcg
Foods that contain high amounts of goitrogens may worsen iodine deficiency effects. Goitrogens are substances like thiocyanate that interfere with iodine absorption by your thyroid gland. Inadequate iodine absorption can lead to swelling of the thyroid gland and development of a goiter.
Vegetables such as broccoli, Brussels sprouts, cauliflower, cabbage, kale, kohlrabi, rutabaga, soy, spinach, and others contain thiocyanate which blocks iodine uptake and use by the thyroid. Cooking these foods deactivates thyiocyanate.
Ongoing daily consumption of these raw foods like a spinach or kale smoothie or fresh broccoli with your salad every day may contribute to sluggish thyroid function and metabolism when iodine and other nutrients are inadequate. Tolerance of these raw foods and goitrogen-inducing compounds are improved with adequate intake of vitamins A and B12, iodine, iron, selenium, and zinc.
Iodine Works Best with Other Nutrients
Adequate vitamin A and selenium are especially critical for iodine management. B vitamins, vitamin C, magnesium, and other antioxidants are required for iodine metabolism. Adrenal and brain health often also need support for a healthy metabolic balance with thyroid function.
Your thyroid contains about 15-20 mg of iodine when it has been adequately supplied. This is thought to be about 30 percent of the total iodine amount stored in your body. The US RDA is 150 mcg. It takes 1000 mcg to equal 1 mg.
There are nearly 7.9 billion people in 2021. About 2 billion individuals lack adequate iodine intake. Are you one of them?