Did you know that iodine deficiency is now regarded by the World Health Organization (WHO) as the most prevalent and easily preventable case of impaired cognitive development in children in the world? There are at least 30 million suffering from this preventable condition.
Iodine is a trace mineral and an essential component of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). These hormones regulate the metabolic activities of most cells and play a vital role in the process of early growth and development of most organs, especially the brain. Inadequate intake of iodine-rich foods leads to insufficient production of these hormones, which adversely affect the muscle, heart, liver, kidney and the developing brain. (1)
Here are iodine deficiency statistics that may surprise you:
- The National Health Nutritional Examination Survey reported that iodine levels have decreased by 50 percent in the last 30 years.
- More than 96 percent of over 5,000 patients tested were iodine-deficient in a clinical study conducted by thyroid expert Dr. David Brownstein. (2)
- According to the WHO, iodine deficiency affects 72 percent of the world’s population.
- In 2011, 70 percent of households globally had access to iodized salt (3)
The term iodine deficiency disorders has been coined to represent the different array of disorder that result from iodine deficiency in a population. (4) These disorders are all preventable if the appropriate dose of iodine is administered. Common disorders that result from iodine deficiency are hypothyroidism, increased cholesterol levels, endemic goiter, cretinism, decreased fertility rate, increased infant mortality, fibrocystic breast disease, atherosclerosis and breast cancer. (5)
Iodine Deficiency Symptoms
Clinical signs and symptoms of iodine deficiency include: (6)
- Difficulty losing weight
- Dry skin
- Lethargy or fatigue
- Memory problems
- Menstrual problems
- Recurrent infections
- Sensitivity to cold
- Cold hands and feet
- Brain fog
- Thinning hair
- Shortness of breath
- Impaired kidney function
- Muscle weakness and joint stiffness
6 Possible Risk Factors Linked to Iodine Deficiency
When iodine intake becomes severely low, the thyroid compensates for the decreased levels by developing a swollen thyroid gland with nodules, known as a goiter, in order to absorb as much available iodine. The FDA currently has set recommended daily allowance (RDA) for iodine at 150 micrograms, which is efficient enough to eliminate goiters that are prevalent in iodine-deficient areas. The following are potential risk factors that may lead to iodine deficiency. (7)
1. Low Dietary Iodine
Soils from mountainous area — such as the Alps, Andes and Himalayas — and areas with frequent flooding are likely to be deficient in iodine. Food grown in iodine-deficient soils rarely provide enough iodine to the livestock and population inhabiting there.
Unlike nutrients such as calcium, iron or vitamins, iodine does not occur naturally in specific foods; rather, it is present in the soil and ingested through foods grown on that soil. In the early 1920s, Switzerland was the first country to fortify table salt with iodine to control cretinism and endemic goiter. In the 1970s and 1980s, controlled studies showed that iodine supplementation before and during pregnancy not only improved cognitive function in the rest of the population, but eliminated new cases of cretinism.
Iodine is obtained primarily through diet but can be obtained from iodine supplementation. (8) In food that is found primarily in sea life, iodine is absorbed into the body through the consumption of sea vegetables and seafood. Other food sources, such as nuts, seeds, beans, turnips, garlic and onions, are good sources, provided that the soil contains sufficient quantities of iodine. (9)
2. Selenium Deficiency
Iodine deficiency, coupled with selenium deficiency, is likely to lead into thyroid imbalance. One of the more serious manifestations of thyroid imbalance is a goiter. In many individuals who are diagnosed with iodine deficiency, studies have shown some may have selenium deficiency as well. The thyroid gland needs both selenium and iodine to produce adequate levels of thyroid hormones, but when there’s a deficiency in one or both, your body has low thyroid hormone levels. That’s why adequate iodine levels are needed for adequate thyroid function.
Iodine is known for playing a vital role in thyroid health while benefit-rich selenium is critical in recycling iodine. When selenium levels are low, the thyroid will work harder to produce thyroid hormones, and the body will have a difficult time changing these hormones into forms utilized by cells. It’s important to treat both deficits in order to re-establish normal thyroid health. (10)
According to the journal Pediatrics, about one-third of pregnant women in the U.S. are iodine-deficient. Currently, only about 15 percent of breastfeeding and pregnant women take iodine supplements. (11)
Supplemental iodine is commonly in the form of sodium iodide or potassium. Severe iodine deficiency is associated with stunted mental and physical growth, and even marginal iodine deficiency can impair brain functioning in infants. Supplementation should include at least 150 micrograms of iodide, and use iodized table salt. Combined intake from supplements and food should be 290 to 1,100 micrograms a day. Potassium iodine is the preferred form. (12)
4. Tobacco Smoke
Tobacco smoke contains a compound called thiocyanate. The inhibitory effects of thiocyanate on the uptake of iodide is through competitive inhibition of the iodide transport mechanism and may be responsible for the reduction of levels. Other substances in tobacco smoke that can impair thyroid function are hydroxypyridine metabolites, nicotine and benzapyrenes. Tobacco smoke not only has an effect on thyroid function, but can also block thyroid hormone action. (13)
5. Fluoridated and Chlorinated Water
Tap water contains fluoride and chlorine, which inhibit the absorption of iodine. In a study where researchers used the Wechsler Intelligence Test to determine the IQs of a total of 329 eight- to 14-year-old children living in nine high-fluoride, low-iodine villages and in seven villages that had only low levels of iodine. As discovered, the IQs of children from the high-fluoride, low-iodine villages were lower than those from the villages with low iodine alone. (14)
6. Goitrogen Foods
Eating raw vegetables in the Brassica family (cauliflower, broccoli, kale, cabbage, soy, Brussels sprouts) can impact thyroid function because they contain goitrogens, molecules that impair peroxidase. Steaming these cruciferous vegetables until fully cooked before consumption breaks the goitrogens down. People with iodine deficiency are at risk when consuming these foods. (15)
How You Can Prevent an Iodine Deficiency
Best Sources of Iodine
The RDA for iodine is as follows: (16)
- 1–8 years old — 90 micrograms every day
- 9–13 years old — 120 micrograms every day
- 14+ years old — 150 micrograms every day
- Pregnant or breastfeeding mothers — 290 micrograms every day
Seaweed is one of the best food sources of iodine, but it’s highly variable in its content. Examples include arame, kombu, wakame, kelp and hijiki. Kelp has the highest amount of iodine of any food in the world.
Other good sources of iodine include seafood, dairy products (usually due to the use of iodine feed supplements and iodophor sanitizing agents in the dairy industry) and eggs. Dairy products, especially raw milk and grain products, are the major contributors of iodine to the American diet. Iodine is also present in infant formulas and human breast milk.
Vegetables and fruit iodine content varies, depending upon the iodine content in the soil, irrigation practices and fertilizer that was used. Iodine concentrations in plants can vary in range as little as 10 mcg/kg to 1 mg/kg dry weight. This variability influences the iodine content of animal products and meat because it affects the iodine content of foods that the animals consume. (17)
Food Sources High in Iodine
Based upon micrograms per serving and daily value (DV) of iodine, the top food sources of iodine include:
- Seaweed — Whole or 1 sheet: 16 to 2,984 micrograms (11 percent to 1,989 percent)
- Baked Cod — 3 ounces: 99 micrograms (66 percent)
- Cranberries — 1 ounce: 90 micrograms (60 percent)
- Plain Low-Fat Yogurt — 1 cup: 75 micrograms (50 percent)
- Baked Potato — 1 medium: 60 micrograms (40 percent)
- Raw Milk — 1 cup: 56 micrograms (37 percent)
- Shrimp — 3 ounces: 35 micrograms (23 percent)
- Navy Beans — ½ cup: 32 micrograms (21 percent)
- Egg — 1 large egg: 24 micrograms (16 percent)
- Dried Prunes — 5 prunes: 13 micrograms (9 percent)
Iodine Supplements and Iodine Salts
Salt iodization, also known as universal salt iodization, programs are put into place in more than 70 countries, including the U.S. and Canada, and 70 percent of households worldwide use iodized salt. The intention of U.S. manufacturers iodizing table salt in the 1920s was to prevent iodine deficiencies. Potassium iodide and cuprous iodine have been approved by the U.S. Food and Drug Administration (FDA) for salt iodization, while WHO recommends potassium iodate due to it having greater stability.
In the United States, iodized salt contains 45 micrograms iodine per gram of salt, which can be found in one-eighth to one-fourth teaspoon. Non-iodized salt is almost always used by food manufacturers, considering the majority of the salt intake comes from processed foods. (18)
This is one of the reasons, however, that I recommend that you use benefit-rich sea salt instead and get your iodine through it, certain foods and supplementation rather than iodizing table salt. Sea salt (Himalayan or celtic salt) contains more than 60 trace minerals and doesn’t pose a risk for overconsuming iodine like table salt can. It’s more beneficial and natural, plus it tastes better.
Furthermore, the benefits of universal salt iodization (USI) still require more research. Research published in the journal Nutrients examined a national cross-sectional study of iodine status among school-aged children in Tunisia, a country that adopted USD two decades ago. The researchers concluded: (19)
Our adequacy assessment of the Tunisian USI program showed that, regarding the UIC impact indicator, the program achieved its objectives: ID national rates are now well below the target criteria of WHO certification (though with important geographic disparities). On the other hand, our study underlined that the coverage of households by adequately iodized salt, falls short of the target of certification. This inadequacy, due to a large variability of salt iodine content, also has adverse consequences, in that a non-negligible proportion of the population features an excess of iodine.
Most of the multivitamin/mineral supplements contain the forms of sodium iodide or potassium iodine. Dietary supplements of iodine-containing kelp or iodine are also available.
8 Benefits of Iodine
1. Controls Metabolic Rate
Iodine influences greatly the functioning of the thyroid glands by helping with the production of hormones directly responsible for controlling the body’s base metabolic rate. Metabolic rate ensures the efficiency of the body’s organ systems and biochemical processes, including sleep cycle, absorption of food and transformation of food into energy we can use.
Hormones, like thyroxin and triiodothyronine, influence blood pressure, heart rate, body temperature and weight. The basal metabolic rate is maintained by the body with the help of these hormones, which also plays a role in protein synthesis. (20)
2. Maintains Optimal Energy Levels
Iodine plays a vital role in maintaining optimal energy levels of the body by the utilization of calories, without allowing them to be deposited as excess fat.
3. Helps Prevent Certain Kinds of Cancer
Iodine plays a role in boosting immunity and inducing apoptosis, the self-destruction of dangerous, cancerous cells. While iodine assists in destroying mutated cells, it doesn’t destroy healthy cells in the process. Evidence shows the ability of iodine-rich seaweed to inhibit growth of breast tumor development. (21) This is supported by the low rate of breast cancer in parts of world, especially in Japan, where women consume a diet rich in iodine. If you notice breast changes in your breast tissue, it could be a sign of iodine deficiency.
Bromine plays a role here as well, as research shows bromine is a suspected carcinogen that “may exacerbate iodine insufficiency since bromine competes for iodine uptake by the thyroid gland and other tissues (i.e. breast).” (22)
4. Removes Toxic Chemicals
Iodine can remove heavy metal toxins like lead, mercury and other biological toxins. Accumulating evidence suggests there are many extrathyroidal benefits of iodine, including antioxidant functions, maintaining the integrity of the mammary gland as well as antibacterial properties, particularly against H. pylori, which is a bacterial infection in the stomach and associated with gastric cancer. (23)
5. Boosts Immunity
Iodine doesn’t just affect the thyroid; it does many other things, including playing an important role as an immune booster. Iodine is a scavenger of free hydroxyl radicals and stimulates and increases the activity of antioxidants throughout the body to provide a strong defensive measure against various diseases, including cancer and cardiovascular disease.
Recent studies have shown that iodine directly protects the brain cells of rats from the harmful effects of free radicals by bonding onto fatty acids in the cell membrane, leaving less room for free radicals to have a negative impact on the organism. (24)
6. Forms Healthy and Shiny Skin
Dry, irritated and rough skin that becomes flaky and inflamed is a common sign of iodine deficiency. Iodine helps with the formation of shiny and healthy skin, hair and teeth and is an important trace element, as a lack of iodine results in hair loss.
A clinical study performed in Mexico wanted to determine the trace elements of healthy hair in malnourished children. Iodine levels were 10-fold higher than what has been reported by other authors. (25)
7. Prevents Enlarged Thyroid Gland
Iodine deficiency is widely recognized as the primary cause of goiter. In fact, according to a meta-analysis out of China, lower urinary iodine concentration values “were associated with an increased risk of goiter, and … iodine deficiency may lead to an increased risk of goiter.” (26)
Add sea salt, seafood, raw milk and eggs to your diet to avoid iodine deficiency, as this often also works as a preventative step of an enlarged thyroid gland.
8. Helps Prevent Impaired Development and Growth in Children
Studies have shown that iodine deficiency during infancy and pregnancy can interrupt healthy brain development and growth. Infants are more susceptible to mortality and high risk for neurodegenerative problems if iodine-deficient, such as a mental form of disability known as cretinism, motor function problems, learning disabilities and low growth rate.
In fact, according to research published by professors at the University of Sydney in Australia and the Swiss Federal Institute of Technology in Sweden, “Brain damage and irreversible mental retardation are the most important disorders induced by iodine deficiency.” (27)
It’s difficult to get an accurate reading of iodine levels, even though doctors commonly test women for iodine deficiency during pregnancy. It’s encouraged by health care professionals for women to increase their supplementation with iodine and intake of iodine-rich foods to prevent these deficiencies.
Increasing Intake of Iodine Naturally
To increase intake of iodine, try adding foods that are naturally high in iodine into your diet through the following recipes:
- Traditional egg salad recipe
- Adding seaweed to or other sea vegetables to miso soup
- Try making a savory baked fish dish
- Whip up some cranberry sauce with pecans
- Enjoy a morning yogurt berry smoothie
Potential Side Effects
Iodine overdose of more than 2,000 milligrams could be dangerous, especially in individuals who are diagnosed with tuberculosis or kidney disease. Iodine in excess could result in thyroid papillary cancer and hyperthyroidism rather than prevention. Pregnant women and nursing mothers should be cautious not to take iodine except in specifically prescribed doses.
A healthy balance is required, but different people’s bodies will react differently to dose amounts. People who have Hashimoto’s, thyroiditis or particular cases of hypothyroid individuals should speak with their doctors to discuss how much, if any, iodine should be taken through careful supplementation. (28)
- Iodine is a trace mineral and an essential component of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). These hormones regulate the metabolic activities of most cells and play a vital role in the process of early growth and development of most organs, especially the brain.
- Inadequate intake of iodine-rich foods leads to insufficient production of these hormones, which adversely affect the muscle, heart, liver, kidney and the developing brain.
- Symptoms of iodine deficiency include depression, difficulty losing weight, dry skin, headaches, lethargy or fatigue, memory problems, menstrual problems, hyperlipidemia, recurrent infections, sensitivity to cold, cold hands and feet, brain fog, thinning hair, constipation, shortness of breath, impaired kidney function, muscle weakness, and joint stiffness.
- Risk factors for iodine deficiency include low dietary iodine, selenium deficiency, pregnancy, tobacco smoke, fluoridated and chlorinated water, and goitrogen foods.
- The RDA for iodine is 150 micrograms a day for adults and teens over 14 years old, and pregnant or breastfeeding mothers should consume 290 micrograms every day.
- Iodine benefits the body by helping control metabolic rate, maintain optimal energy, prevent certain kinds of cancer, remove toxins, boost immunity, form healthy and shiny skin, prevent an enlarged thyroid, and prevent impaired development and growth in children.