There’s a good chance you’ll spot a box of iodized salt in any kitchen pantry.
While it’s a dietary staple in many households, there’s a lot of confusion about what iodized salt actually is and whether or not it’s a necessary part of the diet.
This article explores how iodized salt may affect your health and whether or not you should be using it.
Iodine is a trace mineral commonly found in seafood, dairy products, grains and eggs.
In many countries, it’s also combined with table salt to help prevent iodine deficiency.
Thyroid hormones also play a direct role in the control of body temperature, blood pressure and heart rate (3).
In addition to its essential role in thyroid health, iodine may play a central role in several other aspects of your health.
Summary Your thyroid gland uses iodine to produce thyroid hormones, which play a role in tissue repair, metabolism and growth and development. Iodine may also impact immune health and help treat fibrocystic breast disease.
Unfortunately, many people around the world are at an increased risk of iodine deficiency.
It's considered a public health problem in 118 countries, and more than 1.5 billion people are believed to be at risk (8).
Deficiencies in micronutrients like iodine are increasingly prevalent in certain areas, especially in regions where iodized salt is uncommon or there are low levels of iodine in the soil.
In fact, it’s estimated that about a third of the population in the Middle East is at risk of iodine deficiency (9).
This condition is also commonly found in areas such as Africa, Asia, Latin America and parts of Europe (8).
In addition, certain groups of people are more likely to be deficient in iodine. For example, women who are pregnant or breastfeeding are at a higher risk of deficiency because they require more iodine.
Vegans and vegetarians are also at a greater risk. One study looked at the diets of 81 adults and found that 25% of vegetarians and 80% of vegans had iodine deficiency, compared to just 9% of those on mixed diets (10).
Summary Iodine deficiency is a major problem around the world. Women who are pregnant or breastfeeding, those on a vegan or vegetarian diet and those who live in certain areas of the world are at a greater risk of deficiency.
A deficiency in iodine can cause a long list of symptoms that range from mildly uncomfortable to severe to even dangerous.
Among the most common symptoms is a type of swelling in the neck known as a goiter.
Your thyroid gland uses iodine to produce thyroid hormones. However, when your body doesn’t have enough of it, your thyroid gland is forced to go into overdrive to try to compensate and make more hormones.
This causes the cells in your thyroid to rapidly multiply and grow, resulting in a goiter (11).
A decrease in thyroid hormones can also lead to other adverse effects, such as hair loss, fatigue, weight gain, dry skin and increased sensitivity to cold (12).
Iodine deficiency may cause serious issues in children and pregnant women as well. Low levels of iodine can cause brain damage and severe problems with mental development in children (8).
What’s more, it may also be associated with a higher risk of miscarriages and stillbirth (13).
Summary Iodine deficiency can impair the production of thyroid hormones, resulting in symptoms like swelling in the neck, fatigue and weight gain. It may also cause problems in children and pregnant women.
In 1917, physician David Marine began conducting experiments demonstrating that taking iodine supplements was effective at reducing the incidence of goiters.
Soon after in 1920, many countries around the globe began fortifying table salt with iodine in an effort to prevent iodine deficiency.
The introduction of iodized salt was incredibly effective at eliminating the deficiency in many parts of the world. Prior to the 1920s, up to 70% of children in certain areas of the United States had goiters.
In contrast, today 90% of the US population has access to iodized salt, and the population is considered overall iodine sufficient (14).
Just a half teaspoon (3 grams) of iodized salt per day is enough to meet your daily iodine requirement (15).
This makes using iodized salt one of the easiest ways to prevent iodine deficiency without having to make other major modifications to your diet.
Summary In the 1920s, health authorities began adding iodine to table salt in an effort to prevent iodine deficiency. Just a half teaspoon (3 grams) of iodized salt can meet your daily needs for this mineral.
Studies show that iodine intake above the daily recommended value is generally well tolerated.
In fact, the upper limit of iodine is 1,100 micrograms, which is the equivalent to 6 teaspoons (24 grams) of iodized salt when each teaspoon contains 4 grams of salt (15).
However, excessive intake of salt, iodized or not, is not advised. The World Health Organization (WHO) recommends less than 5 grams of salt per day for adults (16).
Therefore, you will exceed the safe level of salt intake long before you exceed your daily recommended dose of iodine.
A high intake of iodine may increase the risk of thyroid dysfunction in certain groups of people, including fetuses, newborn babies, the elderly and those with preexisting thyroid disease.
Excess iodine intake can be a result of dietary sources, iodine-containing vitamins and medications and taking iodine supplements (17).
That said, multiple studies have reported that iodized salt is safe with minimal risk of adverse side effects for the general population, even at doses nearly seven times the daily recommended value (18, 19, 20).
Summary Studies show iodized salt is safe to consume with minimal risk of side effects. The safe upper limit of iodine is nearly 4 teaspoons (23 grams) of iodized salt per day. Certain populations should take care to moderate their intake.
Although iodized salt is a convenient and easy way to up your intake of iodine, it’s not the only source of it.
In fact, it’s entirely possible to meet your iodine needs without consuming iodized salt.
Other good sources include seafood, dairy products, grains and eggs.
Here are a few examples of foods that are rich in iodine:
- Seaweed: 1 sheet dried contains 11–1,989% of the RDI
- Cod: 3 ounces (85 grams) contains 66% of the RDI
- Yogurt: 1 cup (245 grams) contains 50% of the RDI
- Milk: 1 cup (237 ml) contains 37% of the RDI
- Shrimp: 3 ounces (85 grams) contains 23% of the RDI
- Macaroni: 1 cup (200 grams) boiled contains 18% of the RDI
- Egg: 1 large egg contains 16% of the RDI
- Canned tuna: 3 ounces (85 grams) contains 11% of the RDI
- Dried prunes: 5 prunes contain 9% of the RDI
It’s recommended that adults get at least 150 micrograms of iodine per day. For women who are pregnant or breastfeeding, that number jumps to 220 and 290 micrograms per day, respectively (15).
By consuming just a few servings of iodine-rich foods each day, you can easily get enough iodine through your diet, with or without the use of iodized salt.
Summary Iodine is also found in seafood, dairy products, grains and eggs. Eating a few servings of iodine-rich foods per day can help you meet your needs, even without iodized salt.
If you’re consuming a balanced diet that includes other sources of iodine, such as seafood or dairy products, you’re probably getting enough iodine in your diet through food sources alone.
However, if you believe you are at a higher risk of iodine deficiency, you may want to consider using iodized salt.
Additionally, if you’re not getting at least a few servings of iodine-rich foods each day, iodized salt can be a simple solution to make sure you’re meeting your daily needs.
Consider using it in combination with a nutritious, varied diet to ensure you’re meeting your needs for iodine and other important nutrients.