Iodine. You probably don’t think about it much, but this tiny mineral plays a huge role in your health. As a doctor, I’ve seen firsthand how iodine deficiency can lead to serious problems like hypothyroidism, goiter, and pregnancy complications.
That’s why I’m a big believer in iodized salt. But lately, I’ve noticed a lot of misinformation and confusion about this simple but powerful health intervention. Patients come to me with questions like,
“Is iodized salt really necessary?”
“Can’t I just use sea salt instead?”
“How much iodine do I need?”
If you’ve ever wondered about the importance of iodine in your diet, you’re not alone. In this post, I’ll clear up some common misconceptions and share what the science says about iodine, iodized salt, and your health.
What is Iodine and Why Do We Need It?
Iodine is a trace mineral that’s essential for proper thyroid function. The thyroid gland needs iodine to produce thyroid hormones, which regulate metabolism, growth, brain development, and other vital functions in the body.
Without enough iodine, the thyroid can’t produce adequate amounts of these critical hormones. Iodine deficiency is a leading cause of hypothyroidism (underactive thyroid). It can also cause goiter (enlargement of the thyroid gland), pregnancy complications, and impaired cognitive development in children.
Why Was Iodine Added to Salt?
Iodine deficiency used to be common worldwide, especially in mountainous inland areas with iodine-poor soil. In 1924, iodized table salt was first sold in the U.S. to help prevent iodine deficiency. Many other countries, including India, later began fortifying salt with iodine as well.
Adding iodine to salt has been incredibly effective at reducing iodine deficiency globally. However, some of my patients, like Radhe, the urban farmer, ask me “Why do we need iodized salt now when people lived without it for thousands of years?”
It’s a fair question. The truth is, iodine deficiency was a problem then too – we just didn’t fully understand the consequences. Ancient Ayurvedic medical texts describe thyroid enlargement, likely due to iodine deficiency. Hippocrates wrote about goiter as an “enlargement of the neck” circa 460 BC.
What’s changed in modern times is that we now have the scientific knowledge and means to easily prevent iodine deficiency through salt fortification. Over the past century, iodizing salt has dramatically reduced thyroid disorders and improved public health outcomes.
How Much Iodine Do You Need?
The recommended daily allowance (RDA) for iodine varies by age
- Birth to 6 months: 110 mcg
- 7-12 months: 130 mcg
- 1-8 years: 90 mcg
- 9-13 years: 120 mcg
- 14+ years: 150 mcg
- Pregnancy: 220 mcg
- Breastfeeding: 290 mcg
Most people can get enough iodine from a half teaspoon of iodized salt per day. One teaspoon of iodized salt contains approximately 400 mcg of iodine. Iodine is also found naturally in seafood, dairy products, grains, and eggs. One large egg contains about 24 mcg of iodine.
Does Everyone Need Iodized Salt?
With few exceptions, I recommend iodized salt for just about everyone. Ramana asked me if iodine deficiency causes hypothyroidism or hyperthyroidism in his wife’s case. In most cases, lack of iodine leads to an underactive thyroid gland (hypothyroidism) and sometimes goiter. However, adding iodine to the diet of someone who’s been chronically deficient can occasionally trigger temporary hyperthyroidism.
I reassured Ramana that iodized salt is still very important for his wife. Hypothyroidism is more common in women, and proper iodine intake is especially critical for women who are pregnant or may become pregnant. Iodine deficiency in pregnancy can lead to miscarriage, stillbirth, preterm delivery, and impaired neurological development in the child.
What About Sea Salt and Rock Salt?
Some of my patients, like Triveni the food enthusiast, prefer using natural sea salt or rock salt. But unlike table salt, these salts are not typically fortified with iodine. While it’s true that soil and water near oceans tend to be higher in iodine, modern processing of sea salt often removes most of the naturally occurring iodine.
The iodine content of sea salt and rock salt is highly variable. One study found that the iodine levels in 12 brands of sea salt from different countries ranged from 0.17 ppm to 148.1 ppm. So while it’s possible to get some iodine from non-iodized salts, it’s difficult to know how much you’re really getting. Sticking with iodized salt is a more reliable way to meet your daily iodine needs.
Varun, a software engineer, asked me why coastal areas tend to have lower rates of goiter (the main symptom of severe iodine deficiency). This is because the soil and water near oceans generally have higher iodine levels, so people there often get more iodine in their diets even without iodized salt. However, due to modern changes like soil erosion and reduced intake of local foods, mild to moderate iodine deficiency can still occur in coastal populations lacking additional iodine sources.
Iodized Salt Best Practices
For maximum iodine retention, I advise my patients to store iodized salt in a cool, dark, dry place and to use it within 5 years. Iodine is sensitive to light, heat, moisture, and air exposure. While some iodine may be lost during cooking, iodized salt is still an effective way to boost your iodine intake. Consuming a variety of iodine-rich foods like seafood and dairy also helps.
The Bottom Line
Based on the research and my clinical experience, I believe iodized salt is an important part of a healthy diet for most people. Severe iodine deficiency is now rare in many places thanks to salt iodization programs, but mild to moderate insufficiency can still occur without adequate intake.
If you think you may be at risk for thyroid problems or iodine deficiency, talk to your doctor. A simple urine test can check your iodine levels. While it’s important not to get too much iodine, the greater danger for most people is getting too little. Used as recommended, iodized salt is a safe, smart choice to help maintain your thyroid and overall health.
