Why was iodine originally put in salt?

January 13, 2026 •

4 min read

Endemic goiter was so prevalent in the early 20th century in certain regions, like the American Midwest's 'goiter belt', that it became a major public health concern. This widespread issue was the primary catalyst for the practice of adding iodine to salt, a simple yet groundbreaking solution to a devastating deficiency.

Quick Summary

Iodine was first added to salt to eradicate widespread deficiencies that caused serious health problems, including goiter and intellectual disabilities. This cost-effective public health measure delivered a vital nutrient to large populations, especially those living far from iodine-rich coastal areas, to prevent severe developmental and metabolic disorders.

Key Points

Goiter Prevention: Iodine was added to salt to prevent goiter, a visible enlargement of the thyroid gland caused by iodine deficiency.
Cognitive Development: Fortification was a crucial measure to protect against intellectual disabilities and cretinism, especially affecting infants and children born to iodine-deficient mothers.
Public Health Initiative: The program began in regions known as 'goiter belts' (like the American Midwest), where iodine was naturally scarce in the soil and food supply.
A Cost-Effective Solution: Salt was chosen as the delivery vehicle because it is consumed consistently by nearly everyone, making mass fortification a cheap and highly effective public health strategy.
Early Adoption: Switzerland first introduced iodized salt in 1922, with the United States following suit in 1924, leading to a dramatic drop in goiter cases.
Ongoing Importance: Despite its historical success, public health officials continue to advocate for iodized salt due to changing dietary habits, which can lead to insufficient iodine intake.

A Silent Epidemic: The Iodine Deficiency Crisis

For centuries, people in certain inland regions around the world suffered from endemic goiter, a visible and often disfiguring enlargement of the thyroid gland. This condition was a clear symptom of a deeper, more severe problem: chronic iodine deficiency. Iodine is an essential micronutrient the body cannot produce on its own and requires for the thyroid gland to create critical hormones that regulate metabolism, growth, and development. Without enough iodine, the thyroid works overtime to absorb more of the scarce mineral, causing it to swell. But the consequences were far more devastating than just a swollen neck; severe deficiency during pregnancy could cause miscarriages, stillbirths, and cretinism—a condition leading to severe, irreversible mental and physical disabilities in infants. The intellectual and developmental impairment caused by iodine deficiency was, and still is, recognized as the leading preventable cause of brain damage worldwide.

The Birth of a Public Health Solution

In the early 1900s, driven by mounting evidence, scientists and health officials began actively seeking a solution. Notable figures like Dr. David Marine, an American pathologist, conducted landmark trials on schoolgirls in Akron, Ohio, between 1917 and 1922. His experiments conclusively demonstrated that administering small doses of iodine could dramatically reduce the incidence of goiter. This evidence paved the way for a public health revolution. The challenge became finding an effective, cheap, and universally consumed vehicle to deliver this vital nutrient.

Salt proved to be the perfect candidate for fortification. It is a staple ingredient that does not spoil and is consumed in relatively consistent amounts by nearly everyone.

The History of Iodized Salt

The first nationwide salt iodization program was pioneered in Switzerland in 1922, targeting areas with a high prevalence of goiter. The success of the Swiss program inspired similar efforts in the United States. In 1924, following advocacy from physicians like Dr. David Cowie from the University of Michigan, iodized salt became commercially available in Michigan, part of the country's severe 'goiter belt'. The Morton Salt Company soon began national distribution, and the results were stunning; the prevalence of goiter plummeted. This relatively simple step led to significant improvements in public health, including increased average IQ scores in formerly iodine-deficient areas.

Benefits of Iodized Salt vs. Dangers of Deficiency

The public health impact of iodized salt is clear when comparing its benefits to the devastating effects of iodine deficiency:


Aspect	Iodized Salt Benefits	Iodine Deficiency Consequences
Thyroid Health	Supports proper thyroid function, preventing goiter.	Causes enlargement of the thyroid gland (goiter) and hypothyroidism.
Neurological Development	Essential for healthy brain development in fetuses and young children.	Impairs cognitive function, leading to developmental disabilities and lower IQs.
Reproductive Health	Reduces risks of miscarriage and stillbirth in pregnant women.	Increases risk of miscarriage, stillbirth, and infertility.
Metabolism	Supports healthy metabolism, energy levels, and body temperature regulation.	Results in fatigue, sensitivity to cold, and weight gain due to slowed metabolism.
Prevention Strategy	A cost-effective, passive strategy requiring no dietary habit changes.	Leads to a spectrum of disorders affecting millions globally.

Modern Iodine Concerns

Despite the remarkable success of salt iodization, iodine deficiency remains a concern in some populations today. For instance, the rise in non-iodized specialty salts (like sea salt or Himalayan pink salt), the use of non-iodized salt in processed foods, and campaigns to reduce overall salt intake can lead to lower iodine consumption. Many health experts now recommend that pregnant and breastfeeding women take a supplement to ensure they meet their higher iodine needs. Global efforts continue to ensure universal salt iodization (USI), especially in developing nations where deficiency is still a major issue. The World Health Organization (WHO) identifies iodization as one of the most cost-effective measures to improve public health globally.

The Ongoing Legacy of Fortification

The story of adding iodine to salt is a powerful testament to the effectiveness of simple public health interventions. What began as a solution to endemic goiter in specific regions has evolved into a global strategy to prevent a spectrum of disorders that can hinder both individual potential and national development. This measure showcases how small, consistent changes to food production can have a monumental impact on human well-being. By fortifying a common household item, public health pioneers were able to effectively end a widespread and crippling epidemic. It’s a remarkable story of science, collaboration, and common sense leading to a healthier population. For further information on the global impact of iodine programs, you can read more from the National Institutes of Health.

Conclusion: More Than Just a Mineral

Iodine was originally put in salt to address a severe public health crisis caused by widespread iodine deficiency. This simple, cost-effective intervention successfully prevented endemic goiter and more devastating conditions like cretinism, improving neurological development and overall health for millions. While the initial crisis has largely been resolved in many countries, maintaining adequate iodine intake remains important due to evolving dietary habits and global food systems. The legacy of iodized salt continues to underscore the vital role of micronutrient fortification in protecting public health on a mass scale.

Frequently Asked Questions

Goiter is the abnormal enlargement of the thyroid gland, which is located at the front of the neck. The most common cause worldwide is iodine deficiency, forcing the thyroid to enlarge in an attempt to absorb more iodine.

No, not all salt contains iodine. While most table salt is iodized, specialty salts like sea salt, kosher salt, and Himalayan pink salt are often not fortified. It is important to check the label if you rely on salt for your iodine intake.

Symptoms of iodine deficiency can include goiter, fatigue, weight gain, increased sensitivity to cold, and dry skin. During pregnancy, it can have more severe consequences for both the mother and the developing fetus.

Yes, other excellent sources of iodine include seafood (fish and seaweed), dairy products, and eggs. However, in many landlocked areas, the iodine content in local produce is low due to insufficient iodine in the soil.

People who live far from coastal areas and rely on food grown in iodine-poor soil are historically at risk. Today, at-risk groups also include pregnant and breastfeeding women, and those who avoid dairy and seafood or opt for non-iodized salts.

Yes, excessive iodine intake can also cause thyroid problems. This can be a concern in fortification programs if not properly monitored. For most healthy adults, consuming iodized salt as part of a balanced diet does not pose a risk.

Cretinism is a historical term for a severe, irreversible form of mental and physical disability caused by severe iodine deficiency during fetal development. Widespread salt iodization programs have largely eradicated this condition in many parts of the world.