Global Iodine Intake: A Look at Different Countries' Dietary Patterns

Iodine intake varies dramatically by country and diet, largely due to soil iodine content and food traditions. This post compares dietary patterns across several regions and what drives the differences.

Why Iodine Intake Varies So Much

Iodine is unevenly distributed across the planet. Most of it sits in the oceans, and it reaches land through rain and sea spray. Areas near the coast tend to have more iodine in their soil, while mountainous and inland regions, especially those once covered by glaciers or prone to flooding, tend to have less. Crops and livestock in low-iodine regions carry less iodine into the food supply. On top of geography, two human factors shape intake: food traditions and public health policy.

A Look at Different Regions

• Japan and Korea: traditional diets include seaweed such as kombu, wakame and nori, along with plenty of seafood. Average iodine intake there is among the highest in the world.
• United States: no natural iodine advantage, but voluntary iodized salt since 1924, iodine in dairy and a varied diet have kept average intake broadly adequate. See A Short History of Iodized Salt in the U.S.
• United Kingdom: the UK has no mandatory salt iodization, and milk has long been the main iodine source. Research has raised questions about intake in groups that drink less milk.
• Switzerland: an Alpine country with naturally low-iodine soil, Switzerland was one of the first countries to introduce iodized salt, in 1922, and it adjusts the level over time.
• Mountain regions worldwide: parts of the Himalayas, the Andes and Central Africa historically had very low iodine intake before fortification programs reached them.

The Role of Fortification

Today, policy often matters more than geography. Since the 1990s, the World Health Organization and UNICEF have promoted universal salt iodization, and most countries now have salt iodization programs. That effort has sharply reduced the number of countries with population-wide iodine shortfalls. Read more in How Fortification Programs Actually Work and Iodine Deficiency Disorders: A Global Public Health History.

How Intake Is Measured

Because the body excretes most of the iodine it takes in through urine, researchers measure population iodine status by testing urinary iodine across a large sample of people. A single person's result varies a lot from day to day, so this method works for describing populations rather than individuals.

What It Means for an Individual

National averages don't tell any one person what they're getting. Someone in a well-supplied country can still have low intake if they avoid dairy, eggs, seafood and iodized salt, and someone who eats a lot of seaweed may take in far more than average. Looking at your own diet is the most useful starting point. Our daily iodine intake guide explains how much is recommended and where it comes from.

Frequently Asked Questions

Can I get enough of this nutrient from food alone?
Diet is the primary source for most nutrients, iodine included, and dietary sources vary widely by region and food choices. A healthcare provider or registered dietitian is the right resource for questions about your specific intake.

How do I know if my own intake is on the lower end?
See our complete guide to iodine deficiency for signs, causes, and how it's assessed.

Shop Lugol's Solution — the traditional, trusted way people have supported their iodine intake for over 200 years.

Lauren Mitchell covers comparisons, formats, and quality questions for the Iodine Journal.

This article is for general educational purposes only and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease, and is not a substitute for advice from a qualified healthcare provider — especially if you are pregnant, nursing, taking thyroid medication, or managing a thyroid condition.