The Silent Loss: How Modern Food Production is Stripping Iodine from Our Diets

Most people assume that if they eat a balanced diet, they will get all the nutrients their body needs. But when it comes to iodine, this assumption is increasingly untrue. Modern agricultural and food production practices have quietly reduced the iodine content of our diets, leaving many people unknowingly deficient.

Why Iodine is Essential

Iodine is a trace mineral that the body cannot make on its own. It is required for the production of thyroid hormones, which regulate metabolism, growth, and brain development. Without sufficient iodine, thyroid function falters—leading to fatigue, weight gain, poor concentration, and in severe cases, goiter. For pregnant women, deficiency can impair fetal brain development and lower cognitive outcomes in children (1).

The Shrinking Iodine Content in Foods

Historically, iodine came into the diet through natural sources such as iodine-rich soils, seafood, and dairy. But over the past 50 years, these sources have become less reliable:

• Soil depletion: Many North American soils are naturally low in iodine. Intensive farming practices further strip minerals from the soil, leaving crops with minimal iodine content.

• Changes in animal feed: Dairy used to be a dependable iodine source because livestock feed was supplemented. Today, different feed formulations and changes in sanitization practices for dairy equipment have reduced iodine levels in milk and dairy products.

• Processed foods: Although they are high in salt, most processed foods do not use iodized salt, removing one of the main public health protections against deficiency.

• Shift in salt habits: Public health campaigns to reduce salt intake, along with the popularity of natural salts like sea salt and Himalayan pink salt (which typically contain little to no iodine), have further reduced iodine exposure.

The Health Consequences

The consequences of this decline are not theoretical—they are showing up in public health surveys. Urinary iodine levels, the best marker of iodine intake, have declined in the North American population, particularly among women of reproductive age.

Low iodine intake contributes to:

• Thyroid dysfunction: Hypothyroidism, fatigue, weight gain, and impaired metabolism.

• Pregnancy risks: Increased risk of miscarriage, stillbirth, and reduced cognitive outcomes for the child.

• Child development issues: Even mild deficiency during pregnancy can reduce IQ and school performance in children.

• Immune and skin barrier weakness: Iodine plays a role in skin and mucosal defense, meaning deficiency can increase susceptibility to infections (2).

The Way Forward

The return of iodine deficiency is a public health problem hiding in plain sight. Solutions are within reach:

• Use iodized salt in home cooking, even if reducing overall sodium intake.

• Include iodine-rich foods such as seafood, seaweed, eggs, and dairy.

• For those at higher risk—pregnant women, vegetarians, or individuals who avoid dairy and seafood—consider iodine supplementation under healthcare guidance.

Final Thoughts

The gradual disappearance of iodine from our foods is a reminder that nutrition is not only about what we eat, but also about how our food is produced. Without awareness and action, a mineral once thought to be a problem of the past may again shape the health of future generations.

Written by: Dr Evan Lewis

References:

1. Zimmermann MB, Boelaert K. Iodine deficiency and thyroid disorders. Lancet Diabetes Endocrinol. 2015;3(4):286–295.

2. Leung AM, Pearce EN, Braverman LE. Iodine nutrition in North America: Trends and public health implications. Thyroid. 2011;21(5):519–528.