Iodine
Iodine has one primary job in the body and it’s a significant one: it’s essential for the production of thyroid hormones, which regulate metabolism, energy levels, body temperature, growth, and brain development. Without adequate iodine, the thyroid can’t produce those hormones properly. The result is a sluggish metabolism, persistent fatigue, and over time, an enlarged thyroid gland called a goiter as the body attempts to compensate by growing more thyroid tissue to capture whatever iodine is available.
Iodine deficiency was historically widespread and remains the leading preventable cause of intellectual disability globally, primarily because inadequate iodine during pregnancy significantly impairs fetal brain development. The introduction of iodized salt in the early twentieth century addressed this dramatically in many countries — it’s one of the more impactful public health interventions in nutritional history.
The practical concern today is that iodized salt is less prominent than it used to be. The shift toward sea salt, Himalayan pink salt, and artisanal salts — none of which are iodized — combined with reduced overall salt intake in health-conscious eaters, means iodine intake has quietly declined in some populations. Seafood and dairy are the other reliable sources. People eating a varied diet that includes seafood or dairy regularly are generally fine. People eating plant-based diets built around whole unprocessed foods and non-iodized salt are at real risk of inadequate iodine intake and should pay specific attention to this one.
Reference Card
Mineral type: Trace mineral Pillar: Nourish
What it does for you
- Essential for thyroid hormone production
- Thyroid hormones regulate metabolism, energy, body temperature, and growth
- Critical for brain development during pregnancy and infancy
Where to get it
- Iodized salt — the most reliable and consistent source for most people
- Seafood — cod, tuna, shrimp, seaweed
- Dairy — milk, yogurt, cheese
- Eggs
Considerations
- Switching from iodized salt to non-iodized alternatives like sea salt or Himalayan salt removes the most reliable iodine source from the diet without most people realizing it
- Plant-based eaters who don’t use iodized salt and don’t eat seafood or dairy are at meaningful risk of inadequate intake
- Seaweed is very high in iodine but inconsistently so — not a reliable daily source
- Iodine needs increase during pregnancy — worth specific attention for anyone who is pregnant or planning to become pregnant
Signs your intake might be low
- Persistent fatigue and sluggishness
- Feeling cold when others don’t
- Weight gain without clear cause
- Visible swelling at the base of the throat in more significant deficiency
Common myths
- Sea salt and Himalayan salt provide iodine — they contain only negligible trace amounts; they are not substitutes for iodized salt as an iodine source
- Iodine deficiency is a solved problem — iodized salt addressed it significantly but dietary trends toward non-iodized specialty salts and plant-based eating have created new pockets of inadequate intake