Iodine
Definition
What 'Iodine' means
Iodine is primarily obtained from iodized salt, seafood, and dairy products. The thyroid gland uses iodine to synthesize thyroxine and triiodothyronine, hormones that control metabolic rate and fetal development. Deficiency can cause goiter, hypothyroidism, and cognitive impairment. Plant-based diets may be low in iodine unless seaweed or iodized salt is consumed.
Related terms
In depth
The longer answer
Iodine is an essential trace mineral that the human body requires for the production of thyroid hormones, which regulate metabolism, growth, and development. In the context of a plant-based diet, you encounter iodine primarily through fortified foods, sea vegetables, and iodized salt. Many people assume that a varied whole-food plant-based diet naturally provides enough iodine, but this is not always the case, as soil content varies and most plant foods are low in iodine unless fortified.
In practice, the primary dietary sources of iodine for most people are iodized table salt, dairy products (due to iodine-containing disinfectants used in milking), and seafood. For those avoiding animal products, iodized salt remains the most reliable and consistent source, with about half a teaspoon providing the daily recommended intake. Sea vegetables like kelp, nori, and wakame contain highly variable amounts of iodine, ranging from moderate to extremely high levels, making them an inconsistent source that can lead to excessive intake if consumed frequently.
For someone eating a plant-based diet, iodine status matters because both deficiency and excess can disrupt thyroid function, leading to fatigue, weight changes, or goiter. A practical approach is to use iodized salt in cooking or at the table, or to take a modest supplement of 150 micrograms daily. The nuance is that many sea salt and gourmet salts are not iodized, and relying on seaweed can be risky due to unpredictable iodine content, so conscious inclusion of a reliable source is necessary.
At a glance
Quick facts
| Detail | What to know |
|---|---|
| Daily requirement | 150 micrograms for most adults |
| Common sources | Iodized salt, seaweed, dairy, eggs |
| Deficiency risk | Higher in plant-based diets without iodized salt |
| Excess risk | Possible with frequent high-seaweed intake |
In practice
What this means for you
- Check your salt container: if it says "iodized" or "with iodine," half a teaspoon daily meets your needs.
- If you avoid added salt, consider a 150 mcg iodine supplement, as plant foods alone rarely provide enough.
- When using seaweed like kelp, limit to once weekly and avoid supplements with high iodine doses.
- Ask your healthcare provider to check your iodine status if you feel fatigued or have unexplained weight changes.
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