🧂 Iodine: Organic (Kelp) vs Inorganic (Potassium Iodide, Lugol's)
Which iodine form to choose and why dosage matters
Iodine is a trace element needed for the synthesis of thyroid hormones. In supplements it appears in organic (kelp) and inorganic (potassium iodide, Lugol's) forms. We break down their differences.
What is iodine
Iodine is a trace element that the body does not synthesise and gets from food. It is a building block for thyroid hormones T4 and T3, which regulate metabolism.
- Not synthesised by the body.
- Building block for T4/T3.
- Regulates metabolism.
- Only from food.
Thyroid gland
The thyroid gland uses iodine to produce hormones. Iodine deficiency leads to gland enlargement (goitre) and metabolic disorders. Excess iodine is also dangerous.
- Iodine needed for T4/T3.
- Deficiency — goitre.
- Metabolic disorders.
- Excess also dangerous.
Kelp (organic iodine)
Kelp is a brown seaweed, a source of organic iodine. It contains iodine in a natural matrix along with other minerals. The iodine concentration in kelp can vary greatly.
- Organic iodine from seaweed.
- Natural matrix with minerals.
- Concentration varies.
- Popular in supplements.
Potassium iodide
Potassium iodide is an inorganic iodine form, standardised and precisely dosed. Used in iodised salt and supplements. Usually preferred for precise dose control.
- Inorganic form.
- Standardised dose.
- In iodised salt.
- Precise dose control.
Lugol's
Lugol's solution is a concentrated inorganic iodine form (iodine + potassium iodide). Used in medicine, but oral use requires great caution due to the high dose.
- Concentrated iodine solution.
- Medical use.
- High dose.
- Caution with oral use.
Food: sources
| Food | Iodine content | Comment |
|---|---|---|
| Seaweed (kelp) | ~200–300 mcg/100 g | Very concentrated |
| Cod | ~100 mcg/100 g | Fish |
| Shrimp | ~40 mcg/100 g | Seafood |
| Milk | ~30–50 mcg/L | Dairy |
| Iodised salt | ~40 mcg/g | In 1/2 tsp ~150 mcg |
How much to eat
- Norm 150 mcg/day: ~100 g of cod or 1/2 tsp of iodised salt.
- Seaweed: a small portion — easily exceeds the norm.
- Be careful with seaweed due to high concentration.
Norms
| Indicator | Value | Comment |
|---|---|---|
| Daily norm | 150 mcg | Adults |
| Pregnancy | 220 mcg | Higher norm |
| Lactation | 290 mcg | Higher norm |
| Upper limit | 1100 mcg | From supplements |
What is iodine?
A trace element needed for thyroid hormones.
How does kelp differ from potassium iodide?
Kelp is organic iodine from seaweed; potassium iodide is inorganic with a precise dose.
How much iodine a day?
150 mcg adults, 220 mcg pregnant, 290 mcg lactating.
Is Lugol's safe?
Lugol's is concentrated — oral use only on a doctor's advice.
Which iodine form to choose?
Potassium iodide gives a precise dose; kelp is organic but variable.
Where is a lot of iodine?
Seaweed, cod, shrimp, iodised salt.
Is excess iodine dangerous?
Yes, excess can cause hyperthyroidism and thyroiditis.
How much iodine in seaweed?
~200–300 mcg/100 g — easily exceeds the norm.
Are tests needed before iodine?
It is advisable to check thyroid function.
Who should not take iodine?
With hyperthyroidism and some thyroid diseases — with a doctor.