Iodine
Iodine supports thyroid hormone production and growth. Food-first intake is preferred; supplements should be matched to diet, health context, and safety considerations.
Overview
Biological role
Iodine supports thyroid hormone production and growth.
Mechanism of action
Iodine contributes to normal physiology through nutrient-specific enzyme, structural, signaling, transport, or regulatory roles described in authoritative nutrition references.
Chemical forms
Iodine may appear in foods and supplements in different chemical forms. Selection should consider the nutrient form, dose, tolerance, and health context.
Quick answers before choosing a supplement
Chemical forms and absorption
Common forms
Iodine may appear in foods and supplements in different chemical forms. Selection should consider the nutrient form, dose, tolerance, and health context.
Absorption context
Absorption can vary with food composition, supplement form, dose, and timing. Food-first intake is preferred when possible.
Clinical use
Established essential nutrient roles should be separated from supplement benefit claims. Supplement use is most appropriate when there is inadequate intake, increased need, deficiency risk, or a clinical indication.
Absorption and action pathway
What to take with, and what to avoid
Works Well With
Avoid / Use Caution
Best time to take
Frequently asked questions
When is the best time to take Iodine?
Use with meals if the supplement irritates the stomach; separate from medicines or competing minerals when needed.
Can Iodine be taken with coffee or milk?
Some minerals compete with foods, drinks, or medicines. Separate timing is useful when treating a deficiency.
Who should be careful with Iodine?
Pregnant or lactating people, older adults, children, people with chronic diseases, and people taking regular medicines should use supplements with professional guidance.
Food and Intake
| Age / group | Male | Female | Pregnancy | Lactation | Upper limit |
|---|---|---|---|---|---|
| 1-3 years | 90 | 90 | – | – | UL 200 |
| 4-8 years | 90 | 90 | – | – | UL 300 |
| 9-13 years | 120 | 120 | – | – | UL 600 |
| 14-18 years | 150 | 150 | 220 | 290 | UL 900 |
| 19+ years | 150 | 150 | 220 | 290 | UL 1,100 |
International reference intake comparison
| Country / authority | Common reference value |
|---|---|
| USA / NIH-FNB | RDA 150 mcg; pregnancy 220; lactation 290; UL 1,100 |
| Europe / EFSA | AI/PRI adults 150 mcg; pregnancy/lactation 200 |
| Australia-New Zealand / NRV | RDI 150 mcg; pregnancy 220; lactation 270 |
| Thailand / Thai FDA | Thailand: use Thai RDI and Thai FDA / Ministry of Public Health regulations for labeling and supplement products. Do not interpret labeling values as therapeutic doses; product-specific limits must be checked against the latest notification and formula. |
This table compares reference-intake frameworks across authorities. Values may use different terms such as RDA, AI, PRI, or NRV and should not be merged into one universal dose.
Food source comparison for Iodine
| Food | Serving amount | Iodine | %DV | %DV bar | Servings to reach 150 mcg |
|---|---|---|---|---|---|
| cod | 3 oz | 158 mcg | 105% | 0.9 | |
| iodized salt | 1/4 teaspoon | 76 mcg | 51% | 2.0 | |
| yogurt | 1 cup | 75 mcg | 50% | 2 | |
| milk | 1 cup | 56 mcg | 37% | 3 | |
| egg | 1 egg | 24 mcg | 16% | 6 | |
| tuna | 3 oz | 17 mcg | 11% | 9 |
Food values are practical comparison values. Actual content varies by variety, preparation, fortification, and serving size.
Safety
Deficiency
Inadequate Iodine intake or absorption may affect body systems related to thyroid hormone production and growth. Deficiency risk depends on diet, absorption, medical conditions, and life stage.
Excess and toxicity
Too little or too much iodine can affect thyroid function.
Precautions
Too little or too much iodine can affect thyroid function.
Special populations
Pregnant or lactating people, older adults, children, people with chronic diseases, and people taking regular medicines should use supplements with professional guidance.
Fast risk map
LOW: insufficient intake
Inadequate Iodine intake or absorption may affect body systems related to thyroid hormone production and growth. Deficiency risk depends on diet, absorption, medical conditions, and life stage.
UL: excess intake
Too little or too much iodine can affect thyroid function.
Precautions: interactions and timing
Too little or too much iodine can affect thyroid function.
SP: special populations
Pregnant or lactating people, older adults, children, people with chronic diseases, and people taking regular medicines should use supplements with professional guidance.
Interactions and Clinical Context
Drug interactions
Potential interactions depend on the nutrient, supplement dose, medicines used, and medical conditions. People using regular medicines should check interaction guidance from clinical sources or ask a clinician.
Food interactions
Absorption can vary with food composition, supplement form, dose, and timing. Food-first intake is preferred when possible.
Clinical notes
Established essential nutrient roles should be separated from supplement benefit claims. Supplement use is most appropriate when there is inadequate intake, increased need, deficiency risk, or a clinical indication.
Evidence level
High for essential nutrient role; nutrient-specific supplementation benefits depend on baseline status and clinical context.