Iodine is an essential micronutrient present in very small amounts in our body. Iodine enters into the composition of the thyroid hormones produced by the thyroid gland. In fetuses and small children, thyroid hormones regulate the growth and development of most organs, especially the brain and cell differentiation. In people of all ages, they also stimulate metabolism and oxygen consumption by tissues.
What does iodine do?
Used externally, iodine has antiseptic and disinfecting properties and serves as a contrast material in radiology exams.
A normal diet generally provides all the iodine people need. The body gets the iodine it requires in the form of mineral salts called iodides, and iodide requirements depend on the accumulation and replenishment of iodine in the thyroid gland.
Recommended Dietary Allowance (RDA) for Iodine:
|Age||Amount (µg/Day) (RDA)|
|Infants||Birth to 6 months||110 (AI*)|
|7 to 12 months||130 (AI*)|
|Children||1 to 3 years||90|
|4 to 8 years||90|
|Preteens||9 to 13 years||120|
|Teens||Age 14 and older||150|
|Pregnant women|| ||220|
Source: DRI, Dietary Reference Intakes, 2006, p.320.
*(AI) = Adequate intake for those two age groups.
Most foods contain a small amount of iodine that varies with the iodine content of the soil they were harvested from and the type of irrigation and fertilizers used. Most foods have an iodine content of 3 to 75µg of iodine per portion. Some processed foods contain large amounts of iodine from the addition of iodized salt or additives, such as calcium or potassium iodate and potassium or copper iodide.
Note: The addition of iodine to table salt is mandatory in Canada. 76 mg of potassium iodide per kilogram of salt is used. Sea salt does not have to be iodine enriched. Make sure the sea salt you choose is.
Food Sources for Iodine:
|Foods||Portion size||(Iodine = µg)|
|Seafood (including seaweed)|| || |
|Iodized table salt||1 tsp||134|
|Dairy products, 2%||250ml||56|
|Whole grain bread||2 slices||32|
|1 large cooked egg|| ||24|
Source: DRI, Extenso.
Iodine deficiency is rare in North America because iodized salt is the most common source of iodine consumption. The most serious repercussion of iodine deficiency is the effect on the developing brain. To make thyroid hormones, the thyroid gland needs two other trace elements besides iodine: zinc and selenium. If an body is deficient in any of these three trace elements, thyroid function may slow.
Signs of iodine deficiency:
In healthy individuals, the amount of iodine needed for the body to function properly varies by diet, age, physiological state, physical activity, and medications taken.
The following groups should monitor their iodine intake:
Note: In industrialized countries, the blood TSH level of all newborns is checked at the hospital to determine whether or not they suffer from congenital hypothyroidism.
A large amount of iodine from foods is well tolerated by most people.
Signs of excess iodine:
As a supplement
Note: People can be allergic to iodine-containing products but not to the iodine itself. All products capable of triggering an immune response contain iodine, but the induced immunological response is caused by the other molecules, not the trace element.
Natural health products and vitamin supplements:
Speak with your pharmacist if you plan to take iodine supplements. Your pharmacist can help you choose the solution that’s best for you based on your health and any drugs you take.
Iode, Iodine, I