Iodine
Iodine is an essential mineral element required by the body in very small amounts for the normal functioning of the thyroid gland.
It is essential for the synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3), which are involved in the regulation of energy metabolism, growth, and development.
In the human body, most iodine is concentrated in the thyroid gland.
In foods, iodine may occur naturally or be added in the form of compounds such as potassium iodide or potassium iodate, for example in iodised salt and certain fortified foods.
The main natural dietary sources include fish, shellfish, seaweed, milk and dairy products, eggs, and, in variable amounts, other foods.
The iodine content of plant foods depends strongly on the amount present in the soil and growing environment.
Seaweed can contain very high and highly variable amounts of iodine, so it does not always provide a predictable intake.
Prolonged iodine deficiency can impair normal thyroid hormone production, while excessive intake can also interfere with thyroid function, particularly in susceptible individuals.
Calories
Iodine provides 0 kcal.
Like other minerals, it is not used by the body as an energy source and does not directly contribute to the calorie content of foods.
The calories in a product containing iodine therefore come exclusively from other components such as carbohydrates, fats, and proteins.
Uses in Food
Iodine is used mainly for food fortification and to help prevent insufficient dietary intake.
The most common example is iodised salt, to which iodine compounds are added in controlled amounts.
It may also be present in food supplements, products intended for specific nutritional needs, and fortified foods.
In some products, iodine may be provided as potassium iodide, potassium iodate, or other permitted sources of iodine.
Iodine naturally present in foods contributes to normal thyroid function and normal production of thyroid hormones.
The amount required is very small compared with minerals such as calcium or potassium, so avoiding both deficiency and excessive intake is important.
Uses in Cosmetics
Elemental iodine is not commonly used as a conventional cosmetic ingredient.
Some iodine-containing compounds may, however, be used in products applied to the skin or in formulations with specific technological functions.
Povidone-iodine, known for its antiseptic activity, is mainly associated with medicinal and disinfectant products and should not be considered equivalent to a conventional iodine-containing cosmetic ingredient.
Other iodinated derivatives may be used in specific industrial formulations, but their properties and safety always depend on the specific chemical compound and its concentration.
Iodine used as a nutritional micronutrient should therefore not be considered equivalent to iodinated derivatives used in dermatological or pharmaceutical products.
Allergens
Iodine is not a food allergen and is not among the allergens subject to mandatory declaration in the European Union, United Kingdom, or United States.
The expression “iodine allergy” is often misleading: reactions to iodinated contrast media, medicines, or iodine-containing products do not necessarily mean that a person is allergic to iodine itself.
Reactions may nevertheless occur to specific compounds or to other components present in a formulation.
The amount consumed is particularly important because excessive iodine intake can cause changes in thyroid function even in the absence of an allergic reaction.
Evaluation
Iodine is an essential micronutrient required for thyroid hormone production and normal metabolism.
Adequate intake is particularly important during periods of increased physiological requirements, while both deficiency and excessive intake can have adverse effects.
Ingredient verdict: an essential mineral required for normal thyroid function; beneficial in nutritionally appropriate amounts, while insufficient or excessive intake may disrupt thyroid balance.
Cons: excessive intake may interfere with thyroid function; particular caution may be appropriate for people with thyroid disorders or increased sensitivity to iodine intake
