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iodide and iodine

What’s the Difference Between Iodide and Iodine?

Last modified: May 17, 2023

Reading Time: 5 minutes

Iodide and iodine are two essential substances that are commonly used in various fields, including medicine, chemistry, and technology. Although they have similar names and functions, they have distinct properties and applications. In this article, we’ll explore the differences between iodide and iodine, their uses, and their importance in our daily lives.

Iodine is a naturally occurring element necessary for the human body’s growth, development, and metabolic functioning. In contrast, iodide is an ion of Iodine, which make iodine bond with other elements, including potassium, and form potassium iodide.

Iodine is one of the rarely occurring earth elements essential for life, primarily found in the oceans. This article will discuss the fundamental difference between Iodine and iodide. The role of Iodine in the functioning of the thyroid gland and how iodine deficiency leads to causing thyroid diseases and other health issues will also be addressed.

What is elemental Iodine?

Iodine is a vital micronutrient located mainly in the thyroid gland. Still, it can also be stored in muscles, skin, and fat cells. Iodine can exists either in elemental form or bond with other elements and makes either potassium iodide or sodium iodide.

iodide and Iodine found in nature

In the case of elemental Iodine, two atoms of iodine bond together and form I2, which is absorbed by the thyroid gland in a minimal amount. This elemental form of Iodine is not present naturally. It will not be ingested or directly applied to the skin due to its corrosiveness and cause severe tissue damage [1].

Are there any other forms of Iodine?

Iodine mainly exists in diatomic molecular/ elemental Iodine (I2) and monoatomic iodide (I-) forms. In its iodide form, Iodine can be ingested or applied on the skin as it is less corrosive. Naturally present iodide, either as potassium iodide or sodium iodide, can be used as Dietary Iodine and can also be used to make table salt. The body can easily absorb the iodide form to be used safely.

Iodine and iodide are considered as changed expressions of the same element. Iodides are a safer form of Iodine for ingestion but require additional energy to break the iodide bond to use the Iodine in the body [2].

How is iodide different from Iodine?

Elemental Iodine (I2) has two iodine atoms covalently bonded together. The elemental form of Iodine can’t be ingested easily, or it can’t be directly applied to skin or tissue because of its high corrosiveness. However, this diatomic form of Iodine can be formed commercially by oxidation of brine-containing iodide ions to precipitate them to form Iodine (I2) crystals [3].

While iodide is a vital element present in nature, it usually exists as a salt with another element like calcium, sodium, or potassium. Therefore, it can easily be applied to the skin and quickly be taken up by the body. Dietary Iodine is also present in the iodide form that can be obtained from seaweeds and used as iodized salt. This form is essential for the standard production of thyroid hormones.

Why do you need sufficient Iodine?

Iodine is essential for synthesizing thyroid hormones, including triiodothyronine (T3) and thyroxine (T4). These hormones help in the metabolic processes of cells with DNA, except mature RBCs, because they don’t have DNA. They also play a role in most organs’ growth and development at an early stage, especially the brain.

thyroid hormone

Iodine deficiency can lead to different thyroid diseases, including thyroid cancer, and can also cause breast cancer in women [4]. If we are not consuming enough Iodine, then the human body usually can’t work. So, a person can take iodine supplements without getting enough Iodine through dietary sources.


1. ND DEFGI DC. How are Iodide and Iodine Different? [Internet]. Dr. Group’s Healthy Living Articles. 2013 [cited 2022 Oct 15]. Available from:

2. Iodine or Iodide: What’s Really in Our Supplements? [Internet]. Restorative Medicine. 2017 [cited 2022 Oct 15]. Available from:

3. Iodine [Internet]. [cited 2022 Oct 15]. Available from:

4. Iodine vs. Iodide – What’s the Difference? | Magnascent [Internet]. 2016 [cited 2022 Oct 15]. Available from:


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