Iodine: Why You Need It, Why You Can't Live Without It by David Brownstein, MD

Iodine by David Brownstein, MDBacon Phat
00:00 / 58:45

Iodine: Why You Need It, Why You Can't Live Without It is an excellent companion to our Episode 6 book, The Thyroid Connection. It discusses a lot of useful facts about the importance of iodine to the thyroid and body.

 In this episode, we discuss:

Show notes:

Iodine has always been important

Iodine was the first isolated nutrient that scientists discovered was important for health in the United States. They quickly added it to salt to prevent goiter, which was widely prevalent in the Midwest. However, humans had already been supplementing with iodine to prevent goiter—they just didn’t know it. 3,500 years ago, the Chinese knew that eating seaweed and burnt sponge would prevent goiter, but they obviously didn’t realize iodine was the cause. 


Iodized salt is a major source of iodine in the Standard American Diet, but unfortunately it is not very bioavailable. While using iodized salt can be sufficient to prevent goiter, it cannot adequately supply all the iodine needed for “optimal thyroid function”. Dr. Brownstein says the only reason doctors don’t see iodine deficiency as a widespread problem is that they don’t test for it. If one has to live in a place that inherently has lower levels of iodine, it is best to get iodine naturally from sea vegetables and soil or high-quality supplements like iodoral

Halogens compete with iodine 

As we discuss in Episode 6, Iodine is crucial to health because it is required to make the various thyroid hormones. Iodine falls in the second-to-the-right column of the Periodic Table with a group of elements all missing one valence electron. These so-called “halogen elements” include chlorine, bromine, and the most reactive element in the PT, fluorine. Fluorine is present naturally in the earth’s crust and therefore our bodies, but it is rarely stored in its elemental state due to its reactivity. We do not believe that overconsumption of fluorine is a good idea for health, so we eschew things like fluoridated toothpaste and water. Just because elements are found naturally in our bodies does not mean that we can consume more of them without consequence.


The halogens compete with iodine in the body because they are chemically similar due to their missing valence electrons. However, it is not correct that halogens are similar in size. We disagree with Dr. Brownstein that one reason the elements act similarly is their similar sizes because the elements’ radii increase as you go down the PT. Fluorine has 9 protons and 9 neutrons, so its radius has to be smaller than iodine, which has 53 protons and various amounts of neutrons (Iodine has 37 known isotopes). In fact, because chlorine, bromine, and fluorine are all smaller than iodine and their valence electrons closer to their nuclei, it is harder to remove their valence electrons, making them more reactive than iodine and better able to take iodine’s place in the body.


Bromine is a common and highly toxic element in things like new cars, pesticides, and flame retardants. Fluorine, always in a compound form, is used in refrigeration systems, to make things like Teflon, and to fortify water and toothpaste. Chlorine is used in pesticides, synthetic rubber, plastics, solvents, paints, and more. Because these elements are so prevalent in our environment, they have ample opportunity to enter the body and reduce the body’s ability to take up iodine. The best solution is to avoid extra sources of them as much as possible. They are present in foods and nature naturally, but there is no reason to give the body extra work by eating conventional food, using conventional materials in homes and cars, and using toxic beauty and cleaning products.

Organification of iodine

Though we (and most other people) use the term “iodine” almost exclusively, there are two forms of iodine necessary for health. Iodine is the diatomic form of the element by itself, and iodide is the ionic form of the element in a compound with another element. (This is why iodoral contains both forms.) For example, iodide must be oxidized via thyroid peroxidase (TPO) to create iodine, which can be used to make T3 and T4, the body’s useful forms of thyroid hormone. Interestingly, hydrogen peroxide (a byproduct of ATP production) is a cofactor in this process, and when one is deficient in iodine, excessive hydrogen peroxide, which is toxic for most of the body’s cells, can build up.

Dr. Brownstein writes that vitamins B2 and B3 are also necessary for this process, so even if one is getting adequate iodine, she can still have a poorly functioning thyroid and excess hydrogen peroxide (and a cascade of other health issues) because she is not taking in enough B vitamins. (Hello vegans!) Inadequate selenium can also contribute to excess hydrogen peroxide because glutathione peroxidase is necessary for turning hydrogen peroxide back into water.

Other cool things

Iodinated lipids, such as delta-iodolactone, are necessary for more than just thyroid functions. Science tends to forget that the body is complex, and things have multiple uses throughout the body. Delta-iodolactone is necessary for programmed cell death to function correctly. Cancerous cells are successful largely because apoptosis, or programmed cell death, does not occur, and tumors proliferate indefinitely. Iodine deficiency is also implicated in several cancers because other parts of the body, including the breasts, eyes, thymus, pancreas, etc., use iodine to carry out their functions.


The body makes four types of estrogen. (On the podcast, we mistakenly say “three”.) Xenoestrogens, which are manmade chemicals that mimic estrogen in the body and interfere with normal hormonal processes, can increase one’s risk of breast cancer because they throw off the natural balance of the types of estrogen in favor of estradiol and estrone.


If one has an autonomous nodule on her thyroid, she should not necessarily supplement with iodine. The nodule is not responding to the hypothalamus and pituitary glands and is therefore not regulating T3 and T4 levels correctly. Supplementation with iodine in the presence of an autonomous nodule can result in hyperthyroidism.


Radioactive iodine is often the treatment prescribed for nodules on the thyroid because doctors want to kill the malfunctioning thyroid tissue. However, this practice is risky because it will accumulate in other places where iodine is used. Because the breasts use plenty of iodine as well, when one takes radioactive iodine, it will gather in the breast tissue, increasing the risk for breast cancer.

Major critiques

We love this book. It is helpful and a great little primer for important things to keep in mind about iodine and thyroid health. However, several concepts are not fully explained or explained well, and a lot of supplemental research and reading is needed to understand everything. The graphics aren’t great, either. 


Dr. Brownstein is an iodine genius. This book is crucial if you have any doubts that iodine is essential to your health. Or if you just need a refresher. It's good to remember that the body is complex and things we don't think about everyday are keeping us alive and need our attention. Read this book for an explanation of iodine's importance for the thyroid and several other biological processes, including apoptosis. Take the graphics and simplified explanations with a grain of salt, however. This book is an excellent jumping-off point, but you will need to read more sources for a pull picture of this life-saving element.


  • White Twitter Icon
  • White Instagram Icon