High Dose vs Low Dose Iodine: Which Should you use?

One of the best things about iodine is that it's an over the counter supplement which is available to almost everyone. 

Iodine, as a therapy for thyroid disease, can be extremely effective and is within the reach of everyone reading this. 

It's cheap, effective, and doesn't require a prescription to get. 

That being said, there are some potential downsides to the use of iodine, especially in the setting of existing thyroid disease. 

In this article, we are going to explore the difference between iodine dosages and talk about which dose you should be using. 

In addition, we are going to set the record straight on iodine and discuss why most people need it. 

Iodine and Thyroid Disease

There is no shortage of controversy surrounding the use of iodine, especially in the setting of thyroid disease. 

There are groups of people, who I still encounter to this day, who believe that iodine is a harmful nutrient or even worse, a toxin of some sort that will damage their thyroid if they take it. 

This kind of logic stems probably from an incorrect interpretation of certain studies which show that there may be a link between the development of Hashimoto's thyroiditis (1) and the use of iodine. 

These studies have shown that as developed countries have increased their consumption of iodine that the rates of Hashimoto's have climbed in lock-step (2). 

This has led many researchers (and doctors) to conclude that iodine is somehow responsible for this increased rate of thyroid disease. 

But a deeper look at the research doesn't really point to that conclusion. 

Instead, it suggests that the development of Hashimoto's thyroiditis is a complex disease with multiple moving parts. 

And iodine supplementation, in the right setting and with the right nutrient deficiencies, may trigger an inflammatory process in the thyroid gland which can trigger Hashimoto's thyroiditis. 

But this is not the same thing as guaranteeing that using iodine will cause Hashimoto's nor does it suggest that using iodine is harmful or should be avoided. 

On the contrary, we actually know, and have scientific proof to back it up, that iodine is an essential nutrient for thyroid function (3). 

Avoiding iodine, or becoming iodine deficient, is a quick way to CAUSE thyroid disease or worsen your existing disease. 

The avoidance of iodine, even in the setting of Hashimoto's thyroiditis, may actually be making your thyroid WORSE. 

Whether or not iodine is helpful or harmful depends largely on your body and how you are using it. 

What dose you are taking, when you are taking it, and what you are taking it with matter a lot when it comes to using iodine. 

We are going to have a discussion on each of these points and talk about how you can use iodine safely so that it doesn't cause any problems. 

Using it in this way may, on the contrary, actually improve your thyroid status and make you feel better. 

I've found very few over the counter therapies which can have the potential positive impact on the thyroid as iodine can.  

3 Different Categories/Doses of Iodine Use

We know that humans have no way of producing iodine on their own. 

Because of this, you MUST be consuming iodine either from your diet or from supplements to get it. 

Most dietary iodine comes from animals and plants that grow in the ocean where iodine is concentrated. 

Because most people, especially in the United States, don't consume sea vegetables (like kelp or nori) on a frequent basis, the government has fortified certain foods with iodine (4) to supplement. 

The only problem is that most of these foods are not considered to be "healthy" and so may be avoided accidentally by people who are actually health conscious! 

When you combine this with the fact that many individuals don't consume sea vegetables, and that many thyroid patients are weary or just scared of using iodine period, you get the perfect set-up for iodine deficiency even in developed countries. 

There is a strong case for supplementation given these facts which is why we need to have a discussion on doses. 

As I mentioned previously, how much iodine you take can dramatically have an impact on thyroid function (either for the positive or for the negative). 

Take a dose too small and you may remain deficient. 

Take a dose too high and you may cause inflammation or trigger an autoimmune process. 

So which is the right dose? 

There are really 3 categories of iodine use that most people are aware of. 

Note: your current doctor is probably not aware of any of these, but they exist in the community and each has a following of people who support their use. 

Low Dose Iodine

Low dose iodine consistent of doses of iodine within the "normal" RDI range. 

The RDI (recommended daily intake) set forth by governments is around 150-270mcg of iodine per day (5). 

RDI for iodine in adulst men and women

Make sure you take note that we are talking about MICROGRAMS here and not MILLIGRAMS because this will be important in further discussions. 

The RDI is simply a calculation based on studies and other factors which attempts to describe a dose which is enough for around 95% of the population. 

There are plenty of reasons to be wary of the RDI dose for many nutrients as they often tend to be very conservative values. 

In addition, they simply don't account for 5% of the population which may need more or less iodine (or any nutrient). 

The good thing about low dose iodine is that it is considered a very safe dose for most people. 

In fact, low dose iodine, around this range, is what you should target to AT LEAST consume on a near-daily basis. 

You don't need to worry about getting in 150-270mcg per day so long as you get an average dose of around that age over a couple of weeks to a month. 

Dosing in this range is safe because you are limiting the risk of a thyroid response to iodine which can occur with high doses of iodine (known as the Wolff-Chaikoff effect (6)). 

I personally like to start certain patients on low dose iodine because you can always titrate up from the low dose as the patient proves that they can tolerate the low dose. 

This method works particularly well for patients who are very sensitive or who have had issues with iodine in the past. 

*Note: even if you've had iodine issues in the past does not prove that you will not be able to tolerate it in the future!

But I should point out that not everyone has to start out on this low dose. 

In fact, I've only ever used high doses of iodine in my life (as well as many of my family members and current patients) without any issue. 

One downside to using low dose iodine is that it probably only helps you maintain current iodine levels without actually repleting iodine stores in your body. 

We know, for instance, that your body can store up to 15-20 mg (7) (that's milligrams) of iodine in the tissues and thyroid gland. 

To help you understand the numbers here you need to understand that 1,000mcg is equal to 1 milligram. 

So using a dose of 150 to 270mcg (micrograms) is probably not enough to ever help iodine get to all of those tissues even if you use it every day. 

Furthermore, if you miss a day here or there you are probably riding on the cusp of iodine deficiency. 

Because of this, while I do like low dose iodine and use it frequently (one of my favorite thyroid support supplements contains low doses of iodine), there is a time and a place for higher doses of iodine. 

High dose Iodine

When I refer to high doses of iodine I want to distinguish between high doses and very high doses (we will talk about the latter in a minute). 

High doses of iodine, at least for the purpose of this article and discussion, are doses of iodine ranging from 6mg (that's milligrams) to 12.5 (milligrams) per day. 

Low dose iodine doses would be basically anywhere between 150mcg and a couple of milligrams per day. 

There are several reasons to suggest that high doses of iodine in the 6mg to 12.5mg range are healthy, safe, and effective. 

The strongest argument is probably the fact that there are humans on the Earth right now who consume close to this amount of iodine on an almost daily basis. 

There are studies from certain populations of Japanese (8) which show that these populations consume anywhere from 1 milligrams to 12 milligrams of iodine every day (depending on which study you look at) and have low rates of breast cancer (9) (where iodine concentrates) and thyroid disease. 

It's hard to make the argument that iodine in high (moderately high doses) is dangerous when there are many people around the globe (10) who consume large doses of iodine and are in great health (11). 

When using iodine it's important to remember that more tissues than just your thyroid require this important nutrient. 

We focus on the thyroid gland because it obviously has a very high demand for iodine but other tissues such as the skin and breast tissue also have need for it. 

The fact that other tissues require iodine is another reason that higher doses can be well tolerated and even healthy. 

Even if you opt to use higher doses of iodine (in the 6mg to 12.5mg range) you don't have to use it every day. 

You can break up your dose to obtain an average smaller dose simply by taking it once per week or on some similar schedule. 

Once a week dosing with 12.5mg of iodine will provide your body with an average dose of 1.7mg per day of iodine. 

Once per month dosing of 12.5mg of iodine will provide your body with an average dose of around 400mcg of iodine each day. 

As someone who does not have thyroid disease, this is how I typically take iodine. I use a supplement which contains both elemental iodine and potassium iodide every few weeks to keep my iodine stores up. 

My wife on the other hand, who does have thyroid disease, takes the same supplement which contains 12.5mg of iodine each and every day. 

The higher doses of iodine tend to get a bad reputation but are very well tolerated by most people. 

If you are sensitive, however, you should consider starting at the lower dose of iodine first just to ensure that you don't experience any negative effects. 

You can always slowly increase your dose over time to reach the higher levels. 

Very High Dose Iodine

I want to bring up very high dose iodine, not because I recommend it but because you should be aware of it. 

Unlike low dose iodine and high dose iodine, I do not believe that there is a time or place for the use of very high doses of iodine. 

Very high doses of iodine would include doses that range from 25 mg (milligrams per day) all the way up to 50 mg (milligrams) per day. 

These incredibly high doses are sometimes recommended by providers and forums around the internet but I do believe they can be dangerous. 

I've seen numerous accounts of individuals who use doses in this very high range who CREATE thyroid problems seemingly out of nowhere. 

These people are in the comment sections of my blog and youtube videos and have been frequent enough to give me pause when recommending very high doses of iodine. 

I simply don't believe there is any evidence that incredibly high doses are any more effective than low dose iodine or moderately high dose iodine (in the 6mg to 12.5mg range). 

The high doses of iodine are sufficient to help with repletion and should be preferred over very high doses of iodine. 

If you are considering using these very high doses of iodine I would be very cautious of this approach. 

Even if it isn't harmful right away you have to ask yourself why would you opt for these doses over smaller more safe doses of iodine.

Side Effects Associated with Iodine Use

Even when used in appropriate doses it's still possible that you may experience certain side effects with iodine use! 

These side effects do not mean that you need to stop using iodine but they may be an indication that you should back off on your dose. 

Low doses of iodine don't seem to have a strong effect on the thyroid gland but higher doses may start to impact both thyroid function and your thyroid gland. 

The thyroid gland has a protective mechanism built-in which blocks the update of excessive doses of iodine to prevent states of hyperthyroidism. 

Moderately high doses of iodine can trigger this response and may explain specific changes in thyroid function in the short term. 

But just because this can happen doesn't mean you should be scared of it occurring. 

Even when it does occur this effect tends to be minimal. 

In addition, and at least in my experience, you are much more likely to experience positive side effects (such as an increased production of thyroid hormone) as opposed to negative side effects. 

Other side effects with iodine use may include:

  • Fatigue
  • Nausea
  • Rashes/hives
  • Sensation that your thyroid is swollen (if this occurs you should stop iodine supplementation)

These side effects can and should be minimal if you are using appropriate doses of iodine but you should be aware of them. 

The side effects listed above tend to stem from the thyroid gland directly. 

But it is my opinion that taking iodine by mouth may also have a direct impact on existing thyroid hormone that is already produced in your body. 

This may be why some individuals who take iodine notice an almost immediate improvement in their symptoms. 

The reason that this may occur is probably related to the structure of iodine and how it may displace other halides which share a similar electron outer shell. 

It has been theorized (but not proven to my knowledge) that halides (bromine, chlorine, fluorine) may displace iodine on thyroid hormones molecules. 

This may happen because all of these chemicals contain a similar electrical charge. 

Normally, each thyroid hormone contains 4 (for thyroxine) or 3 (for triiodothyronine) iodine molecules on it. 

But you can imagine that, in some instances, one or more of these iodine molecules may be displaced by these other chemicals. 

If that occurs they may render the thyroid hormone molecule inactive which would then cause a mismatch between your thyroid lab tests and your clinical presentation. 

Imagine if even a small number of thyroid molecules in your body were inactive. 

Your lab tests might show that your serum levels of T4 and T3 were normal but they wouldn't be able to tell you how well these molecules are working. 

By giving yourself iodine, in supplement form, you could create an environment where these halides might be displaced from thyroid hormone molecules and render them active again due to competitive binding. 

If this occurs (and I believe there's good reason to believe it does) then the use of iodine could almost instantly improve thyroid function in your body through this mechanism.

It's my belief that this mechanism not only explains why thyroid patients do better on higher doses of iodine but it also explains why some people feel almost immediately better when using it. 

Is this happening in every patient? I don't believe so but I do think it's happening in more patients than we probably think. 

And the reason I came up with this idea was because of my own experience. 

When I used high doses of iodine I noticed breakouts in my skin that would appear and quickly disappear within a day or so. 

And these skin changes were consistent with a condition known as bromoderma which is what occurs when your body eliminates excess bromide (a halide). 

When it does occur I've seen patients tend to experience a quick rush of negative symptoms (flu-like symptoms, breakouts, acne, feeling fatigued, and so on) as the body attempts to eliminate these halides out. 

So if you've ever experienced these symptoms while taking iodine it may actually be a good thing related to a detox-like reaction and not a negative side effect or even a reason to stop using iodine. 

What Dose should you take? 

If you aren't sure what dose to take then you can use these guidelines to help: 

  • For 70-80% of thyroid patients (especially those who are supplementing regularly with zinc and selenium) then starting out in the 6mg to 12.5mg range shouldn't pose any problem. I would recommend 1 capsule per day of a supplement such as this which contains both iodide and iodine. 
  • If you have experienced issues with iodine in the past or you are sensitive to small doses of medications and supplements then you will want to start out with 100mcg per day and slowly increase your dose over time. You should still be able to get to higher doses over time but it may take a while. 
  • At this time I have no recommendations for using doses of iodine higher than 12.5mg per day

Using Iodine with Selenium

I touched on this previously but I want to make sure we go into it in a little more detail here. 

It's important to understand that there is probably a connection between iodine use and damage to the thyroid gland but only in the setting of co-existing selenium deficiency. 

Selenium is necessary for the production of powerful antioxidants such as glutathione. 

A lack of selenium (selenium deficiency) may set you up for inflammation in the thyroid gland if you are also using iodine. 

We even have studies to suggest this is the case (12). 

But what's interesting is that as long as you replete your selenium (and zinc and other nutrient deficiencies) before you take iodine this shouldn't be an issue. 

How do you know if you have sub-optimal selenium levels?

My way of thinking about nutrient deficiencies simple:

If you have one nutrient deficiency then there is a very high probability that you have other nutrient deficiencies. 

I operate under the assumption that you are deficient unless you are currently already using a broad multivitamin or if you've used a moderate dose of selenium or zinc recently. 

If you haven't then you should assume that you are deficient and you should use these nutrients con-currently (meaning at the same time) as iodine. 

I also wouldn't recommend that you look solely at your serum (blood) markers as a way of assessing whether you are deficient or not. 

Blood tests are not an accurate way to assess for iodine deficiency or for most other nutrient deficiencies and may lead you astray. 

So what should you do?

I would recommend you simply supplement with a good thyroid friendly multivitamin for a few months (2-3 months should do the trick) either before you take iodine or at the same time. 

A good multivitamin will have all of the necessary micro-nutrients and vitamins that your thyroid gland needs and will provide adequate protection against iodine-induced damage. 

You can probably find all of these ingredients as standard in most high-quality multivitamins (but be wary of store-bought multivitamins). 

Conclusion

The one thing I want you to get out of this article is the fact that iodine plays an important role in thyroid hormone regulation and it should not be avoided by the majority of patients with thyroid disease (even those with Hashimoto's). 

Dosing of iodine should be personalized and, if possible, addressed with your current physician. 

You should be aware, however, that many physicians are probably not aware of the nuances associated with iodine supplementation and may only recommend dosing in the low range or RDI range. 

For many of you, starting out at higher doses (in the 6 mg to 12.5mg range) may provide an almost immediate benefit and help improve thyroid stores. 

For those who are sensitive, starting out in the lower range (150mcg to 270mcg per day) may be a safer alternative. 

Now I want to hear from you:

Are you currently taking iodine? 

Have you noticed any improvement in your symptoms?

Have you noticed any negative symptoms? 

What dose are you currently taking?

Leave your questions or comments below!

References (Click to Expand)

Dr. Westin Childs

Dr. Westin Childs is a Doctor of Osteopathic Medicine. He provides well-researched actionable information about hormone-related disorders and formulates supplements to treat these disorders.He is trained in Internal Medicine, Functional Medicine, and Integrative Medicine. His focus is on managing thyroid disorders, weight loss resistance, and other sex hormone imbalances.You can read more about his own personal journey here.

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