Have you ever heard of halides? Maybe you have, maybe you haven’t, but it’s something I have gotten a lot of questions about lately. That’s why I want to perform a deep dive into what they are, and what they mean for your thyroid function.

Curious about whether halides cause thyroid disease? Maybe whether you should test your halide levels? Or, if they displace iodine and create inflammation? We’ll cover all of that right now.

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Halides: Defined

Generally speaking, halides are all elements that can be found under the same column on the periodic table of elements (along with iodine) (Read: Everything You Need To Know About Iodine).

The thought is that because they share some similar properties, they could offset iodine or have some unique effects on the thyroid (and its iodine pump).

So, taking the big picture into consideration, let’s start with a clear understanding of what constitutes halides. They are as follows:

  • Fluoride
  • Chlorine
  • Bromine

The short answer is that they are mostly not a factor, but there are some special cases where they can be a factor, but in most cases, you won’t have to worry about them too much.

First: Fluoride!

We get a lot of fluoride from a lot of different sources.

In fact, there’s a fairly vast selection of foods which have fluoride in them, like:

  • Pickles (0.5 mg)
  • Spinach (0.3 mg)
  • Asparagus (0.2 mg)
  • Beets (0.15 mg)
  • Potatoes (0.1 mg)
  • Orange Juice (0.1 mg)
  • White Rice (0.06 mg)

Key Insight: Tea is quite dense in fluoride, but only small amounts of tea are ever truly ingested (because they are filtered through hot water and we don’t eat the tea itself).1

Essentially, fluoride at high doses can cause hypothyroidism. In fact, the lowest dosage that has this kind of effect on the thyroid is likely 5 mg per day.2

Bottom Line: It’s important to note, though, that this connection has not been shown to take place in dietary fluoride. It only happens in cases of supplementation.

What About Fluoride In Our Water?

This is a question that is often asked. If fluoride at certain levels causes hypothyroidism, what about fluoride in our drinking water?

Let’s turn our attention toward two key studies. One, from Canada, which suggests that water fluoridation in Canada has no relation to thyroid function.3

And another, this time in the United Kingdom, which found a possible link in certain areas that exceeded 0.3 mg/L.4

While it may have changed TSH slightly, it did not change rates of thyroid disease and it did not change active thyroid hormones.

All in all, areas with “endemic fluorosis” (fluoride toxic), like India and China, cause no clear change in overall thyroid. This is where areas had unsafe levels of fluoride in the drinking water due to geological sources.5

That said, there was no difference in thyroid function when compared against similar groups with normal fluoride exposure.

Key Insight: Some have wondered if fluoridated water causes cancer. Right now, there are no clear conclusions, but I can tell you that it is not likely to be the case.

In general, though, I’m a fan of purified water. So, while it will have fluoride removed, I avoid tap water for other reasons beyond the presence of fluoride.

What About Fluoride In Toothpaste?

There are roughly 1000 – 1500 parts per million (ppm) per gram dose of toothpaste. Ultimately, this adds up to about 1 – 1.5 mg of fluoride – if you are eating your toothpaste.

If you were not eating it, you wouldn’t be able to absorb it in significant amounts that it would make a difference to your thyroid.

The same can be said of when you go to the dentist and get fluoride treatments. There is no significant fluoride absorption at this point, either.

Action Steps: Fluoride

So, what can you do about fluoride?

The main thing to note is to avoid fluoride supplements.

On a daily basis, it is best to use purified, non-fluoridated water. This isn’t to avoid fluoride, but it’s just a good idea in general (Read: The Importance Of Water).

At the same time, it is best not to swallow toothpaste, or to use non-fluoridated in the event that you do (or if you do it by accident).

Bottom Line: Fluoride is really nothing to be worried about, as long as you avoid making toothpaste an essential part of your diet!

Next Up: Chlorine!

There have been theories about chlorine becoming an issue. This is because it too is a halide, and some have wondered if building it up in the body could end up displacing iodine.

In general, I have looked into halides being possible concentrated by the thyroid. That has shown to not be the case.

Basically, the pump that the thyroid uses to pull in iodine, that pump is not really attracted to the other halides in question.

Instead, when they circulate in the body, they do not become higher in the thyroid when compared to other areas in the body.

The uniqueness of iodine in the thyroid is that the amounts that are useful are far greater than the amounts the bloodstream carries.

Key Insight: Iodine only gets to do something in the thyroid, after the thyroid concentrates it.

In this case, the concentrator does not work on chlorine or bromine.

What Do We Know About Chlorine?

thyroid function

If you have ever been in a pool before, chances are you know chlorine well as an irritant.

It can cause some skin and eye inflammation, and is generally very difficult on the skin. This is especially true of pool levels of chlorine used to maintain pools.

In fact, high doses of chlorine is known to be a respiratory toxin. Indoor pools, at frequent exposure, may even be a risk for developing asthma.6

Ultimately, though, chlorinated water has no effects on thyroid disease in infants. There is a possible effect on subclinical thyroid disease in preterm infants, but its not statistically significant to where we could foresee a real trend.7

Key Insight: In fact, there is no effect on thyroid function in humans at 20 ppm.

When we pull it out further and look at chlorine’s effect on animals, we can see no lasting effect on thyroid function or iodine uptake in rats or monkeys.8,9

Chlorine: Action Steps

So, what can you do about chlorine?

Basically, it’s the same as fluoride, and the lesson there is that purified water is best.

In general, you should always be cautious of indoor, chlorinated pools, due to exposing your lungs to the chlorine for long, sustained periods of time.

Key Insight: Even from pool exposure, there is no proof to suggest that chlorine will change the way your thyroid works. You should avoid it for other reasons, though, as explained above.

Lastly: Bromine

So, just like fluoride and chlorine, does bromine cause thyroid disease?

One central claim, made by those in the Iodine Project, is that humans have a higher exposure to bromine than in the past (and that bromine increases iodine requirements).

It is also claimed that iodine pushes out store bromine from the body. Many of the apparently harmful effects from high-dose iodine are blamed on possible “bromine detoxification.”

Here are a few quotes, compliments of Dr. Brownstein:

“All foods that contain bromine need to be avoided. “
“Animal studies have shown that the ingestion of bromine can cause hypothyroidism. “

Dr. Brownstein based these claims on very specific research.10 In the study, iodine deficient rats were fed a diet containing 4000 – 16000 mcg of bromine per kg of body weight for 4 weeks.

Key Insight: Keep this in mind: a typical human intake of bromine is 0.03 – 0.125 mg/kg per day.

These iodine-deficient animals consumed somewhere between 32,000 and 533,333 times an average human dose.

That is why there are no conclusions from this study that can be drawn regarding bromine intake at normal human levels in populations that are not iodine deficient.

Key Insight: This study showed that bromine did not displace iodine even when used at such high levels. Only when animals were already iodine deficient did it affect thyroid function.

Bromine Toxicity

Let’s consider another quote: “Bromine toxicity can be present even with low levels of bromine in the diet.”11

For this one, Dr. Brownstein cited another study. This is where researchers concluded that: “all the findings were within normal limits.”12

Bromine had no measurable effects in any doses. So, what does this all mean?

Bottom Line: Basically, it is never good to simply call a substance good or bad. The more important question to ask is, “at what dose?”

Where Do We Get Bromine?

Much like iodine, we get bromine from the ocean. Our intake is largely from things like:

  • Fish
  • Shellfish
  • Produce grown in bromine-rich soil

For example, shrimp has 2.2 – 4.3 mg of bromine (per 100-gram serving).

What does it do to humans and their thyroid function? Let me walk you through two human studies to help illustrate how it works.

One study looked at thyroid function in healthy people and compared it to urinary bromine levels. They concluded that there was no significant relationship between bromine levels and thyroid function.13

The other study was a bit more useful, since it checked more markets of human health. It also gave bromine in doses much higher than what is typically ingested.

In a blinded human study, bromine (in three doses) was given to males and non-pregnant females for 12 weeks time.

The doses used were 0, 4, and 9mg of bromine per kg, per day. The normal daily intake is 2-8 mg per day in total.

For a 140 pound female, that would equal a range of 0.03 – 0.125 mg/kg per day.14

What they found were no changes observed in:

  • T4
  • Thyroid Binding Globulin
  • Cortisol
  • Estradiol
  • Progesterone
  • Testosterone
  • TSH
  • Prolactin
  • LH
  • FSH

In addition, there were also no changes in general blood chemistry or urinalysis.

Key Insight: One interesting finding was that women who were ingesting 300 times more bromine than normal had an increase in both T3 and T4.15

Too Much Bromine?

All that said, there is a point where we can get too much bromine. But, it turns out that there is also a point where we can get too little.

Dr. Brownstein initially stated that: “There is no known therapeutic value for bromine…any level of bromide could possibly cause problems.”16

Now, we know otherwise.

Since the initial reports on bromine, we have learned that it is a nutrient essential to human life. In fact, in 2014 it was named the 28th known essential element.

Much of its utility revolves around collagen formation. Specifically, it is essential to forming Type IV collagen and sulfilimine.17

These structures are essential to many parts of the body, including:

  • Kidney membranes
  • Blood vessel linings
  • Nerve tissue

Key Insight: A lack of bromine can also trigger the autoimmune disease called Goodpasture’s syndrome.18

Why Didn’t We Know This?

The reason that bromine deficiency was not apparent in the past is because the amounts needed are easily supplied by typical diets.

We have observed bromine deficiency issues in smokers, and in some with genetic variations, those only consuming intravenous nutrition, and in those on dialysis.

Key Insight: Smokers are more at risk for bromine deficiency due to the high amount of thiocyanate they are exposed to.

Most excess bromine can be harmlessly excreted through the kidneys. But, like all things, too much can be toxic.

The intake required for toxicity is several hundred milligrams per day at a minimum.19

Is Bromine Dangerous?

No. Humans taking much more bromine than they ever could from their diets or typical environments had no measurable effects on their health.

In fact, those on the highest doses have had improvements of their thyroid levels.

A Summary On Halides

So, what’s the truth about halides? Let’s break each of them down based on what we discussed today – and what you need to know.


Chlorine is a lung irritant, but it is not known to displace iodine or concentrate in the thyroid. Overall, the data is mixed, but high oral intake may raise the risk of some cancers.


This is an essential nutrient. It is not a toxin in dietary doses, and it does not change thyroid function (even in extremely high dosages).

It is true, though, that some highly-processed foods contain brominated compounds. These are unhealthy foods on their own, though, and the bromine has no effect.


Of the halides, fluoride is the only one that may disrupt thyroid function. You can find various amounts of it in tea, food, fluoridated water, or dental treatments.

That said, none of them are provided in amounts that would be impactful.

The major thing to note is that fluoride in supplements can be a factor. This is especially true if it exceeds 5 mg daily.

Bottom Line: There are cases where high-dose fluoride supplementation may be used to treat hyperthyroidism.

Halides & Your Health

Fluoride, chlorine, bromine, all of these halides come with their own set of information. It’s important, though, to know the truth about your health.

That’s where the Thyroid Quiz (Click Here: Take The Thyroid Quiz) comes into the picture. It can help provide you with the information you need, and the steps you can take, to aid your health.

Go ahead, give it a shot today, and put your health back on track.


1 – https://www.sciencedirect.com/science/article/pii/S0269749117328282
2 – http://journal.unpad.ac.id/pjd/article/download/14151/6829
3 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5754860/
4 – https://jech.bmj.com/content/69/7/619.full
5 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3890436/
6 – https://www.ncbi.nlm.nih.gov/pubmed/19061232
7 – http://sci-hub.tw/10.1080/00039890409603437
8 – https://www.ncbi.nlm.nih.gov/pubmed/3761383
9 – https://www.ncbi.nlm.nih.gov/pubmed/4043591
10 – https://www.ncbi.nlm.nih.gov/pubmed/2135954
11 – https://www.amazon.com/Iodine-Need-Cant-Live-Without/dp/0966088239
12 – https://www.who.int/water_sanitation_health/dwq/chemicals/Fourth_Edition_Bromide_Final_January_2010.pdf
13 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC501258/pdf/jclinpath00206-0074.pdf
14 – https://www.who.int/water_sanitation_health/dwq/chemicals/Fourth_Edition_Bromide_Final_January_2010.pdf
15 – https://www.ncbi.nlm.nih.gov/pubmed/6684622
16 – https://www.amazon.com/Iodine-Need-Cant-Live-Without/dp/0966088239
17 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4144415/
18 – https://etd.library.vanderbilt.edu/available/etd-03242013-212240/unrestricted/Cummings_Dissertation_Final.pdf
19 – https://www.ncbi.nlm.nih.gov/pubmed/2484543[/vc_column_text]
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Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.

Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.