Why restricting your iodine intake when you have Hashimoto's might be hurting you

Your body (thyroid, breasts, ovaries, etc.) needs iodine

When I was first diagnosed with Hashimoto’s thyroiditis (aka autoimmune underactive (hypo) thyroiditis) back in 2018, I was referred to an endocrinologist who recommend I stop taking iodine.

Back then, I was on a daily multivitamin containing iodine.  I stopped the multivitamin switching to one that didn’t contain iodine and beyond that didn’t really adjust my diet.  In case you’re wondering, common food sources of iodine are fish and shellfish, seaweed, and dairy.

Within about a month, I developed a painful breast cyst.  Turns out, your thyroid isn’t your only organ that needs iodine.

Before we get into what other organs in your body need iodine, let’s talk about the elephant in the room.  This news may come to you in direct opposition to what you’re hearing from your own doctor.  For some reason, I didn’t put two and two together until a couple months ago when I clicked on a podcast about the thyroid gland and iodine. 

I nearly fell out of my chair when I heard the doctor being interviewed propose a restricted iodine intake for people with autoimmune thyroid conditions, specifically hypothyroidism.  He went on to say the thyroid sequesters iodine (which technically is true as do other organs in your body using the sodium/iodide symporter) and this makes it important to be sure you’re not getting too much (last I checked, your body does this for itself... it's a lot smarter than we give it credit for). 

I guess when my endocrinologist prescribed a low iodine diet, I was thinking this was more as a way to reduce thyroid function and thereby help reduce the body’s attack on it.  Hearing this view that iodine is sequestered by your thyroid and you need to tightly regulate your consumption was in direct contradiction to everything I’d read.

Because here’s the rest of the story.  Other halogens, like chlorine from chlorinated water and fluorine from fluoridated water, in other words, if you’re drinking tap or bottled water in the States, you’re seeing these compounds on a daily basis. 

Even if you’re drinking water from a non-chlorinated source and a non-fluorinated source, if you’re getting salt in your diet, which is sodium chloride, the chloride ion in the salt competes with iodine in your body, and because chlorine and fluorine are both stronger halogens, they displace iodine in your body. 

Perchlorate, which is a water soluble compound used in fertilizers is a competitive inhibitor of the iodide/sodium symporter, which concentrates iodine in thyroid cells.  Perchlorate has 30 times stronger affinity for the iodide/sodium symporter than iodine. 

In the thyroid, iodine is incorporated into the structure of T3 and T4 thyroid hormones.  The thyroid isn’t the only organ that express iodine/sodium symporters.  Breast tissue, prostate, gastric mucosa, skin (specifically the epidermis), salivary glands, the cervix, and choroid plexus within the brain also concentrate iodine.

Here's how sufficient levels of iodine is related to health in each of these organs:

Iodine and your breasts

A large body of scientific literature shows that iodine can reverse fibrocystic breast disease and also prevent and treat breast cancer.  While some of these studies are simply looking at the correlation between dietary iodine and breast cancer, studies are abundant evaluating the effects of iodine and breast cancer outcomes in animal models, human breast cancer cells in petri dishes, and in human clinical trials.

One study published late in 2016 shows compelling results that iodine inhibits growth of breast cancer cells and induces breast cancer cell death1.  This study was conducted in vitro (in a petri dish), at least 3 human clinical trials show that fibrocystic breast tissue is reduced or eliminated by iodine supplementation, and researchers believe fibrocystic breast disease is a precursor to breast cancer2.

While the why iodine is so beneficial for breast health is still being researched, iodine seems to play a multifunctional role in maintaining healthy breasts by:

  1. Desensitizing estrogen receptors in the breasts
  2. Reducing estrogen production in overactive ovaries
  3. Increasing progesterone production
  4. Triggering cell cycle differentiation. This is important because cancer cells typically display characteristics of undifferentiated cells.
  5. Decreasing peroxidation of lipids, which are oil soluble compounds like fatty acids and oil soluble hormones (basically iodine acts as an antioxidant). Just in case you’re wondering which hormones are fat soluble, here’s a short list:  estrogen, progesterone, testosterone, cortisol, and aldosterone
  6. Iodine is also concentrated in breast milk because it’s important to newborns
  7. In human breast cancer cell lines, molecular iodine inhibits induction and proliferation of breast cancer cells, induces cell death (apoptosis), and displays antioxidant activity

Iodine and Ovarian Health

Several studies show that the symptoms of polycystic ovarian syndrome (PCOS) are relieved by supplementing with iodine, namely iodine helped restore normal menstruation3

In fact, restoring normal menstruation cycles is something that iodine is cited to help with regardless of whether you have PCOS or not.  Now, the reason iodine helps with this may be that subclinical (undetectable by blood tests) or undiagnosed hypothyroidism3,4 is present in women with irregular menstrual cycles or their hypothyroidism just hasn’t been diagnosed yet.  Aside from the thyroid, your ovaries contain the highest levels of iodine in your body.

It appears that your ovaries are able to convert T4 (a thyroid hormone) to T3 (another thyroid hormone)5.  And, for all women out there who are pregnant, want to become pregnant, or are breastfeeding, iodine deficiency has been linked to abnormal fetal development and mental development of babies, toddlers, and children7

Iodine and Testicular Health

An NHANES epidemiologic follow-up study found that men with the highest ratio of urinary iodine to creatinine had nearly a 30% reduced risk of prostate cancer compared with men with the lowest ratio.  And, a history of thyroid disease doubled the risk of prostate cancer.  Men who’d had thyroid disease for more than 10 years had over 3 times increased risk of prostate cancer.

Men who are treated with radioactive iodine for thyroid cancer tend to experience problems with sperm damage that is directly related to the dose of radioactive iodine received during the course of treatment8.

Structures of the thyroid hormones T3 and T4.

Iodine and Skin Health

Iodine and iodine containing compounds are commonly used as topical antiseptics in preparation for surgeries.  Because iodine can cause a rash in people who are sensitive to these iodine containing compounds and that rash looks a lot like acne, iodine is blamed for being the reason why dairy contributes to acne.  The theory is that cows get iodine from salt blocks (though it's unclear whether those salt blocks are commonly composed of iodized salt0 and their milk, like human breast milk, concentrates the iodine.

Additionally, typically the antiseptic used to rinse the cow's udders contain iodine, which may be another source of iodine in dairy.

Here's the thing, for sensitive individuals, iodine containing compounds cause an acne like rash that appears rapidly upon exposure.  It's not acne.

Back in 1961, researchers took a look at adolescents who ate a diet rich in iodine (consuming seafood and fish) and found lower rates of acne in those teens.  To be fair, the omega-3's found in fish are also therapeutic for acne.

One more note here.  Before 1980, iodine was used as a dough conditioner in baked goods.  Iodine in bread was replaced with bromide, another halogen, that competes with iodine receptors in your body. 

Potassium bromate, the specific compound used for bread making is outlawed in Europe.  So, for anyone who's ever been to Europe and eaten bread just fine even when you have a sensitivity here in the States, this may be part of the reason. 

Iodine and Fetal Development

If you’re pregnant, your fetus needs thyroxine from you for normal development.  Significant iodine deficiency and hypothyroidism during pregnancy can cause growth abnormalities, neurological defects, and retardation in newborns.

Additionally, low iodine levels during breast feeding are associated with eczema in babies.

Iodine and Brain Function (including ADHD)

Iodine is also linked with IQ and ADHD.  One study found that children with urinary iodine levels above 100 micrograms per liter have a significantly higher IQ compared with children having urinary iodine levels below 100 micrograms per liter.  Another study evaluated psychomotor development relative to free thyroxine levels.  Children born to mothers with a free thyroxine level in the bottom 25th percentile had more than double the risk of developmental delay at 18 and 24 months old.

Of children diagnosed with ADHD, about 64% were born to mothers who had become hypothyroid during early gestation. 

Iodine Intake and other Bodily Functions

One study, conducted in mice, evaluated the effects of iodine intake on triglyceride and cholesterol levels.  This study found that iodine deficiency correlated with higher low density lipoproteins (LDL, better known as the bad cholesterol), higher triglyceride levels, and higher total cholesterol. 

A second group of mice in this study were fed a diet with excess iodine.  After 8 months, the females in this group had lower total cholesterol levels, and the males in this group had lower triglyceride levels than the iodine deficient group9.

A correlation, which again, is not evidence of causation, has also been noted between incidence of stomach cancer and dietary iodine levels.  As dietary iodine goes up, incidence of stomach cancer goes down.

How much iodine should you take?

The Food & Nutrition Board recommends 150 micrograms per day for adults.  Nearly double that is recommended for pregnant women and lactating women10

The population of Japan consumes nearly 100 times the RDA for iodine3 and has a low incidence of hypothyroidism and breast cancer.  Studies using 3 to 6 milligrams (20 to 40 times the RDA) of iodine effectively treated fibrocystic breast disease11.  It is unclear whether the iodine intake in that study was consumed daily or over a duration of days or weeks.

If you found this article helpful, you'll enjoy Rain Organica's newsletter where more episodes and articles like this one are shared a couple times each month. 

Rain Organica offers simple, portable skincare products for the people who aren't really into skincare.

We treat skincare holistically, because a healthy you radiates the healthiest skin possible. 

If you're looking for more episodes like this, you may love these:



2 Fluoride Interactions with Iodine and Iodide:  Implications for Breast Health

3Orthoiodosupplementation: Iodine sufficiency of the whole human body

4Prevalence of autoimmune thyroiditis in patients with polycystic ovary syndrome

5Ovarian iodide uptake and triiodothyronine generation in follicular fluid: The enigma of the thyroid ovary interaction

6Iodine, Iodine metabolism and Iodine deficiency disorders revisited

7Importance of thyroid hormones for normal pregnancy

8Testicular Damage After Radioactive Iodine (I‐131) Therapy for Thyroid Cancer

9The Impact of Dietary Iodine Intake on Lipid Metabolism in Mice

10Fact Sheet for Health Professionals: Recommended Iodine Intake

11Iodine: Deficiency and Therapeutic Considerations

Other References (Iodine Specific)

Changes in Dietary Iodine Explains Increasing Incidence of Breast Cancer with Distant Involvement in Young Women

Optimum Levels of Iodine for Greatest Mental and Physical Health

Other References (Hashimoto's and Enlarged Lymph Nodes)

Hashimoto's Thyroiditis

The presentation of lymph nodes in Hashimoto’s thyroiditis on ultrasound

Shifting cervical lymphadenopathy in Hashimoto’s disease

Neck Lymph Nodes in Chronic Autoimmune Thyroiditis: The Sonographic Pattern







































Brandy Searcy founder Rain Organica

About the Author

Brandy's a formulation scientist and self-proclaimed health geek who loves hiking, gardening, bird-watching, and body boarding. 

Her struggle with acne during her teens and 20s led to a holistic and healthy approach to skincare, embracing skin as an organ to be loved and cared for rather than a canvas to wage war on. 

Since 2008, she's been developing all-in-one products for a simple routine at home, & Rain Organica started when her backpacking friends asked for a portable skincare routine to keep their skin healthy & happy on and off the trails.

You can try Rain Organica for yourself with The Essentials Kit, a complete skincare routine in just 3 steps.

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