Why Iodine Is One Of The Most Crucial Supplements For Women’s Health

Iodine drop in water. Via: Jasenka Luksa | Shutterstock.


by Dr. Lara Briden

on March 23, 2016

Why I Prescribe Iodine For Breast Pain, Ovarian Cysts, And PMS

I consider iodine one of the most important supplements for women’s health (just behind magnesium, vitamin D, and zinc).

I prescribe iodine for breast pain, ovarian cysts, ovulation pain, and PMS, and I prescribe it even when there is no thyroid problem. In fact, I am more cautious when there is a thyroid problem (because iodine can damage the thyroid gland).

Via: Mikael Häggström

Via: Mikael Häggström

Benefits Beyond Thyroid

Iodine is not just for thyroid. Many tissues need it including brain, immune system, prostate gland, ovaries, uterus, and breasts. More than 70 percent of the body’s iodine is concentrated in those tissues — and not in the thyroid gland or thyroid hormone. It’s there because it’s an important antioxidant, and because it plays a key role in immune function, detoxification, and mitochondria regulation.

Iodine also affects ovulation and estrogen.

Iodine Promotes Ovulation

The ovaries contain more iodine than any other organ except the thyroid. Researchers don’t yet exactly know what it is doing there, but it does seem to promote healthy ovulation.

Iodine reduces ovulation pain, prevents ovarian cysts, and boosts progesterone (because ovulation is how you make progesterone). Read “Road Map to Progesterone.”

Iodine Is Anti-Estrogen

It reduces estrogen in two ways.

That’s why iodine is one of the most important treatments for estrogen excess/estrogen dominant symptoms such as breast pain, ovarian cysts, and PMS.

35pix_26a0 copyTip: Iodine alone is not sufficient treatment for PMS. Additional treatments include anti-inflammatory diet (possibly low-histamine diet), magnesium, and vitamin B6. Read “The PMS Solution.”

Conditions That Benefit From Iodine

You need some iodine for these conditions, even if you have thyroid disease (Hashimoto’s), or even over-active thyroid (hyperthyroidism). I don’t agree that thyroid disease means you must avoid all iodine. You just must be careful. Stay at a low dose such as 500 mcg (0.5 mg) to begin. Talk to your doctor.

35pix_26a0 copyTip: Ovarian cysts refers to abnormally large cysts or true cysts. The multiple small follicles of polycystic ovarian syndrome are not cysts. Read “The Surprising Truth About PCOS.”

Seaweed such as wakame (pictured) is a natural source of iodine. Via: えむかと | Public domain.

Edible seaweed such as wakame (pictured) is a natural source of iodine. Via: えむかと | Public domain.

Best Forms Of Iodine

There are three main forms for supplementation: potassium iodide (KI), molecular iodine (I2), and seaweed which contains a mix of KI, I2, and iodate (IO3-).

Compared to iodide, molecular iodine is absorbed at a faster rate into breast tissue and a slower rate into thyroid. That makes I2 a better form for women’s health, and a safer form for the thyroid (less likely to cause thyroid problems). Unfortunately, I have not yet been able to locate a low dose I2 supplement, so I usually still prescribe potassium iodide. Popular products such as Lugol’s solution provide a combination of high-dose I2 and potassium iodide.

What Dose?

There is no topic in natural medicine more controversial than the dosing of iodine.

On the one hand, conventional medicine is very conservative. The RDA is 150 mcg (0.15 mg) with an upper tolerable limit of 1,100 mcg (1.1 mg). Thyroid experts argue that doses greater than 500 mcg (0.5 mg) can trigger autoimmune thyroid disease, and doses greater than 225 mcg (0.25 mg) are not safe for pregnant women.

On the other hand, practitioners like David Brownstein advocate for mega-doses up to 50,000 mcg (50 mg) per day. That is 100 times (10,000 percent) greater than what your doctor considers safe.

I agree that the RDA of 150 mcg is far too low. It prevents goiter (enlarged thyroid) but is not enough for ovaries and breasts. At the same time, I am not convinced that mega-dosing is safe. It can suppress thyroid function and trigger autoimmune thyroid disease. Read “Megadose iodine: an idea whose time has gone.” Even the Japanese, who are the world’s highest iodine consumers, do not consume more than 5280 mcg (5.2 mg) as part of their daily diet.

I usually prescribe in the 500 – 5000 mcg (0.5 – 5 mg) range , but only after first testing for thyroid autoimmunity (see below).


Random “urinary iodine” is the most common test. It’s not a perfect test, and is primarily recommended for population studies — not individual assessment. Read Controversies in urinary iodine determinations. Deficiency is defined as less than 100 mcg/L (after adjustment for creatinine). To make the test more reliable, I ask my patients to test in the morning, and to avoid iodine-containing supplements, foods, or thyroid medication for 24 hours prior.

24 hour urine test is more accurate, but is still not perfect and is a chore to do.

There is something called an iodine challenge test but I don’t trust its accuracy. Also it involves giving a single dose of 50,000 mcg (50 mg) to a patient, which I would never do until I had first tested for thyroid antibodies.

Thyroid antibodies (thyroid autoantibodies, anti-thyroid antibodies, anti-TPO antibodies) is the single most important test to do before supplementing. It is a marker of latent autoimmune thyroid disease, and can predict if supplementation is likely to trigger full-blown thyroid disease (Hashimoto’s). You can still take some iodine with autoimmune thyroid disease (remember, you need it for your breasts and ovaries!), but you must start at a low dose like 250 mcg (0.25 mg) and work up slowly.

Breast tenderness is a reliable symptom of deficiency. I find it more useful than any test.

Who Is Most At Risk Of Deficiency?


The mineral selenium protects the thyroid from damage and over-stimulation by iodine. I usually recommend 100 mcg selenium.

Food Sources

Content of food varies greatly, which is why I prefer to use a supplement in most cases.

  • Seafood (10 – 190 mcg per 100 grams).
  • Seaweed (2 – 800 mcg per 100 grams). Unfortunately, seaweed also contains bromine, which prevents the uptake of iodine, and may contain toxic metals.
  • Grass-fed butter, but only if it’s grown on rich soil.
  • Iodized salt (400 mcg per teaspoon).
  • Plant foods such as mushrooms and leafy greens, but only if they’re grown on rich soil.

Final Word

I love iodine for women’s health. That’s why I include it as one of the top 5 nutrients for period health in my book Period Repair Manual.

What do you think? Do you take it or prescribe it?

Yours in Health,




Natural health evangelist, hormone expert, and author of Period Repair Manual, Lara Briden first worked as an evolutionary biologist at the University of Calgary. She went on to graduate as a naturopathic doctor from the Canadian College of Naturopathic Medicine (CCNM) in Toronto. Her love of science and the natural world has informed the way she practices medicine. During her nearly twenty years of practice, thousands of patients have entrusted her with their hormone stories. She shares what she’s learned at larabriden.com.