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).
Iodine’s 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 it’s one of the most important treatments for estrogen excess/estrogen dominant symptoms such as breast pain, ovarian cysts, and PMS.
Conditions that benefit from iodine
- Fibrocystic breasts, breast cysts, and pain
- Breast cancer prevention
- Ovarian cysts and pain
- Anovulation (failure to ovulate) and irregular periods including some types of PCOS
- Heavy periods
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.
⚠️ Tip: 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.
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.
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.
A 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 iodine deficiency?
- Women 40-49 (also the most at risk for estrogen excess and breast cancer)
- Pregnant women
The mineral selenium protects the thyroid from damage and over-stimulation by iodine. I usually recommend 100 mcg selenium.
The 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.
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,