Oestrogen, Iodine and Thyroid. You may be wondering what do these three things have to do with each other? Well, they are connected and influence each other in many ways!

Here I hope to be able to make the connection for you and see how your menstrual cycle can be affected. Especially when entering menopause when your reproductive hormones take on a life of their own.

In this blog, I’ll look at how oestrogen, iodine and thyroid interact, what can interfere with this process and what some of the signs and symptoms may be.


How do Iodine, Oestrogen and Thyroid interact?

To begin with, oestrogen receptors are not found solely in the uterus and ovaries. They are found in many areas throughout your body. Many are found in your brain, along with the heart, breast, adipose tissue and thyroid.

As you would now be aware (after reading my blog on Histamine – PMS & Anxiety) oestrogen not only regulates your menstrual cycle, preparing your uterus for conception. It also works with histamine, which helps to promote vasodilation, increasing blood flow to the uterus, etc.  When everything is balanced, all is working as it should.



The oestrogen receptors within the various area of the brain (in particular) are : 

  • Limbic area – contains the amygdala, hippocampus, hypothalamus, pituitary gland. This area controls emotion, smell, long term memory, behaviour and the endocrine system; it responds to stress and when in ‘fight or flight mode’
  • Prefrontal cortex – the centre for emotional processing, rational thinking, decision making.
  • Brain stem – main control centre for your whole body; in particular breathing, heart rate, blood pressure, being asleep/awake
  • Cerebellum – controls your voluntary movements related to balance, speech, posture and coordination
  • Dorsal raphe nucleus also affects emotion, memory and, learning.

Within these areas, the oestrogen receptors stimulate the release of serotonin, dopamine. They also activate the glutamate and GABA pathways.  Here you will also find progesterone receptors which can counteract the effect of oestrogen, as all is in balance.

When hormones are out of balance

When levels are too high or low, it will have an obvious effect on you. It will also reduce your progesterone levels, having a flow on effect on how it works within your body. This is where you may experience –

  • being anxious
  • poor memory retention
  • emotional (weepy, angry, sad)
  • mood fluctuations
  • lack of motivation
  • increased heart rate and blood pressure
  • sleepy
  • poor concentration
  • agitated
  • impulsive
  • aggressive
  • binge eating
  • loss of periods due to inhibition of ovulation
  • heavy bleeding
  • PMS
  • food sensitivities may begin to develop
  • impaired thyroid function



Iodine is needed to help make your thyroid hormones – T4, T3. You also need Tyrosine and, its cofactors of Selenium, Zinc, Vitamin C, Riboflavin, Niacin, pyridoxine, Chromium, Copper, Folate; which are involved in other biochemical processes to make the hormones.  

Iodine helps to break the interaction between your mast cells and oestrogen, stopping the release of histamine. It interrupts this cycle which can be on overdrive if there is too much of one or the other. It also supports dopamine’s action by stabilising your mast cells. That is, they are not activated to release histamine. And it also helps to stimulate the release of DAO (Diamine Oxidase), which naturally helps break down histamine that is either produced by your body, or you ingest from foods.

As well as interrupting the oestrogen-histamine-mast cell cycle, Iodine also helps you to maintain oestrogen levels, in particular the form of estriol (Head K. A, 1998). This is a weaker form of oestrogen produced by your body, and it gives you other health protecting benefits.



Your thyroid needs several nutrients to make T4, T3. It also needs the hormones Thyroid Stimulating Hormone (TSH) and Thyrotropin Releasing Hormone (TRH), to either stimulate it to make more T3 & T4 or, to reduce production. Iodine is one of the nutrients that most of you are aware of. But did you know that you also need the following cofactors of:

  • Selenium
  • Magnesium
  • Zinc
  • Vitamin C
  • Riboflavin
  • Tyrosine

Cells throughout your body need and use T3 & T4 for:

  • Metabolism
  • Cell energy production
  • Cellular repair
  • Protect and insulate nerve cells, and support activity
  • Regulation of other hormones and cellular activity


Signs of low hormone levels

So, if you’re not producing enough of these hormones then you can experience some, or all, of the following –

  • Low energy
  • ‘Foggy mind’
  • Anxiety
  • Depression
  • Poor breakdown of carbohydrates. This can lead to weight gain, insulin resistance, disruption of hunger signals
  • Loss of menstruation, or heavier menstruation
  • Impaired liver function – affecting clearance of oestrogen and its by-products

These are just some of the signs and symptoms that you may experience.

If your cells aren’t able to effectively produce and make energy, it will eventually lead to insulin resistance. This, over time, leads to weight gain and more adipose fat. Eventually, these two factors will have an impact on other processes within your body. In some instances, putting in motion several vicious cycles; as all processes are interconnected within your body.

Also, high oestrogen levels can trigger your liver to release thyroid-binding globulin (TBG). What this does is bind free thyroid hormones that are circulating in your blood, reducing the amount available for your thyroid to use.

Here I have given you a rough overview of what Oestrogen, Iodine and Thyroid do, individually and as a group. I hope that this gives you an idea of the work that these three things do. Next month I’ll look at what can interrupt this function and, what you can do to support this and, hopefully, prevent other issues from arising.

To know what is happening exactly, there are tests that you need to do. One of them being HTMA. I am here to help you if you need assistance with your hormones and health.



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