The thyroid is the body’s engine

Thyroid health seems to be an issue more for women than men – although it can affect both. We may not have the obvious symptoms of over or under active thyroid but the thyroid can be flailing long before symptoms are thrown up. 

Some of the symptoms of low thyroid are fatigue, muscle weakness, hair loss, high cholesterol, weight gain, mood swings, cold extremities, depression, insomnia, irritability, premature greying of the hour, infertility, dry scaly skin,

Thyroid function 

The thyroid is a critical gland which plays an essential role in the metabolism, so slow/sluggish thyroid will translate in to slow processes throughout the body such as digestion, growth, glucose metabolism. We have thyroid receptors in every cell of the body – so when the thyroid slows down, WE slow down.

The thyroid gland has many functions – it promotes normal brain function, protein synthesis, growth and development, break down of fats in the body (lipolysis), increases metabolic rate to help the body convert food in to energy, converts beta carotene from our food in to vitamin A. It also influences the liver, gallbladder, brain, muscles and heart. And thyroid hormones help to strengthen hair, nails and skin. So it’s no surprise that every single cell in the body has thyroid receptors.

This tiny, butterfly shaped gland that sits in the neck has a huge impact on pretty much every aspect of our health.

Thyroid Pathway

The thyroid is responsible for making the hormone thyroxine. It produces thyroxine in its INACTIVE form (T4). 

Then it sends it to the liver to be converted to the ACTIVE form T3. However there are many factors that affect this conversion – liver health being the obvious one, and I will discuss the others below. 

When this conversion from T4 to T3 doesn’t take place efficiently, then the T4 can instead be converted to reverse T3. Reverse T3 can create cellular resistance to T3.

Impact of Stress

Stress plays an important role in the functioning of the thyroid gland. When the body is in fight/flight – or sympathetic nervous system mode, this affects the HPT axis whereby the hypolthalamus sends a message to the pituitary gland by releasing TRH (thyroid releasing hormone), and then the pituitary gland releases TSH (thyroid stimulating hormone), which tells the thyroid to produce T4 to be converted to T3 in the liver. 

Stress acts on the pathway between the pituitary and the thyroid and so will interfere with the message reaching the thyroid to stimulate it to produce T4. 


Many nutrients are required for thyroxine synthesis. For example, L tyrosine is an amino acid needed to produce T4, which is why protein is so important in the diet, along with iodine, selenium and manganese. Also Vitamins A, B2, B6, B12 and C, as well as iron are required to get iodine into the thyroid gland.

Lack of essential fatty acids, too many trans and hydrogenated fats, lack of vitamin A and D, and zinc, will all impact and adversely affect the body’s ability to convert the T4 in to T3 (active form of thyroxine). Gluten should also be avoided due to its molecular mimicry to the thyroid tissue. 

Selenium, and a healthy liver, gall bladder and kidneys are also required to make this conversion since the liver is where the T4 is converted to T3 and these organs are all connected and work together.

Getting our gut bacteria in balance will also be helpful. Around 20% of thyroid function depends on having the right amount of beneficial bacteria in our gut microbiome. So think about introducing some fermented foods or yoghurts, or a well balanced probiotic supplement if indicated.

Just to complicate things further, the T4 that is made by the thyroid can either be converted to T3 (active form which the body requires) but also can sometimes be converted to reverse T3 which is inactive and can’t be used by the body. And the chances of the T4 being converted to the inactive reverse T3 are increased by high levels of cortisol (stress), oestrogen deficiency, ferritin deficiency, low selenium.

Stress is an issue here too, because when we are stressed, we have more adrenaline and cortisol in the body and this will impact the thyroxine pathway in that it will make the T4 actually convert to reverse T3 instead of active T3.

So it’s clear that hypothyroidism is a multi factorial condition which isn’t only dependent on nutrition – it will incorporate lifestyle changes too. The other factors that will increase conversion of T4 to reverse T3 instead of active T3 are trauma, low calorie diets, inflammation, toxins, infections, liver and kidney stress and a high sugar diet.

Additionally, the thyroid regulates calcium, so when calcium is very high it would usually indicate that the thyroid isn’t doing its job properly. If the thyroid is under functioning then it won’t produce calcitonin which is what regulates calcium, and then a calcium shell may be forming. We can see levels of calcium and thyroid function by performing a Hair Tissue Mineral Analysis which will also look at heavy metal excretion, mineral status in soft tissues as well as adrenal function, blood sugar and hormone balance. See more information here 

A full blood thyroid panel test will include the markers free T4 and T3, as well as reverse T3, TSH (thyroid stimulating hormone), and thyroglobulin antibodies. In this way we can can see where along the pathway the problem lies. Rather than simply taking synthetic thyroxine supplements (which are the inactive T4 and still need to be converted by the liver to active T3!) since thyroxine production is clearly only one part of a multifaceted issue. 

Working with a nutritional therapist means that you can address your liver function, hormone balance, nutrient deficiencies, lifestyle and gut health which are all necessary in supporting the thyroid. 

Please be in touch here if you’d like to work with me on this or anything else.