The Link Between Your Gut Microbiome and Thyroid Hormones

Posted October 2022
Avocado wedges, grilled corn, Caesar dressing & chilli on Corn Thins slices

Your body requires a matrix of systems working effectively for optimal health and function. One of these systems is your endocrine system. This system consists of organs and glands which produce hormones. Hormones are chemical messages which influence the health and function of your body. One of the organs of the endocrine system which creates and regulates hormones in your body is your thyroid. If you are unfamiliar with your thyroid, it is a butterfly shaped organ located at the base of your neck.

Your thyroid is an organ you want working optimally. One primary role your thyroid has is regulating your rate of metabolism which plays a huge role in achieving and maintaining a healthy weight. It may surprise you to hear that your gut microbiome assists in converting twenty percent of the inactive thyroid hormone called thyroxine (T4) into the active thyroid hormone called triiodothyronine (T3).

T3 plays many important roles including regulating your body temperature, influences your metabolic rate, influencing your weight, the health of your skin and hair, just to name a few important functions. T3 also heavily influences the permeability of the tight junctions on your small intestine and stomach. This effects the level of permeability of your intestinal wall. There is a delicate balance of optimal permeability in your gut wall. Compounds need to be able to move in and out such as fluids and nutrients. On the other hand, your gut wall needs to be able to block out toxins and microorganisms as part of the immune system defence.

If the permeability of your intestinal wall is out of balance this can lead to a chronic inflammatory state in your body as well as a suboptimal immune system function. This imbalance may also increase your risk of developing chronic diseases and autoimmune diseases such as Hashimoto’s thyroiditis, and Grave’s disease.

To maintain the health promoting microbes which assist in the conversion of thyroxine hormone triiodothyronine it is essential to achieve your daily dietary fibre needs. Health promoting microbes consume a type of fibre called prebiotic fibre. There are different prebiotic fibre types in different plant foods which is why including a variety of different plant-based foods to meet your dietary fibre needs is important.  Plants also are a source of other types of fuel for the health promoting microbes in your gut called polyphenols.

You are not alone if you do not think you are getting enough dietary fibre each day. It is estimated more than fifty percent of children, and more than seventy percent of adults are not meeting their recommended dietary fibre targets each day.

An adult requires between 25-38 grams of dietary fibre each day. Plant foods which are rich in dietary fibre include whole grains, or whole grain containing foods like Corn Thins slices, fruits, vegetables, legumes, beans, nuts, and seeds. By including half of each meal and snacks as produce and including more plant sources of protein you can achieve this daily target.

Take home message: Your gut is a key driver to many aspects of your health and wellbeing. Another reason to look after your gut microbiome which you may not have considered is to allow the thyroid hormones to work effectively in your body.




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Ashleigh Felth…
Accredited Practising Dietitian
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    • Ashleigh Felth…