How does your gut microbiome influence thyroid function?

The thyroid-gut axis refers to the bidirectional communication and interaction between the gut microbiome and the thyroid gland. While research in this area is still ongoing, there is evidence to suggest that the gut microbiome can influence thyroid function through various mechanisms. Let's look at what these are...


Immune modulation

The gut is a major site of interaction between the immune system and your gut microbiome. Dysbiosis, an imbalance in the gut microbiota composition, can lead to immune system dysfunction and inflammation. This chronic inflammation may affect the thyroid gland and contribute to autoimmune thyroid diseases like Hashimoto's thyroiditis and Graves' disease.

Nutrient absorption

The gut is responsible for absorbing essential nutrients, including iodine and selenium, which are crucial for thyroid hormone synthesis. A poor digestive function can impair nutrient absorption, potentially leading to thyroid dysfunction due to deficiencies in these key elements and others, such as iron.

Thyroid hormone metabolism

Deiodinase activity has also been found in the intestinal wall and could contribute to total T3 body levels, affecting thyroid function.

Gut permeability

Increased gut permeability (leaky gut) can allow substances associated with poorer health outcomes to enter the bloodstream, potentially triggering low-grade chronic inflammation that may affect thyroid function and other areas of your health.

Chronic constipation

Constipation can be uncomfortable and lead to stress or anxiety. Stress can affect the hypothalamus-pituitary-thyroid (HPT) axis, which controls thyroid hormone production and release. Dysregulation of this axis can influence thyroid function.

Research into the thyroid-gut axis is still evolving, and many details remain to be elucidated, however, a lot can be done to support your thyroid function by supporting your digestive and microbiome health. 

How to support your thyroid function

Maintaining a healthy gut microbiome through a balanced diet rich in fibre, the correct choice of probiotics, and prebiotics, as well as avoiding factors that disrupt gut health (such as foods that are highly processed), may be beneficial for overall thyroid health. Eating foods rich in Iodine can also help support thyroid function.

By making dietary changes focused on gut health, you can simultaneously improve how well your thyroid gland functions. The gut-brain axis serves as a vital link, and nurturing this connection through a diet that is right for you helps create an environment that supports your thyroid.

When I see clients, I often discuss and recommend specialised functional testing, including digestion function and microbiome testing as it can help you identify whether you are likely to have gut microbiomes that may be contributing to inflammation or not.

In addition, I can help you identify if you have any nutrient deficiencies via analysis of your diet or specific laboratory testing. I often see better results more quickly by adopting a more holistic approach that incorporates, diet, lifestyle and targeted supplements based on your unique profile which can be accessed via functional testing.

To find out more about how I can help you, please schedule a complimentary call today.


Knezevic, J Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function? Nutrients. 2020 Jun; 12(6): 1769.doi: 10.3390/nu12061769

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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London SW15 & W1H
Written by Melody Mackeown, mBANT, CNHC, BSEM | Nutritional Therapist and Health Coach
London SW15 & W1H

Melody Mackeown is a Nutritional Therapist who works across the UK and worldwide.

If you are looking to work with an expert who can help you figure out the best foods for you without the guesswork or faddy diets you are in the right place. Together, we can help figure out the root cause of your digestive problems and find effective solutions.

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