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What Is Hashimoto’s Disease?

By 5th September 2022October 24th, 2022Health Conditions
Hashimoto's Disease

Hashimoto’s disease, also referred to as Hashimoto’s thyroiditis is a condition that impacts the function of the thyroid gland. This is the leading cause of hypothyroidism (an underactive thyroid) in iodine-sufficient areas of the world.

The cause of Hashimoto’s disease is thought to be due to a combination of 2 main factors. 

These are:

  • Genetics (our genes)
  • Environmental factors (such as diet and viruses)

These factors lead to what is described as loss of immune tolerance. This means that the body’s own immune system, which should normally be able to tolerate and not attack the thyroid gland, has lost the ability to tolerate the thyroid gland, views it as a potential threat, and attacks it. 

This autoimmune attack leads to thyroid damage, chronic inflammation and loss of thyroid function.  [Source: Pubmed]

Symptoms of Hashimoto’s disease?

The symptoms of Hashimoto’s are similar to what is seen in other conditions where the thyroid is underactive. 

These symptoms include:

  • Cool and dry skin
  • Constipation
  • Tiredness
  • Loss of body hair
  • Hoarse voice
  • Weight gain [Source: Pubmed]

However, while the symptoms may be similar the underlying cause of the symptoms of Hashimoto’s disease is different.

Blood tests will show an alteration in thyroid hormones. TSH (thyroid stimulating hormone)  becomes elevated while free thyroxine (FT4) is low. Additionally, the presence of elevated thyroid autoantibodies (TPOabs) is required for a diagnosis of Hashimoto’s.  [Source: Pubmed]

Also Read: Hashimoto’s Thyroiditis Symptoms

Symptoms of Hashimoto's Disease

Hashimoto’s and Gut Health

The hormones produced by the thyroid gland are required for energy production. This means that low levels of thyroid hormones can lead to impair energy levels throughout the entire body, including the gut.

This is why many people with Hashimoto’s thyroiditis can also experience gut symptoms such as IBS.  This is often due to slow transit time/constipation. Changes in the composition of bile can also lead to bile stone formation.  [Source: Pubmed]. This is reinforced in studies indicating a higher rate of removal of gallbladder removal in those with Hashimoto’s [Source: Pubmed].

Additionally, gut bacteria influence the levels of key nutrients required for thyroid health and thyroid hormone conversion. These include iron, iodine, copper, selenium, zinc and vitamin D. 

This connection between the gut and the thyroid is termed the thyroid-gut axis and has led to studies being carried out on the use of probiotic supplements to support thyroid health. [Source: Pubmed]

Also Read: Endometriosis and IBS – What’s the Connection?

Are probiotics good for Hashimoto’s?

Probiotics are described as non-pathogenic microorganisms that have a beneficial effect on the host. In hypothyroidism, low levels of key gut bacteria have been reported.

Studies have indicated that probiotics administration can help to improve many aspects of thyroid health. These include helping to balance levels of T4 and T3 and reducing levels of TSH. 

Some of these studies have been carried out in animals, however, human studies using probioitcs have resulted in a reduction in TSH levels as well as thyroid patients being able to reduce the dose of their thyroid medication. This indicated the beneficial impact on thyroid health simply by supporting the gut. [Source: Pubmed]

As mentioned, probiotics can positively impact levels of selenium, zinc and copper, all required for thyroid health.  It has also been found that gut microbes act as a store of T3 (the active form of thyroid hormone). This is another reason why a healthy gut can support the levels of thyroid hormones and potentially reduce the need for T4 medication.  [Source: Pubmed]

Do Hashimoto’s disease cause SIBO?

Imbalances in gut bacteria have also been noted in those with an underactive thyroid which can contribute to the ongoing gut issues in these patients.  SIBO (a bacterial overgrowth in the small intestine) has been found in more than 50% of those with an underactive thyroid. [Source: Pubmed]

Studies have indicated that dysbiosis (imbalances in the gut bacteria) can increase intestinal permeability (leaky gut) and lead to increased inflammation which can then impact thyroid function.  [Source: Pubmed]

Addressing SIBO and thyroid imbalance often needs to be addressed at the same time. This is due to gut issues and microbiome imbalances potentially impacting thyroid health while at the same time the thyroid imbalances impacting gut health.  This creates a feedback loop or vicious cycle. [Source: Pubmed]

What causes Hashimoto’s disease?

The onset of Hashimoto’s disease is understood to result from a combination of factors. This creates a situation that results in the loss of immune tolerance to the thyroid gland.


Epidemiological studies have observed an increased chance of Hashimoto’s disease if a family member also has the condition. One study indicated a 20-30% increased chance if a sibling has the condition.   In monozygotic twins, this ranges from 29% to 55%. [Source: Pubmed]

Iodine Intake

Iodine is an important mineral that is required for thyroid health. However, both low and high levels of iodine can have different impacts on the thyroid. 

In the parts of the world where iodine levels are sufficient, Hashimoto’s disease is the leading cause of an underactive thyroid.  However, an excessive level of iodine intake is linked with an increased rate of Hashimoto’s.  The opposite is also seen in areas where low iodine intake is linked with a lower rate of Hashimoto’s.  [Source: Pubmed]


Emotional stress impacts many areas of health which includes thyroid health. The link between stress and Hashimoto’s disease is likely due to the impact that cortisol (a hormone released when we are stressed) has on immune cells which can lead to immune dysregulation.  [Source: Pubmed]


Selenium is an essential trace mineral required for thyroid function. The thyroid contains the highest concentration of selenium in the human body.  Selenium supports the thyroid by acting as part of the antioxidant process which works to protect the thyroid gland.

Low levels of selenium are associated with immune dysfunction and reduced selenium intake is considered a risk factor for developing Hashimoto’s disease.  [Source: Pubmed]

Several studies have reported that selenium supplementation improves the levels of circulating thyroid antibodies, a marker of autoimmune activity. [Source: Pubmed]

Vitamin D

Vitamin D is a key nutrient for thyroid health and autoimmune activity. This can be due to the level of vitamin D but there can be genetic differences in the vitamin D receptors. This can prevent the vitamin D in the body from functioning optimally. These genetic variations have been indicated to be a risk factor in developing Hashimoto’s thyroiditis. 

Vitamin D has been studied and results indicate that vitamin D levels are lower in those patients with Hashimoto’s thyroiditis than in those without. This study also reported that supplementation with vitamin D helped to improve thyroid health in Hashimoto’s thyroiditis. [Source: Pubmed]

Does Hashimoto’s lead to other autoimmune conditions?

If a patient has an autoimmune condition, such as Hashimoto’s thyroiditis, it is likely another may coexist. This means that a syndrome known as polyglandular autoimmune syndrome (PAS) may occur.  This is where the autoimmune process also impacts other glands within the body.

The conditions can include:

  • Addison’s disease
  • Hypogonadism
  • Vitiligo
  • Alopecia
  • Pernicious anaemia
  • Type 1 diabetes

In most cases, the onset of PAS was the presentation of type 1 diabetes and autoimmune thyroid disease.  This was noted in 48% of cases. This is likely due to a similar genetic susceptibility in both type 1 diabetes and autoimmune thyroid diseases. [Source: Pubmed]

Best foods for Thyroid health

As discussed, key nutrients are required for thyroid health. These can be found in their natural form from food.

  • Iron – liver, red meat, beans (such as red kidney beans, edamame beans and chickpeas), nuts, dried fruit – such as dried apricots.
  • Iodine – Seaweed (nori, kelp, kombu, wakame), fish, shellfish (cod, canned tuna, oysters, shrimp), dairy (milk, cheese, yoghurt), eggs, beef liver, chicken.
  • Copper – liver, oysters, spirulina, nuts and seeds, lobster, leafy greens.
  • Selenium – pork, beef, turkey, chicken, fish, shellfish, eggs, Brazil nuts.
  • Zinc – oysters, red meat, poultry, beans, nuts, crab and lobster.

It may also be beneficial for some of these nutrients to be taken in the form of supplements. Working with a registered practitioner can help guide the appropriate doses of these.

Also Read: Low FODMAP Foods – Everything You Need To Know


It is true that thyroid health can impact gut health.  It is also the case that gut health can impact thyroid health. Working to address and approach both of these areas is important when aiming to restore health.

Working with a Registered Nutritional Therapist can guide and support you through this process.