Probiotics for Thyroid Health

Your body is a home to many types of bacteria. The word “bacteria” is associated with danger, disease, virus, and other negative things, but it doesn’t have to be like that.

You see, we can divide bacteria in the body into two groups: good and bad.

Balance of both of them is vital for strong immune system and optimal health.

Probiotics belong to the first group, good ones, and they are thought to be extremely beneficial for our overall wellbeing.

But, can they help thyroid problems, such as Hashimoto’s?

What are probiotics?

Probiotics are defined as live microorganisms with various health benefits.

Despite the recent spike in popularity, the idea of probiotics has been investigated for a long time.

About a century ago, Henry Tissier of the Pasteur Institute isolated bacteria now called Bifidobacterium bifidum from the feces of healthy breastfed infants which were absent in guts of formula-fed infants with diarrhea.

The discovery led to a conclusion that these bacteria exhibit positive effects on our health[i].

Tissier’s discovery paved the way for a number of studies on probiotics which have now become a popular way to maintain health and improve digestion.

The term probiotic derives from the Greek and means “for life” and it was initially used to describe substances produced by one microorganism that stimulated the growth of others.

Only later, when more studies came along, probiotics got the meaning we know today.

Benefits of probiotics are numerous, including:

  • Improvement of intestinal health
  • Enhancement of the immune response
  • Reduction of serum cholesterol
  • Cancer prevention
  • Improvement of lactose metabolism
  • Protection against allergies
  • Prevention of coronary heart disease
  • Blood pressure control

Does support to thyroid health and function belong to the group of the above-listed benefits of probiotics?

Find the answers below.

Thyroid and Hashimoto’s thyroiditis

The reality is that the connection between probiotics and thyroid health and function isn’t studied enough as it should be. At this point, evidence on this subject is reduced to a minimum, but it’s not nonexistent.

When it comes to thyroid and probiotics, the influence of these good bacteria on Hashimoto’s thyroiditis is discussed the most.

Hashimoto’s thyroiditis is an autoimmune disease meaning the body’s immune system attacks the thyroid and impairs its function. This autoimmune disease is a major cause of hypothyroidism.

The exact cause of autoimmune conditions is still unknown, and it is highly likely that a combination of different factors plays a role.

Gut microbiota triggers Hashimoto’s

Mori et al report that the intestinal mucosa constantly comes across numerous “antigens derived from commensal organisms, food, and occasional pathogens.”

Our immune system works “to balance between tolerance against commensal bacteria, dietary antigens, and protective reactions against harmful pathogens in order to maintain homeostasis.”

“Indigenous bacteria in our gut contribute to the formation of barrier against invasive pathogens.” At the same time, “products of the bacterial fermentation of undigested fibers in the intestine” inhibit pro-inflammatory cytokines. Any kind of dysbiosis, microbial imbalance, disturbs the finely tuned immune balance and could “lead to the development of autoimmune disorders.”

Disrupted mucosal barrier allows exposure of submucosal immune cells to bacterial and dietary antigens, thus causing an unfavorable immune activation and formation of autoimmune diseases. Changes such as increased intestinal permeability, intraepithelial lymphocyte infiltration have been found in patients with type 1 diabetes, but they have been also observed in Hashimoto’s thyroiditis patients[ii].

February 2018 issue of the journal Thyroid published a study conducted by Zhao F. et al. What makes this study important is the fact it is the very first research to investigate the relationship between Hashimoto’s and gut microbiota directly.

The cross-sectional study enrolled 28 patients with Hashimoto’s thyroiditis and 16 healthy controls. Scientists collected fecal samples and used 16S ribosomal RNA gene sequencing to analyze microbiota. To evaluate the diagnostic potential of the selected biomarkers, independent cohort involving 22 Hashimoto’s thyroiditis patients and 11 healthy controls was used.

Results showed that HT patients exhibit a distinct gut microbiota than healthy controls and they confirmed that dysbiosis of gut microbiota plays a role in the formation of this autoimmune disease.

What’s more, the study revealed that HT patients have greater gut microbiota diversity than healthy controls, but the balance of good and bad bacteria is different. HT patients have a higher concentration of Firmicutes, a phylum of gram-positive bacteria, but some strains can be gram-negative.

Firmicutes account for the largest portion of mouse and human gut microbiota and some strains are involved in energy resorption, potentially related to obesity and diabetes. On the other hand, the concentration of Bacteriodetes was less abundant.

Bacteriodetes are usually gram-negative bacteria.

Patients with Hashimoto’s thyroiditis have an impaired F/B bacteria ratio compared to healthy controls[iii], the study found.

Probiotics balance gut microbiota

As mentioned above, probiotics are vital for proper gut microbiota balance. Hemarajeta and Versalovic report probiotics produce antimicrobial agents or metabolic compounds whose primary function is to suppress the growth of other microorganisms or compete for receptors and binding sites with other intestinal microbes.

One of the most potent probiotic strains, Lactobacillus family, enhances the integrity of the intestinal barrier in order to promote immune tolerance. In addition, probiotics have the ability to modulate the intestinal immunity and alter the responsiveness of the immune cells and intestinal epithelia to microbes in the intestinal lumen (opening inside a tubular body structure like large and small intestine).

Probiotics exhibit immunomodulation effects too. For instance, L. reuteri strain regulates cytokine production by human immune cells and it can induce production of anti-inflammatory cytokines which strengthen the immune system and fight inflammation[iv].

Bearing in mind that imbalance in gut microbiota triggers Hashimoto’s thyroiditis and probiotics support healthy gut microbiota balance, their benefits for HT patients seem highly likely.

More research on this subject is necessary to uncover the exact relationship between Hashimoto’s and probiotics as well as their impact on overall thyroid function.

Probiotics and hypothyroidism

Hypothyroidism is a common condition indicated by an underactive thyroid gland i.e. insufficient production of thyroid hormones.
A wide array of causes can lead to hypothyroidism including autoimmune condition Hashimoto’s, but also a treatment for hyperthyroidism, medications, thyroid surgery, and others.

Many hypothyroid patients are using or consider using probiotics to help manage their condition, but it’s not just a trend – probiotics can help indeed.

Bacterial overgrowth in hypothyroidism

Small intestinal bacterial overgrowth (SIBO) is the presence of excessive bacteria in the small intestine and it is frequently associated with malabsorption and diarrhea[v].

Patil A. reports that SIBO is present in more than a half of patients with hypothyroidism although hypothyroid patients are more likely to have constipation than diarrhea.

Gastrointestinal hypomotility associated with hypothyroidism tends to promote bacterial overgrowth and leads to chronic GI symptoms. Unfortunately, these symptoms are usually ignored in hypothyroid patients due to systematic signs and symptoms involving cardiovascular, neuromuscular, and other systems.

Since hypothyroid patients experience disturbed GI motility they are also prone to SIBO[vi] and it is important for patients to consult their doctors about it.

A growing body of evidence confirms that probiotics are effective in the management of SIBO. Khalighi et al carried out a study of 30 people and discovered that adding lactol probiotic to the maintenance therapy of SIBO patients is beneficial for prevention of complications associated with this condition[vii].

Probiotics prevent hormone fluctuations

An interesting study was published in the Frontiers in Endocrinology in November 2017. Spaggiari et al investigated whether a mixture of highly charged Lactobacilli and Bifidobacteria can influence the metabolism of LT4 (levothyroxine) acting on gut microbiota. They enrolled 39 hypothyroid patients and 41 healthy controls into their study. Results showed that intake of a probiotic mixture doesn’t alter LT4 therapy.

Probiotics-induced modification of intestinal bacteria doesn’t affect LT4 absorption when probiotics are administered at least 2h after the hormone intake. These findings led to a conclusion that concomitant intake of probiotics could enhance the stability in thyroid function compensation. As a result, modified and improved gut microbiota increases the bioavailability of LT4.

Interestingly, the study also revealed that probiotics can influence the metabolism of thyroid hormones although the final and significant difference in hormonal levels wasn’t detected. Scientists speculate long-term treatment i.e. use of probiotic mixture could be more effective (the study was carried out over 2 month treatment period and 2 months of follow-up).

Basically, scientists discovered that probiotics contribute to thyroid hormone homeostasis and stabilize LT4 treatment, and prevent hormonal fluctuations in hypothyroid patients[viii].

Weight management

Patients with thyroid problems, particularly hypothyroidism, tend to gain weight and find it difficult to slim down. Many people take probiotics supplements or foods that contain them in order to lose weight.

While this may seem like a myth, a growing body of evidence confirms this important effect of probiotic intake.

Ogawa et al found that Lactobacillus gasseri SBT2055 inhibits the absorption of dietary fat, thus increasing the amount of fat that is excreted from the body with feces[ix]. Basically, probiotics make you harvest a lower amount of calories from food.

Moreover, Yadav et al discovered that certain probiotics release the GLP-1, the satiety or appetite-reducing hormone[x]. Elevated levels of this hormone help you burn more fat and calories.

In their study, Omar J. et al found that consumption of yogurt with Lactobacillus amylovorus or Lactobacillus fermentum decreased body fat by 3% to 4% over a six-week period[xi]. On the other hand, Sanchez et al studied 125 overweight dieters to investigate the effects of Lactobacillus rhamnosus supplementation on weight loss. They found these good bacteria contributed to weight loss and reduction of body fat mass[xii].

Sources of probiotics

Health benefits of probiotics are numerous and although their influence on thyroid function isn’t studied enough, the relationship between the two is evident. As a result, probiotics could be useful for patients with thyroid disorders.

Finding a supplement is easy, but you should still consult your doctor to make sure you’re making a great decision.

Probiotics are also present in different foods, such as:

  • Kefir – a fermented probiotic milk drink
  • Kimchi – spicy and fermented Korean dish
  • Kombucha – fermented green or black tea drink
  • Miso – seasoning
  • Pickles – chances are you already have them in the fridge
  • Sauerkraut – finely shredded cabbage that has been fermented by lactic acid bacteria
  • Tempeh – fermented soybean product
  • Yogurt – probably the most well-known source of probiotics, but when buying a yogurt strive to choose plain varieties


What goes on in your gut influences your entire health and wellbeing.

That said, gut health depends on the balance of good and bad bacteria.

Probiotics are good microorganisms that improve the immune system, exhibit anti-inflammatory effects, improve digestive health, aid weight management, and so much more.

At this point, studies about their influence on thyroid disorders are insufficient, but the relationship is obvious.

Patients can benefit from intake of probiotics via food or supplements, but consulting a doctor is always recommended.


[i] Kechagia M, Basoulis D, Konstantopoulou S, et al. Health benefits of probiotics: a review. ISRN Nutrition 2013;2013:481651. doi:10.5402/2013/481651.

[ii] Mori K, Nakagawa Y, Ozaki H. Does the gut microbiota trigger Hashimoto’s thyroiditis? Discovery Medicine 2012 Nov;14(78):321-6.

[iii] Zhao Fuya, Feng Jing, Li Jun, Zhao Lei, Liu Yang, Chen Huinan, Jin Ye, Zhu Biqiang, and Wei Yunwei. Thyroid. February 2018, 28(2): 175-186. Doi: 10.1089/thy.2017.0395

[iv] Hemarajata P, Versalovic J. Effects of probiotics on gut microbiota: mechanisms of intestinal immunomodulation and neuromodulation. Therapeutic Advances in Gastroenterology. 2013;6(1):39-51. doi:10.1177/1756283X12459294.

[v] Dukowicz AC, Lacy BE, Levine GM. Small Intestinal Bacterial Overgrowth: A Comprehensive Review. Gastroenterology & Hepatology. 2007;3(2):112-122.

[vi] Patil AD. Link between hypothyroidism and small intestinal bacterial overgrowth. Indian Journal of Endocrinology and Metabolism. 2014;18(3):307-309. doi:10.4103/2230-8210.131155.

[vii] Khalighi AR, Khalighi MR, Behdani R, et al. Evaluating the efficacy of probiotic on treatment in patients with small intestinal bacterial overgrowth (SIBO) – A pilot study. The Indian Journal of Medical Research. 2014;140(5):604-608.

[viii] Spaggiari G, Brigante G, De Vincentis S, et al. Probiotics Ingestion Does Not Directly Affect Thyroid Hormonal Parameters in Hypothyroid Patients on Levothyroxine Treatment. Frontiers in Endocrinology. 2017;8:316. doi:10.3389/fendo.2017.00316.

[ix] Ogawa A, Kobayashi T, Sakai F, et al. Lactobacillus gasseri SBT2055 suppresses fatty acid release through enlargement of fat emulsion size in vitro and promotes fecal fat excretion in healthy Japanese subjects. Lipids in Health and Disease 2015 Mar 20;14:20. Doi: 10.1186/s12944-015-0019-0

[x] Yadav H, Lee JH, Lloyd J, et al. Beneficial metabolic effects of probiotic via butyrate-induced GLP-1 hormone secretion. Journal of Biological Chemistry 2013 Aug 30;288(35):25088-97. Doi: 10.1074/jbc.M113.452516

[xi] Omar JM, Chan YM, Jones ML, et al. Lactobacillus fermentum and Lactobacillus amylovorus as probiotics alter body adiposity and gut microflora in healthy persons. Journal of Functional Foods 2013 Jan;5(1):116-23. Doi: 10.1016/j.jff.2012.09.001

[xii] Sanchez M, Darimont C, Drapeau V, et al. Effect of Lactobacillus rhamnosus CGMCC1.3724 supplementation on weight loss and maintenance in obese men and women. British Journal of Nutrition 2014 Apr 28;111(8):1507-19. Doi: 10.1017/S0007114513003875

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