Can Probiotics Help The Thyroid?


Welcome to my blog entitled ‘Can Probiotics Help The Thyroid?”.

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Can Probiotics Help The Thyroid?

Probiotics are non-pathogenic microorganisms that can reach the colon alive, having beneficial health effects for their host. In hypothyroidism and hyperthyroidism, Lactobacillaceae and Bifidobacteriaceae are often reduced. Lactobacillus reuteri supplementation proved to benefit the thyroid function in mice by increasing free T4, thyroid mass, and physiological parameters, like more active behavior. This effect could be triggered by interleukine-10 and subsequent enhanced T-regulatory cells. In broiler chickens, two studies examined increased T3 and T4 levels after the supplementation of probiotics. Synbiotic supplementation is a combination of pro- and pre-biotics and a recent study showed beneficial effects on patients with hypothyroidism by significantly reducing TSH, levothyroxine dose, and fatigue and increasing fT3. No influence on anti-TPO or blood pressure was observed. However, when conferring animal studies, it must be considered that microbiota in different animal species are not obligatory comparable to humans. Zhou et al. found no stimulating or impairing effect of probiotics Lactobacillaceae and Bifidobacteriaceae with regards to autoimmune thyroid diseases.

Interestingly, microbes like E. coli function as a reservoir for T3 by binding it to bacterial thyroid-binding hormone and are able to prevent thyroid hormone fluctuating and thus, possibly reduce the need for T4 supplementation.

Spaggiari et al. investigated the influence of Lactobacilli and Bifidobacteriaceae probiotics on levothyroxine. They found a significantly lower adjustment requirement of T4 in the study compared to the control group, reasoning that microbiota modification increases levothyroxine availability and stabilizes thyroid function. They concluded that probiotics have a beneficial role in lowering serum hormone fluctuations, also considering that iodothyronines deconjugation is regulated by bacterial enzymes sulfatases and ß-glucuronidases, which could be more available due to probiotics.

Probiotics seem to be able to accumulate trace elements such as selenium, zinc, and copper and incorporate them into organic compounds. Considering that selenium, zinc, and probiotics operate via different pathways and all of them are favorable for the thyroid, there could be a synergistic effect for health when incorporating all of them, especially in deficient conditions.

Probiotics could constitute an adjuvant therapy for thyroid diseases; nonetheless, it must be considered that most studies on probiotics rely on animal models.

Probiotics And Graves Disease

In one 6-month study the researchers were evaluating the curative effects of probiotics supplied with methimazole on thyroid function of patients with Graves. Patients divided into three treatment groups:

  1. Methimazole.
  2. Methimazole + black bean.
  3. Methimazole + probiotic Bifidobacterium longum.

Unsurprisingly, methimazole intake significantly improved several thyroid indexes but not the most important thyrotropin receptor antibody (TRAb), which is an indicator of the Graves recurrence rate (2).

The authors also found that the clinical thyroid indexes of patients with Graves in the probiotic supplied with methimazole treatment group continued to improve.

Dramatically, the concentration of TRAb recovered to the healthy level (2).

Mechanistic exploration implied that the consumed probiotic regulated the intestinal microbiota and metabolites (2).

These metabolites impacted neurotransmitter and blood trace elements through the gut-brain axis and gut-thyroid axis, which led to improved thyroid function (2).



Conclusions: Probiotics For Thyroid Health

Probiotics have shown beneficial effects in thyroid diseases and are able to have a positive effect on trace elements such as selenium, zinc, and copper.

Additionally, certain gut bacteria function as a reservoir for T, the all important thyroid hormone, and are able to prevent thyroid hormone fluctuating and thus may be able to reduce the need for T4 supplementation.

Probiotics could constitute an adjuvant therapy for thyroid diseases.


  1. Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function? (click here)
  2. Probiotic Bifidobacterium longum supplied with methimazole improved the thyroid function of Graves’ disease patients through the gut-thyroid axis (click here)
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