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Probiotics and Graves’ Disease: Potential Effects on Autoimmunity
Probiotics and Graves’ Disease: key takeways
- Gut health, probiotics, and Graves’ disease are exciting areas of research right now
- Stronger clinical data is still needed
- Gut-targeted therapies are being studied as potential supportive add-on therapies for Graves’ disease, not as standard treatment
- Probiotics may modestly influence immune markers such as TRAb
- We do not yet have proof that “fixing” the microbiome cures Graves’ disease
- Current evidence most strongly supports overall gut health strategies such as fibre-rich diets, Mediterranean-style eating patterns, avoiding smoking, stress management, sleep optimisation, and cautious exploration of probiotics
- Some of the strongest early findings currently come from Graves’ disease research involving Bifidobacterium longum alongside standard treatment
- Despite promising findings, probiotics have not consistently been shown to significantly improve thyroid hormone markers such as TSH, FT3, and FT4
Probiotics and Graves Disease’: key research findings
| Study | What Researchers Found |
| Masetti et al. 2021 | Changing gut bacteria in mice using antibiotics, probiotics, and stool transplants altered the severity of Graves’-like disease, suggesting the microbiome may influence autoimmune thyroid disease activity – at least in mice |
| Wu et al. 2021 | People taking the probiotic Bifidobacterium longum alongside antithyroid medication showed faster TRAb reductions and improved gut bacterial diversity compared with medication alone |
| Zhang et al. 2024 | A meta-analysis of 8 clinical trials found probiotics did not clearly improve thyroid hormone levels overall, but they may have modestly lowered TRAb antibodies in some people with Graves’ disease |
| INDIGO probiotic trial 2024 | Probiotics changed the gut microbiome (including increasing Bifidobacterium) and showed some promising effects on TRAb antibodies and immune markers, although major thyroid hormone improvements were not consistently observed. |
| Huang et al. 2024 probiotic Graves’ study | Certain Lactobacillus probiotic strains may help lower TRAb antibodies and improve symptoms alongside antithyroid medication, although evidence remains preliminary |
Two studies from the above stand out as particularly significant. A 2021 mouse study found that changing gut bacteria changed the severity of Graves’-like disease, suggesting the gut microbiome may influence autoimmune activity – at least in mice.
Then in 2024, a meta-analysis of eight randomized controlled trials provided some of the strongest human evidence so far. It found that probiotics may modestly reduce TRAb antibodies in some people with Graves’ disease.
What the evidence says about specific strains
Research is at an early stage and only a few specific strains have been studied so far. A few of them have shown promising results when used alongside standard Graves’ disease medication.
In a 2021 clinical study, people taking Bifidobacterium longum alongside the medication methimazole experienced faster reductions in TRAb antibodies compared with those taking just medication alone. Some thyroid markers and gut microbial diversity also improved.
Certain Lactobacillus strains have also shown potential. A 2024 study indicates that they may help reduce TRAb antibodies and improve symptoms alongside medication (the evidence remains preliminary).
The 2024 INDIGO probiotic trial found that probiotic supplementation increased beneficial bacteria such as Bifidobacterium and showed some promising effects on immune markers and TRAb antibodies. In the same year, a meta-analysis of eight randomized controlled trials also found that probiotics may modestly reduce TRAb antibodies in some people with Graves’ disease. However, in both studies, improvements in thyroid hormone levels were either less clear or less consistent.
Overall, the research so far suggests probiotics may have a greater effect on immune activity – particularly TRAb antibodies – than on thyroid hormone levels themselves.
However, compared with nutrients such as selenium – which currently has stronger clinical evidence in Graves’ disease – we have a long way to go – probiotic research is still early.
Limitations: to take note of
Many studies have been relatively small, short-term, or lower quality, and have used different probiotic strains, doses, and treatment combinations, making results difficult to compare directly.
Probiotics were often studied alongside standard thyroid medications such as methimazole or levothyroxine, making it difficult to determine how much benefit came from the probiotic itself.
Researchers also still do not fully understand whether changes in the gut microbiome contribute to thyroid disease, or whether thyroid disease and its treatments alter the gut microbiome.
While some findings are promising, we need more expansive, well-designed human clinical trials to show results before probiotics can be considered an established supportive therapy for Graves’ disease.
Lactobacillus: the research is mixed
Although Lactobacillus probiotics are often considered beneficial, the research in Graves’ disease is more complicated than it first appears. One animal study found that a probiotic mixture containing Lactobacillus and Bifidobacterium appeared to worsen Graves’-like eye disease. Other studies have also found higher levels of Lactobacillus bacteria in some people with Graves’ disease compared with healthy individuals.
This does not mean Lactobacillus is harmful in Graves’ disease. However, it suggests that probiotic effects may depend on the exact strain being used and the individual’s underlying condition. This is another reason why more research is still needed before any specific probiotic can be confidently recommended for Graves’ disease.
References
Shu Q, Kang C, Li J, Hou Z, Xiong M, Wang X, Peng H et al. (2024). Effect of probiotics or prebiotics on thyroid function: A meta-analysis of eight randomized controlled trials. PLOS ONE 19(1):e0296733. https://doi.org/10.1371/journal.pone.0296733
FAQ’s
Can probiotics improve thyroid function?
Current research has not consistently shown that probiotics significantly improve thyroid hormone levels such as TSH, FT3, or FT4. However, some studies suggest they may help support gut health and immune activity linked to thyroid disease.
What is the gut-thyroid axis?
The gut-thyroid axis is the idea that gut health and thyroid health may be connected. Researchers believe gut bacteria may influence immune function, inflammation, nutrient absorption, and potentially thyroid health.
What probiotics have been studied in Graves’ disease?
The main probiotic groups studied so far in Graves’ disease include Bifidobacterium and Lactobacillus species. Some studies have also examined multistrain probiotic formulas. However, only a small number of strains have been specifically researched in Graves’ disease, and scientists still do not know which strains may be most effective.
Which probiotic currently looks most promising for Graves’ disease?
Based on current research, Bifidobacterium longum is one of the most promising probiotic strains being studied, particularly in Graves’ disease. In one study, it was associated with reductions in TRAb levels when used alongside standard Graves’ medication.
However, much larger studies are still needed before any probiotic can be considered a proven thyroid therapy.
Can probiotics help Graves’ disease?
Some early research suggests certain probiotics and microbiome-targeted therapies may help influence immune markers involved in Graves’ disease, particularly TRAb levels. However, probiotics are not currently considered a treatment for Graves’ disease and should not replace medical care.
Can probiotics replace thyroid medication?
No. Current evidence does not support probiotics as a replacement for thyroid medication such as levothyroxine, methimazole, or carbimazole.
Are probiotics safe for people with thyroid disease?
Most studies suggest probiotics are generally well tolerated in people with thyroid conditions. However, probiotic effects may depend on the strain used, the specific thyroid condition, and the individual person.
Is Lactobacillus good for Graves’ disease?
The evidence is currently mixed. Some studies suggest Lactobacillus species may support gut and immune health, while other research has raised questions about possible negative effects in Graves’ disease and Graves’ orbitopathy models.
Researchers still do not fully understand which strains may be beneficial, neutral, or potentially problematic in autoimmune thyroid disease.
Why are scientists interested in probiotics and thyroid disease?
Researchers are interested because people with autoimmune thyroid conditions often show differences in their gut microbiome compared to healthy individuals. Scientists are now trying to understand whether certain gut bacteria may contribute to immune dysfunction linked to thyroid disease.
Is berberine being studied for Graves’ disease?
Although berberine is not a probiotic, some researchers have explored its effects alongside standard Graves’ disease medication. In one study, patients receiving berberine alongside methimazole experienced more effective normalization of TSH and FT3 levels compared with methimazole alone. However, the research is still early-stage, and larger human studies are needed before berberine can be recommended for Graves’ disease.
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