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Cordyceps sinensis shows promise as an adjunct in Hashimoto’s thyroiditis, significantly reducing thyroid autoantibodies and inflammatory cytokines while improving free T4 levels. Fourteen randomized trials also indicate its immunomodulatory and anti-inflammatory effects.
What is Hashimoto’s thyroiditis?
Hashimoto’s thyroiditis (HT) is the most common autoimmune cause of hypothyroidism. Hypothyroidism is a condition where the thyroid gland doesn’t produce enough hormones, causing symptoms like fatigue, weight gain, and feeling cold. It is marked by elevated thyroid-peroxidase (TPOAb) and thyroglobulin autoantibodies (TgAb), progressive infiltration of immune cells—specifically lymphocytes—into the tissue, and eventual thyroid atrophy or fibrosis, when the thyroid gland gradually shrinks and loses its ability to work properly. Conventional care—low-iodine diet and levothyroxine (LT4)—manages hormone levels but does not address underlying autoimmunity or inflammation. Cordyceps sinensis (CS), also known as the Tibetan caterpillar fungus, is a parasitic fungus long used in traditional Chinese medicine. It contains nucleosides, polysaccharides, proteins, steroids, and other active ingredients, and exerts immunomodulatory and anti-inflammatory effects in preclinical models.
Review of what science knows
A study collected 14 randomized controlled trials with 1014 Hashimoto’s thyroiditis patients comparing Cordyceps sinensis preparations plus either a low-iodine diet or LT4 against those standard treatments alone. They summarized the results of the 14 trials based on the change of autoantibodies TPOAb and TgAb, and the production of the inactive free thyroxine (T4) and the free triiodothyronine (T3) thyroid hormones, and the thyroid-stimulating hormone (TSH) that is produced by the pituitary gland. They also assessed the changes in the relevant pro-inflammatory cytokines (TNF-α, IL-2, IL-6) and safety of the supplements.
To ensure the validity of the summary, data were pooled via random-effects meta-analysis, and evidence quality was rated good using GRADE (Grading of Recommendations Assessment, Development and Evaluation, a system for rating certainty in evidence).
Effect of Cordyceps sinensis
Decrease in the autoantibodies
Cordyceps sinensis with a low-iodine diet reduced the autoantibodies TPOAb by a large effect size and TgAb similarly, compared with diet alone. When Cordyceps sinensis was used together with LT4, both TPOAb and TgAb were further lowered versus LT4 alone.
Thyroid Hormones
In hypothyroid Hashimoto’s thyroiditis patients, Cordyceps sinensis plus LT4 significantly increased the pre-hormone T4, but had no clear effect on the active hormone T3. It also didn’t change the level of the thyroid gland, controlling the TSH hormone.
Reduced inflammation markers
Cordyceps sinensis plus LT4 markedly reduced pro-inflammatory cytokines (TNF-α, IL-2, IL-6) versus LT4 alone. Reducing their levels is beneficial because these molecules drive the thyroid-directed inflammation and tissue damage that underlie the disease. Lowering their concentrations can help calm the autoimmune attack on the thyroid, preserve healthier thyroid tissue, and improve symptoms like fatigue, swelling, and hormone imbalance.
Safety of Cordyceps sinensis
Adverse events, mainly nausea, gastrointestinal discomfort, and insomnia, occurred equally in control groups who did not take Cordyceps sinensis, and in the groups where patients ingested caterpillar fungus, suggesting that its consumption was safe.
How does caterpillar fungus work?
The polysaccharides and nucleosides in caterpillar fungus appear to modulate immune balance by reducing autoreactive antibody production, dampening the T helper immune cells Th1/Th17-driven inflammation, and upregulating anti-apoptotic pathways in thyroid cells to avoid their self-destruction. Animal models show that Cordyceps sinensis reduces lymphocytic infiltration and preserves thyroid gland architecture.
Limitations of the study
All clinical trials were single-center, small (47–120 participants each), and detailed randomization or blinding was not fully explained in every case. Study heterogeneity was high, thus, while results are promising, certainty remains to be supported by future studies with more participants.
Recommendation for Patients with Hashimoto’s Thyroiditis
At the present state of what we know of the effect of Cordyceps sinensis in Hashimoto’s thyroiditis, adjunctive use under strict medical monitoring by your doctor can be recommended.
Consider Cordyceps sinensis preparations in addition to standard levothyroxine therapy or a low-iodine diet, particularly if elevated autoantibodies (TPOAb/TgAb) or inflammatory markers persist despite optimal hormone replacement. Begin taking Cordyceps sinensis with lower doses, and check autoantibodies, T4 levels, and inflammatory cytokines every 3–6 months. Evidence covers 8–28 weeks of use, but in general, 12 weeks (3 months) of use is what may reveal significant benefits. If adjunctive use comes with side effects, consult your doctor and discontinue or adjust the dose.Conclusion
While larger multicenter clinical studies are needed, Cordyceps sinensis shows potential as a safe, immunomodulatory adjunct in Hashimoto’s disease, with measurable reductions in autoantibodies and inflammatory cytokines, and modest improvement in thyroid hormone levels.
If you want to read the details of the study, find here the original article: