Where is the strongest evidence that selenium supplementation helps a thyroid disorder?
Answer: The strongest evidence is from studies of patients with Graves’ orbitopathy.
What is Graves’ orbitopathy (GO)?
Answer: GO, also known as thyroid eye disease, is an inflammatory autoimmune disorder. It affects the tissues around the eyes. It causes swelling and discomfort. Most frequently, it affects individuals who have Graves’ disease [Cleveland Clinic 2026].
What does the clinical evidence show about selenium supplementation and Graves’ orbitopathy?
Answer: In 2026, Kostadinov et al examined data from five RCTs including 303 patients with Graves’ Orbitopathy. 165 patients received selenium; 138 received placebo or no selenium. Selenium supplementation resulted in a significant reduction in clinical activity score. However, the meta-analysis showed no significant differences in Quality of Life improvement or in visual function [Kostadinov 2026].
In 2024, Sharabati et al analyzed data from four RCTs. Compared to placebo, selenium supplements were superior at six months in lowering the clinical activity score, in improving total quality of life, and in improving the visual and the psychological functioning scores of patients. Moreover, selenium supplements significantly improved these outcomes at 12 months.
Which RCT is the most convincing selenium supplementation study?
Answer: The 2011 Marcocci multicenter RCT enrolled 159 patients with mild Graves’ orbitopathy. Patients received selenium supplements (sodium selenite 100 mcg twice daily), pentoxifylline, or placebo for six months, with six months of follow-up. Compared with placebo, the selenium supplementation significantly improved Graves’ orbitopathy–specific quality of life.
In addition, the study findings showed [Marcocci 2011]:
- Selenium improved overall ophthalmic outcomes.
- Selenium slowed down disease progression.
- Selenium benefits persisted at the 12-month assessment, six months after stopping treatment.
- Selenium was well tolerated.
- Pentoxifylline was not clearly beneficial and caused more gastrointestinal adverse effects.
Note: Pentoxifylline is a medication design to improve the flow of blood through blood vessels [Mayo Clinic 2026].
Which retrospective study showed benefits of selenium supplementation?
Answer: in 2026, Lumyongsatien et al reported on a retrospective review of the medical records of patients with Graves’ Orbitopathy. The GO patients had received selenium supplementation with a total daily dose of 210 mcg for six months. The selenium supplementation correlated positively with significant increases in selenium concentrations and significant improvements in clinical activity score, eyelid edema, and quality of life [Lumyongsatien 2026].
Conclusion: How can selenium supplements benefit Graves’ Orbitopathy patients?
Answer: The following points may explain the relationship between selenium and Graves’ Orbitopathy [Schomburg 2012; Lumyongsatien 2026].
- The thyroid has a high requirement for selenium.
- Low selenium intakes and low selenium status may contribute to thyroid autoimmunity.
- Autoimmune attacks may cause inflammation around the eyes.
- The inflammation creates biochemical stress and tissue damage.
- Selenium can help the body’s antioxidant defenses clean up some of the biochemical stress. In turn, that may reduce inflammation and limit further tissue damage.
- Furthermore, selenium supplementation may help moderate immune activity. Sufficient selenium intakes may make the autoimmune attacks somewhat less intense.
Sources
Cleveland Clinic staff. Thyroid Eye Disease (Graves’ Eye Disease). 2025. Retrieved from https://my.clevelandclinic.org/health/diseases/17558-thyroid-eye-disease
Kostadinov N et al. Efficacy of selenium supplementation in graves’ orbitopathy: a systematic review and meta-analysis of randomized controlled trials with trial sequential analysis. J. Clin. Med. 2026;15(12):4710.
Lumyongsatien M et al. Selenium supplementation in Graves’ Orbitopathy: effects on blood concentrations and clinical outcomes. Clinical Ophthalmology. 2026;20:569805.
Marcocci C, Kahaly GJ, Krassas GE, et al. Selenium and the course of mild Graves’ orbitopathy. N Engl J Med. 2011;364(20):1920-1931.
Mayo Clinic. Pentoxifylline (oral route). 2026. Retrieved from https://www.mayoclinic.org/drugs-supplements/pentoxifylline-oral-route/description/drg-20065425
Schomburg L. Selenium, selenoproteins and the thyroid gland: interactions in health and disease. Nat Rev Endocrinol. 2012;8(3):160-171.
Sharabati I et al. The efficacy and safety of selenium supplementation versus placebo in the treatment of Graves’ orbitopathy: a systematic review and meta-analysis of randomised controlled trials. Clin Endocrinol (Oxf). 2024;101:669-681.
The information presented in this review article is not medical advice. The reader should not use this information as medical advice.