Home›Nutrition & Obesity Medicine› Selenium Shows Inconclusive Mucositis Benefit in Cancer Therapy, Exploratory Toxicity Reduction
Selenium Shows Inconclusive Mucositis Benefit in Cancer Therapy, Exploratory Toxicity ReductionSelenium May Reduce Certain Side Effects During Cancer Treatment
Frontiers in MedicinePublished October 7, 2026DOI ↗Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease
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Key Takeaway
Interpret selenium's exploratory toxicity reduction cautiously given very low certainty.
This meta-analysis assessed selenium supplementation in patients undergoing cancer therapy, with a primary focus on severe oral mucositis during head-and-neck radiotherapy or chemoradiotherapy. The analysis included 188 patients in the primary analysis and 30 study groups overall, comparing selenium with placebo, no selenium, observation, or selenium-free standard care.
For the primary outcome of severe oral mucositis, the result was inconclusive: RR 0.89 (95% CI 0.50 to 1.56, fixed-effects) and RR 0.89 (95% CI 0.35 to 2.23, Hartung-Knapp). For broad exploratory outcomes covering gastrointestinal and hematologic events, a statistically significant reduction was reported: RR 0.60 (95% CI 0.42 to 0.83, fixed-effects) and RR 0.60 (95% CI 0.40 to 0.89, Hartung-Knapp).
The authors note several limitations: high risk of bias in 8 studies, some concerns of bias in 9 studies, substantial heterogeneity, very low certainty of evidence, and a small number of studies for some estimates. Safety data, including adverse events, serious adverse events, discontinuations, and tolerability, were not reported. Funding and conflicts of interest were also not reported.
The authors conclude that selenium may attenuate selected treatment-related toxicities (gastrointestinal and hematologic), but the evidence is not sufficient to support routine universal supplementation. The certainty of evidence was very low for the primary outcome and very low for exploratory outcomes despite a consistent direction of effect. Prevention of severe oral mucositis and routine universal supplementation should not be overstated.
How this fits prior evidence
This meta-analysis addresses a gap not covered in prior evidence summaries, which have focused on nursing-led inflammation-sensitive care, natural polysaccharides with immunotherapy, hope in pediatric oncology, antidiabetic medications and survival, and surgery for liver metastases. Unlike those topics, this review specifically evaluates selenium supplementation for treatment-related toxicities in cancer therapy. The inconclusive primary outcome for severe oral mucositis and very low certainty of evidence contrast with the more definitive associations reported for metformin and SGLT2 inhibitors in prior coverage, underscoring the need for cautious interpretation.
Researchers looked at how selenium supplements affect patients undergoing treatment for cancer, specifically those receiving radiation or chemotherapy for head and neck issues. The analysis included data from 30 different study groups to see if selenium could reduce common side effects like mouth sores or digestive problems.
The results showed that selenium might help reduce gastrointestinal and hematologic events, which are issues involving the digestive tract and blood. However, the evidence for whether selenium prevents severe oral mucositis, which are painful mouth sores, was not clear. Because the study had a very low certainty of evidence and some studies had a high risk of bias, the results are not definitive.
While the data suggests some potential benefits for certain side effects, the evidence is not strong enough to recommend selenium as a standard treatment for everyone. Patients should talk to their doctors before starting any new supplements to determine if it is appropriate for their specific treatment plan.
What this means for you:
Selenium may reduce some side effects, but evidence is too weak to recommend it as a standard treatment.
Common questions
Can selenium help with side effects during cancer treatment?
The study found that selenium supplementation may lead to a statistically significant reduction in gastrointestinal and hematologic events. These are common side effects for patients undergoing cancer therapy. However, the evidence is considered to have very low certainty, meaning more research is needed to be sure of the results.
Does selenium prevent mouth sores during radiation?
The results regarding severe oral mucositis, which are painful mouth sores, were inconclusive. While some studies were included, the evidence was not strong enough to confirm if selenium prevents these specific sores during head and neck radiotherapy or chemoradiotherapy.
Should everyone take selenium during cancer treatment?
The evidence is not sufficient to support routine universal supplementation for all patients. Because the study had a low certainty of evidence and some high risks of bias, patients should consult their medical team before starting any new supplements.
BackgroundTrials of selenium for cancer supportive care vary in treatment context, formulation, dose, toxicity domain, and outcome definition. We evaluated the efficacy and safety of selenium supplementation for preventing or reducing cancer therapy-related toxicities.MethodsPubMed, Web of Science Core Collection, and the Cochrane Library were searched through June 30, 2026. Comparative clinical trials conducted during cancer therapy compared selenium with placebo, no selenium, observation, or selenium-free standard care. Two reviewers independently completed study selection, data extraction, outcome evaluation, and risk-of-bias assessment, with third-reviewer adjudication when required. Severe oral mucositis during head-and-neck radiotherapy or chemoradiotherapy was the primary outcome; broader pools were exploratory. Fixed- or random-effects analyses were supplemented by restricted maximum-likelihood models with Hartung-Knapp confidence intervals. Conference-abstract and derived-odds-ratio analyses were restricted to supplementary sensitivity analyses. Certainty was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD420261448497).ResultsOf 444 records, 333 unique records were screened. Forty-one of 49 sought reports were assessed in full text, and 31 reports representing 30 study groups were included; 17 groups contributed to the main analysis and 13 to supplementary evidence. Overall risk of bias was judged to be Some concerns for nine studies and High risk for eight. The four-study primary analysis (188 participants) was inconclusive (risk ratio [RR] 0.89, 95% confidence interval [CI] 0.50 to 1.56; I2 44.9%; very low certainty), as was the Hartung-Knapp analysis (RR 0.88, 95% CI 0.35 to 2.23). Five conventional exploratory confidence intervals crossed the null under Hartung-Knapp analyses. Across domains, the pooled estimate remained below the null (baseline RR 0.60, 95% CI 0.42 to 0.83; Hartung–Knapp RR 0.60, 95% CI 0.40 to 0.89; 11 studies), but heterogeneity was substantial and the certainty of evidence was very low.ConclusionCurrent evidence does not establish prevention of severe oral mucositis, but the consistent cross-domain direction and several domain-specific exploratory estimates suggest that selenium may attenuate selected treatment-related toxicities, particularly gastrointestinal and hematologic events, in appropriately selected settings. Because the majority of estimates are based on few, heterogeneous, and high-risk studies, these signals should inform targeted trials rather than routine universal supplementation.Systematic review registrationThis systematic review was registered with PROSPERO. Unique Identifier: CRD420261448497.
