The Study
Low level of selenium predicts high incidence of colorectal cancer
This study looked at lots of other studies and found that people who eat more selenium-rich foods tend to get less colorectal cancer. But it doesn’t prove that selenium stops cancer—it just shows they often go together, like how people who wear helmets might also ride bikes slower.
Analysis score
Maximum 85 for a systematic review with meta-analysis.
Where the score came from
This study looked at many older studies to see if people who eat more selenium (a mineral in food) are less likely to get colon cancer.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 547 / 100
Quality score
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The drop in risk is real in observational studies, but taking selenium pills hasn't been shown to help in clinical trials—so eating selenium-rich foods might help, but supplements probably won't.
- 2People who ate more selenium through food had a 26% lower risk of colorectal cancer.
- 3This link was strongest in Europe and Oceania, and only for colon cancer—not rectal cancer.
- 4Blood and toenail selenium levels didn't show a clear link.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
BMC Public Health
Year
2026
Authors
Jiacheng Ying, Hongsheng Fang, Cheng Zhang, Tianlong Ling, Jiaying Tang
Related Content
Claims (5)
In humans, having too little or too much selenium in the body is linked to worse health outcomes.
People who consume more selenium through their diet have a lower risk of developing colorectal cancer, but measuring selenium in blood or toenails does not show a consistent link to this cancer risk.
People who consume more selenium through their diet have a 26% lower risk of developing colorectal cancer compared to those who consume less.
People with higher selenium exposure have a 19% lower risk of developing colon cancer, but their risk of rectal cancer is not affected.
In regions like Europe and Oceania, higher selenium levels are consistently linked to lower rates of colorectal cancer, while this link is weaker in North America and Asia.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.