How does selenium status relate to mortality?
Higher biomarker levels of selenium status correlate significantly with lower mortality rates. This is the conclusion of a 2025 meta-analysis of 20 cohort studies. Importantly, the central finding in the meta-analysis was a consistent inverse association between selenium status and mortality [Cui, Schomburg et al 2025].
Basically, one standard deviation increase in selenium status corresponded to the following reduction in mortality:
- 13% lower all-cause mortality
- 11% lower cardiovascular mortality
- 15% lower cancer mortality
Moreover, Cui et al found low serum Selenoprotein P (SELENOP) concentrations associated with an increased risk of stroke in subjects free of cardiovascular disease and with increased risk of cardiovascular mortality among heart disease patients. The association of SELENOP concentrations with cardiovascular disease incidence was restricted to patients with hypertension or diabetes [Cui 2025].
Note: These studies by Cui et al are observational evidence. They are not evidence from studies of selenium supplementation.
What were the cohort studies analyzed in the Cui study?
Of the 20 studies analyzed, 17 addressed all-cause mortality, nine addressed cardiovascular mortality, and seven addressed cancer mortality. Altogether, the 20 studies comprised more than 60,000 study participants.
Consistently, the association of selenium status with all-cause mortality remained similar across different research protocols:
- countries with different selenium availability
- laboratory measurement methods
- recruitment periods
- follow-up durations
- study sizes
In addition, the researchers judged that most included studies had relatively low risk of bias [Cui 2025].
What did the 2016 KiSel-10 observational study show about low selenium status and mortality risk?
The 2016 Alehagen observational study followed 668 elderly Swedes for about 6.8 years. Their mean serum selenium was very low: 67.1 mcg/L. After Alehagen et al had adjusted for such potentially confounding variables as COPD, diabetes, impaired heart function, sex, and smoking, the study participants in the lowest selenium quartile had a 56% higher risk of cardiovascular mortality and a 43% higher risk of all-cause mortality than the remainder of the cohort [Alehagen 2016 Jan].
Thus, the Alehagen all-cause result and cardiovascular result are consistent with Cui’s broader findings.
How did daily selenium supplementation help the elderly Swedish citizens who had low selenium?
Later in 2016, Alehagen et al reported findings from a secondary analysis of data from the KiSel-10 randomized clinical trial. Of the 668 elderly Swedish citizens low in selenium, 219 individuals received combined daily supplementation for four years:
- Selenium as selenium-enriched yeast 200 mcg
- Coenzyme Q10 in the ubiquinone form 200 mg
Then, the remaining participants (n = 449) received either placebo (n = 222) or no treatment (n = 227). For all three study groups, the researchers registered all cardiovascular mortality based on death certificates and autopsy reports [Alehagen 2016 Jul].
Among people who did not receive supplementation, cardiovascular mortality was 24.1% in those with selenium status below 65 mcg/L versus 13.0% in those with selenium status above 85 mcg/L. Thus, in the unsupplemented individuals, the lower selenium status corresponded to substantially greater cardiovascular mortality.
Significantly, among the individuals with the lowest baseline selenium status, cardiovascular mortality was only 12.1% in the study participants receiving daily selenium and CoQ10 supplements. In contrast, the unsupplemented individuals with the lowest baseline selenium status had an average cardiovascular mortality of 24.1% — an absolute difference of about 12 percentage points.
Moreover, the apparent beneficial effect with respect to lower cardiovascular mortality persisted 12 years after the commencement of the four-year intervention [Alehagen 2018].
Meanwhile, the apparent benefit became smaller in people with higher baseline selenium. The benefit of selenium supplementation was not statistically significant in individuals above 85 mcg/L.
Conclusion: Selenium Status and Mortality
The meta-analysis by Cui et al. shows that low selenium status is a biomarker of increased mortality risk.
Prof. Alehagen’s observational study is an example of the relationship between selenium status and mortality in a selenium-poor elderly Swedish population.
Data from Prof. Alehagen’s KiSel-10 randomized controlled trial suggest that selenium supplementation of people with low selenium status can result in lower mortality rates.
The KiSel-10 findings suggest that selenium supplementation has its greatest benefit in people with low selenium status. The KiSel-10 study data do not show that raising selenium status above an adequate level will provides additional protection.
Sources
Alehagen U et al. Relatively high mortality risk in elderly Swedish subjects with low selenium status. Eur J Clin Nutr. 2016 Jan;70(1):91-6.
Alehagen U et al. Supplementation with selenium and Coenzyme Q10 reduces cardiovascular mortality in elderly with low selenium status. a secondary analysis of a randomised clinical trial. PLoS One. 2016 Jul 1;11(7):e0157541.
Alehagen U et al. Still reduced cardiovascular mortality 12 years after supplementation with selenium and coenzyme Q10 for four years. PLoS One. 2018 Apr 11;13(4):e0193120.
Cui Z, Xie R, Lu X, Schomburg L, Brenner H, Schöttker B. Associations of selenium status with all-cause and cause-specific mortality: a systematic review and meta-analysis of cohort studies. Redox Biol. 2025 Sep;85:103755.
Cui Z, Schomburg L et al. Serum selenoprotein P concentrations and cardiovascular disease: results from a large, prospective cohort study of older German adults. Free Radical Biology and Medicine. 2025;239:270-279.
The information presented in this review article is not medical advice. The reader should not use this information as medical advice.