Higher Selenium Intake Tracks With Lower Screening-Defined MCI Prevalence
Dietary selenium intake was inversely associated with screening-defined mild cognitive impairment in a multicenter sample of older adults in Zhejiang, China, while hypertension moved in the opposite direction. The pattern is clinically interesting because it places a trace dietary nutrient and a common vascular risk factor on the same cognitive map in a community-dwelling population aged 55 years and older.
The study enrolled 1084 adults across four regions in Zhejiang Province in 2020, with 1033 participants retained for the primary regression analyses after incomplete data were excluded. Cognitive status was assessed with standardized scales, diet was captured through a food frequency questionnaire, and physical examination data were incorporated into the final models. Screening-defined MCI was present in 251 participants, equal to 24.3% of the analytic cohort.
Higher selenium intake lined up with progressively lower MCI prevalence across intake quartiles. Compared with the lowest quartile, adjusted prevalence ratios were 0.51 in the second quartile, 0.37 in the third, and 0.30 in the highest quartile. The gradient is hard to ignore: each step up in selenium intake corresponded to a lower prevalence of cognitive impairment by screening criteria.
Hypertension moved the other way. Its adjusted prevalence ratio for screening-defined MCI was 1.40, placing vascular burden squarely in the same frame as cognitive vulnerability.
Why Selenium and Blood Pressure May Converge on the Brain
Selenium is biologically plausible in this setting because it is tied to antioxidant defense, redox balance, and inflammatory regulation. In older adults, those pathways matter for the brain’s microvasculature and for neuronal resilience, especially when chronic vascular stress is already present. Hypertension can injure small vessels, impair cerebral perfusion, and accelerate white matter damage; selenium insufficiency may compound that stress by weakening the body’s ability to buffer oxidative injury.
The joint analysis pushed this idea further. Among participants with hypertension and dietary selenium intake below 100 µg/day, prevalence of screening-defined MCI was highest when compared with those without hypertension and with the same lower intake range. In adjusted terms, the prevalence ratio for the hypertensive, lower-selenium group reached 1.82. The combination suggests a biologically coherent clustering of risk, not just two independent variables sitting side by side in a regression table.
One sentence captures the bedside meaning. Blood pressure burden and low selenium intake appeared to travel together toward worse cognitive screening outcomes.
The study design does not prove causality, and it cannot separate whether low selenium intake contributes directly to cognitive decline or whether it is a marker for a broader dietary pattern that is itself protective. Cross-sectional work cannot determine temporal order, and cognitive impairment can also affect diet quality through changes in appetite, food choice, or independence. Even so, the associations were strong enough to keep both nutrition and vascular control in view when older adults are assessed for early cognitive symptoms.
The Size of the Association Is Larger Than a Minor Dietary Signal
The prevalence ratios are notable because they were not modest nudges around the null. A ratio of 0.30 in the highest selenium quartile versus the lowest indicates a substantial inverse association within this community sample, even after adjustment for measured covariates. The joint hypertension analysis also suggests effect concentration: low selenium intake may be especially unfavorable when vascular risk is already elevated.
The article’s approach relied on modified Poisson regression with a log link and robust variance, a sensible choice for estimating prevalence ratios in a cross-sectional cohort where the outcome is common. This matters because odds ratios can exaggerate effects when prevalence is high, and MCI prevalence in this sample was substantial at 24.3%.
Dietary assessment was based on a converted food composition table derived from the FFQ, which is standard for population nutrition research but still vulnerable to recall error and misclassification. Selenium intake was estimated rather than directly measured in blood or tissue, so the exposure reflects habitual diet rather than biomarker-confirmed selenium status. That leaves room for measurement noise, yet the overall trend remained consistent across quartiles and in the joint analysis.
What the Findings Mean for Community Screening
In practical terms, the data argue for a more integrated view of cognitive screening in older adults. Blood pressure control remains essential, but dietary patterns may also deserve attention, especially in regions where selenium intake could be variable. The study does not justify supplementation by itself, and it does not establish an optimal target intake for preventing cognitive decline. It does, however, show that lower dietary selenium intake and hypertension coexist with a higher prevalence of cognitive impairment on screening.
The sample came from community-dwelling adults in Zhejiang Province, so the findings are best understood in that demographic and nutritional context. Regional food availability, dietary patterns, and background selenium exposure can differ substantially across China and even more across countries. Generalizing the results beyond this population should be done cautiously.
A second blunt point follows from the design. Screening-defined MCI is not the same thing as a confirmed neurocognitive diagnosis, and the study used a screening framework rather than a longitudinal dementia endpoint. This makes the result valuable for risk identification, but not for treatment decisions that would require randomized or prospective evidence.
A Nutritional Signal That Deserves Prospective Testing
The strongest clinical message is that cognition in older adults may not be explained by vascular risk alone. Selenium intake appeared to track with lower prevalence of impairment, while hypertension raised the prevalence, and the two exposures together produced the highest burden in the low-selenium, hypertensive subgroup. That pattern fits a model in which oxidative stress, endothelial dysfunction, and cerebrovascular injury jointly erode cognitive reserve.
The funding structure and ethics oversight were straightforward, and the study was conducted with ethical approval and informed consent in place. Those procedural details do not change the biology, but they support the credibility of the cohort data.
What the field still needs is prospective follow-up with repeated dietary assessment, biomarker-based selenium measurement, and incident cognitive outcomes. A longitudinal design would show whether selenium status precedes cognitive decline, whether blood pressure modifies that trajectory, and whether the combination of the two can identify a high-risk subgroup early enough for intervention. Until then, the current findings remain an association study with an intriguing nutritional-vascular signal and a clear need for confirmation.