You will be provided with a reference and some statements. Please determine whether each statement is 'supported', 'unsupported', or 'unknown' with respect to the reference. Please note:
First, assess whether the reference contains any valid content. If the reference contains no valid information, such as a 'page not found' message, then all statements should be considered 'unknown'.
If the reference is valid, for a given statement: if the facts or data it contains can be found entirely or partially within the reference, it is considered 'supported' (data accepts rounding); if all facts and data in the statement cannot be found in the reference, it is considered 'unsupported'.

You should return the result in a JSON list format, where each item in the list contains the statement's index and the judgment result, for example:
[
    {
        "idx": 1,
        "result": "supported"
    },
    {
        "idx": 2,
        "result": "unsupported"
    }
]

Below are the reference and statements:
<reference>
ScienceDirect



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Reference number:
a3be9830b9b1dd00
IP Address:
208.110.231.2
User Agent:
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/153.0.0.0 Safari/537.36
Timestamp:
2026-09-16 08:45:21 UTC
CPE00001
::CLOUDFLARE_ERROR_1000S_BOX::
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</reference>

<statements>
1. Epidemiologic and mechanistic studies suggest that dysregulated plasma or serum levels of several metals are associated with increased risks of coronary heart disease (CHD), stroke, arrhythmias, and cardiovascular mortality, raising the question of whether intentional modulation (e.g., supplementation or chelation) could be preventive or therapeutic.
2. In the Dongfeng-Tongji cohort of over 6,000 Chinese adults, higher plasma copper, molybdenum, and vanadium were positively associated with all-cause and CVD mortality, whereas higher manganese, selenium, and thallium were inversely associated with these risks. In multivariable models, participants in the highest quartile of plasma copper had almost a twofold higher risk of CVD death compared with the lowest quartile, while those in the highest quartile of selenium had substantially lower CVD mortality.
3. These studies collectively indicate that both deficiency and excess of specific metals can contribute to cardiovascular risk, and that multi-element profiles rather than single metals may be more informative.
4. Observational data indicate that higher dietary and plasma selenium are associated with lower CVD prevalence and mortality, though high selenium levels have also been linked to dyslipidemia and diabetes risk in some populations, underscoring a narrow optimal range.
5. Meta-analyses of randomized trials suggest that selenium supplementation may have modest favorable effects on lipid profiles in some contexts, but consistent reductions in hard cardiovascular outcomes have not been demonstrated.
6. Because selenium has a narrow therapeutic window and potential metabolic side effects at high doses, routine selenium supplementation for cardiovascular prevention is not currently supported by strong evidence; individualized approaches based on baseline status may be more appropriate.
7. In general population cohorts, higher plasma copper and certain other metals (molybdenum, vanadium) are associated with increased risks of all-cause and CVD mortality, while higher manganese and selenium are associated with reduced risks.
8. Zinc and selenium supplementation can cause toxicity at high doses or with prolonged use; high selenium status has been associated with dyslipidemia and diabetes risk, and excessive zinc can interfere with copper metabolism.
9. Zinc and selenium are promising in specific contexts, particularly where deficiency is present, and may reduce oxidative stress or improve certain risk factors, but evidence for event reduction is limited and potential risks at high exposures require caution.
10. Iron, copper, and other metals show complex, often ambivalent associations with cardiovascular outcomes, and no clear preventive or therapeutic supplementation strategies have emerged; inappropriate modulation may be harmful.
</statements>

Begin the assessment now. Output only the JSON list, without any conversational text or explanations.