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>
Client Challenge



A required part of this site couldn’t load. This may be due to a browser
extension, network issues, or browser settings. Please check your
connection, disable any ad blockers, or try using a different browser.
</reference>

<statements>
1. A Mendelian randomization study using genetic instruments for serum magnesium levels (CARDIoGRAMplusC4D data, over 60,000 CAD cases) found that a genetically predicted 0.1 mmol/L increase in serum magnesium was associated with a 12% lower odds of coronary artery disease. This strengthens the case that the observed inverse association between serum magnesium and CHD risk is at least partly causal and supports further testing of magnesium-targeted interventions.
2. Overall, oral magnesium supplementation is feasible, generally safe, and capable of improving certain surrogate markers (arterial stiffness, lipids, blood pressure), especially in individuals with low baseline magnesium, but direct evidence that it reduces clinical cardiovascular events is still lacking.
3. Meta-analyses cited in this study indicate that magnesium supplementation can reduce postoperative arrhythmias (e.g., after cardiac surgery), but evidence for primary prevention of atrial fibrillation in the general population remains preliminary.
4. Observational associations are subject to confounding and reverse causation; although Mendelian randomization supports a role for serum magnesium, similar genetic evidence is limited for other metals.
5. Magnesium stands out as the metal ion with the most consistent observational, genetic, and mechanistic support for a protective role in cardiovascular disease, and supplementation appears to improve some cardiovascular risk factors and surrogate markers in certain populations. However, large randomized trials with hard endpoints (MI, stroke, CVD mortality) are still needed before magnesium supplementation can be widely recommended as a primary preventive therapy.
</statements>

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