BACKGROUND: Magnesium is a vital mineral that plays a crucial role in various physiological processes, and its imbalance has been associated with many chronic aging-related diseases. Traditional assessment methods are insufficient, and the Magnesium Depletion Score (MDS) has been proposed as a significant indicator. Klotho, a transmembrane protein, is involved in aging regulation and oxidative stress modulation. Despite the shared relevance of MDS and Klotho to aging, their relationship remains unclear. AIMS: This study aims to investigate the relationship between MDS and Klotho levels in U.S. adults. METHODS: We performed a cross-sectional analysis utilizing information from the NHANES database (2007-2016), including 8285 participants. MDS was computed according to specific criteria, encompassing alcohol intake, proton pump inhibitor utilization, diuretic utilization, and renal function. Participants were categorized into groups according to MDS score: none to low (score = 0 or 1), medium (score = 2), and high (score >
2). The association between MDS and Klotho levels was assessed using weighted multivariable linear regression models and subgroup analysis. RESULTS: The analysis revealed a negative association between MDS and serum Klotho levels after comprehensive adjustment. Participants with the highest MDS showed decreased Klotho concentrations compared to those with the lowest level. This association remained robust even after excluding outliers. Subgroup analysis indicated a stronger correlation between MDS and serum Klotho concentration in individuals aged 40-60 years, women, and those with normal weight. CONCLUSION: The findings suggest a negative association between MDS and Klotho levels, indicating that magnesium metabolism may influence Klotho expression. These results underscore the potential significance of magnesium in aging processes and age-related diseases, highlighting the potential benefit of increasing serum Klotho concentration through magnesium supplementation.