Bidirectional associations of zinc supplement intake with biological ageing interacted by metabolic equivalent of task: A large-scale population-based Biobank study.

BACKGROUND: The association of zinc intake with biological ageing and whether physical exercise modifies this association remain uncertain. We aimed to explore the correlations between zinc intake and biological ageing and to evaluate the modifying effect of physical exercise. METHODS: Data were extracted from 68,947 participants in the Biobank. Daily zinc intake and biological age were calculated using standard equations, and physical exercise was measured by the metabolic equivalent of task (MET) per week. Generalized linear regression models, adjusted for confounding factors, were employed to explore the associations between zinc intake and biological ageing. Pre-specified subgroup and sensitivity analyses were performed to identify effect modification of MET and to validate the robustness of findings, respectively. RESULTS: The regression models revealed that zinc intake with recommended dose was associated with 0.13-year delayed biological age [95 % Confidence Interval (CI) = -0.21 to -0.05], while an excessive intake of zinc (>40 mg per day) was associated with 3.23-year biological age acceleration (95 % CI = 0.18 to 6.28). Participants adhering to the recommended zinc intake combined with sufficient physical exercise (>600 MET per week) demonstrated a 31 % lower likelihood of experiencing accelerated biological ageing compared to those with inadequate zinc intake and insufficient physical exercise (Odds Ratio = 0.69, 95 % CI = 0.66 to 0.74, p < 0.001). Subgroup analyses indicated that the association between zinc intake and delayed biological ageing was more pronounced in the low-income population with an annual household income before tax of less than £30,999 (P-interaction <0.001). Sensitivity analyses confirmed the robustness of these results. CONCLUSION: A recommended dose of zinc intake is associated with delayed biological ageing, with physical exercise exceeding 600 MET per week enhancing this association. Conversely, excessive zinc intake is linked to accelerated biological ageing. We suggest that people take daily zinc supplements with caution.