DietaryMineral Density and Clinical Outcomes in Adults with Long COVID: A Cross-Sectional Analysis of Global and Sex-Specific Associations in the BioICOPER Study

Background/Objectives: The role of routine dietary mineral intake in the clinical expression of long COVID is poorly studied. The association between the energy-adjusted dietary density of nine minerals and 16 clinical outcomes was analyzed, exploring differences according to sex. Methods: Cross-sectional study in 290 participants of the BioICOPER study (93 men and 197 women). Intake was estimated with a validated seven-day record; calcium, iron, iodine, magnesium, zinc, selenium, sodium, potassium and phosphorus were expressed per 1000 kcal. Spearman correlations were performed with Benjamini–Hochberg correction (FDR), multivariable linear regression, bootstrap with 5000 resamplings and analysis by sex. Results: In the overall cohort (n = 290), bivariate correlations between dietary mineral densities and clinical outcomes were weak (|r| < 0.15), and none of the 144 tested associations survived false discovery rate (FDR) adjustment (q > 0.05). In exploratory multivariable regressions, higher iron and zinc densities were nominally associated with lower depressive symptoms. Formal mineral × sex interaction tests were restricted to k = 2 pairs that met screening criteria (iron and zinc with depressive symptoms); both were nominally significant (p bootstrap = 0.041 and 0.015, respectively) without correction for multiplicity, indicating tentative, exploratory findings. Conclusions: No robust global associations were observed between dietary mineral density and clinical burden. The identified associations, especially the relationship between zinc and depressive symptoms in women, are exploratory and require prospective confirmation.