In childhood and adolescence an adequate mineral intake is essential for normal growth and immune function, and to prevent chronic diseases in adulthood. The aim of this study was to analyse the dietary intake of Ca, Mg, Fe, Zn and Cu in children and adolescents from an orphanage-school in Guatemala and to assess the mineral contribution of nutritional supplements used by this population. Mineral content was analysed in nutritional supplements, bioaccesible fractions obtained after an in vitro gastrointestinal method, and diets sampled by a 7-day duplicate diet study. The average mineral content in the duplicate diets, including supplements, was (mg/d): Ca 452, Mg 230, Fe 25, Zn 8 and Cu 0.22. Especially Ca and Cu values were below recommended daily intakes. The content of these minerals in the nutritional supplements (mg/serving) was 49-112 for Ca, 1.2-3.8 for Fe, 24-47 for Mg, 0.7-4.16 for Zn and 0.08-0.23 for Cu. A great proportion of dietary minerals was provided by supplements, the contribution of which was: Ca 53.1%, Mg 58.4%, Fe 27.6%. Zn 82.2% and Cu 98.5%. Mineral bioaccessibility in supplements was particularly low for Ca and, to a lesser extent, for Fe and Zn. In spite of the high supplement consumption (up to 4 servings/d) important mineral deficiencies were detected in the diet of institutionalised children. Findings suggest that formulation and nutritional values of supplements used in Latin America should be carefully reviewed, in order to be a useful tool in the prevention and treatment of hidden hunger.