Dynamics of magnesium, copper, selenium and zinc serum concentrations for 2-year dietary intervention

Background & aims: Essential elements levels in serum are related to nutritional habits. We studied the association of magnesium (Mg), copper (Cu), zinc (Zn) and selenium (Se) concentrations in serum, with 3-dietary regimes, during 24-months of intervention. Methods: A representative subgroup (n = 231; age = 52 years; body-mass-index = 32.8kg/m²; 85% males) of the 2-year dietary-interventional-trial (DIRECT) who were randomized to low-fat, Mediterranean or low-carbohydrates diets, were followed for changes of the essential elements serum concentrations, using Inductively-coupled-plasma-mass-spectrometry (ICP-MS). Results: The essential elements serum concentrations significantly increased after 12-months of dietary intervention as follows: magnesium; 1.88 ±0.33 to 2.05 ±0.33mg/dL; p within group = 0.002, copper; 1109 ± 182 to 1245 ±371μg/L; p<0.001, selenium; 148 ± 37 to 173 ± 45μg/L; p<0.001 with no significant changes of zinc from baseline levels (955 ± 182μg/L to 991 ±284μg/L; p = 0.755). After 24-months, only magnesium continued to increase to 2.19 ±0.30mg/dL; p<0.001, while copper (1086 ±333μg/L; p = 0.534) and selenium (150 ±42μg/L; p = 0.581) returned to their baseline values. Zinc levels remained similar (930 ±221μg/L; p = 0.122). The changes (delta concentrations) were similar across the three diet types, after 12-months [p between groups = 0.274(Mg); 0.521(Cu); 0.521(Zn); 0.565(Se)] and 24-months [p = 0.462(Mg); 0.786(Cu); 0.295(Zn); 0.715(Se)]. Physical activity changes expressed as increasing Metabolic Equivalent Task (MET), after 12 months, decreased serum concentrations of zinc (β = -0.245 p = 0.006 and copper (β = -0.250, p = 0.006), as evaluated by multiple linear regression in the entire group adjusted to sex, age, diet group and weight-loss with the nutrients proteins, fibers, carbohydrates, fats intake changes as cofactors. Conclusions: Healthy dietary interventions significantly elevated the levels of magnesium over 2 years, while copper, and selenium serum concentrations increased within the first year only, similarly across the three diets. Increasing physical activity significantly decreased the serum concentrations of zinc and copper after 12-months.(ClinicalTrials.gov number, NCT00160108.).