OBJECTIVES: The market for food supplements is booming thanks to their increased consumption. European regulations include different ways in which vitamins and minerals are administered, without making it clear to the consumer whether one formulation has advantages over the other. The aim of this review was to compare the bioavailability of different forms of magnesium and analyze the differences between them. METHODS: Based on a PICO (population, intervention, comparison, outcome) research question, a search strategy was established for magnesium bioavailability studies comparing different forms in the PubMed, Cochrane, Web of Science, and Scopus databases. We found 433 studies, out of which 14 were finally selected. RESULTS: Inorganic formulations appear to be less bioavailable than organic ones, and the percentage of absorption is dose dependent. CONCLUSIONS: All magnesium dietary supplements can maintain physiological levels in healthy people without prior deficit, although this cannot be assured in older people or those with illnesses or previous subphysiological levels.