MULTIVITAMIN USE AND ITS INFLUENCE ON THE IMMUNE RESPONSE IN HEALTHY ADULTS: AN ANALYSIS BETWEEN THERAPEUTIC EFFECT AND PLACEBO RESPONSE

Abstract

The use of multivitamin supplements is widespread among healthy adults and supported by the belief that daily intake enhances immune function and prevents infections. However, current scientific evidence indicates that, in the absence of nutritional deficiencies, the therapeutic effects are limited and often confounded by subjective responses associated with the placebo effect. This integrative literature review, conducted through PubMed, Scopus, Web of Science, and SciELO databases from 2015 to 2025, analyzed clinical trials, systematic reviews, and meta-analyses addressing the relationship between multivitamin supplementation and immune response in healthy adults. Findings show that vitamins C, D, A, E, zinc, and selenium are essential for immune integrity, yet supplementation in well-nourished individuals yields no significant physiological improvement. Reported benefits are largely attributed to psychobiological mechanisms of the placebo effect, mediated by positive expectations and activation of neuroendocrine pathways of well-being. It is concluded that multivitamin use should be clinically indicated only in cases of confirmed deficiency, avoiding unnecessary medicalization of healthy behaviors. Future studies should employ rigorous designs to differentiate biological effects from placebo responses and support evidence-based prescription practices.

DOI: https://doi.org/10.56238/sevened2025.037-001