I'm afraid that the best medical evidence disagrees with this; systematic meta-analyses of several large randomised controlled trials show that multivitamins have no effect in the prevention of major diseases (cardiovascular disease, cancer) or death; and that indiscriminate multivitamin supplementation may even cause some harms. http://annals.org/article.aspx?articleid=1789253

You can read more about the evidence around multivitamins, and the evidence of potential harms, here: https://www.sciencebasedmedicine.org/more-evidence-that-rout...