Viruses, bacteria, and fungi invade the host cells and activate their machinery to escape from the host defense system. Hostage environment for the foreign particle activates the combat between immune system and microorganism. Adjunct therapy is usually administered along with regular therapy for better clinical outcomes. Since it is known that antioxidants improve immune response against various bacterial and viral infections, antioxidant supplements are often given for their treatment. In HIV-infected people, low concentrations of macro- and micronutrients are associated with increased disease progression and high mortality. Supplementing antiretroviral therapy (HAART) along with multivitamins has been shown to delay the disease progression. The adjunct therapy of vitamins A, C, and E improves T cell-mediated immune response and T-cell proliferation.