Many older adults do not get enough zinc, vitamin C and vitamin D, and this can be related to decreased ability to fight infection. The purpose of this research study is to determine if taking a multivitamin/mineral supplement every day for 12 weeks will increase the ability of immune cells in blood to kill bacteria.

Vitamins C and D and the mineral zinc are each considered immune modulating micronutrients, but their specific effects on the immune system, especially when used in combination, is relatively unknown. Deficiency in each of these micronutrients is frequently observed in aging adults and may contribute to age-related declines in immune status. Based on prior published studies, the investigators hypothesize that supplementation of older adults with a combination of vitamin C, vitamin D, and zinc will increase the innate ability of neutrophils to kill invading bacteria through a variety of mechanisms, including increased phagocytosis, antimicrobial peptide expression and changes in reactive oxygen species (ROS) production. Therefore, this study is designed to investigate the effects of Redoxon VI, a supplement consisting of a combination of vitamin C, vitamin D, and zinc on functional markers of the immune system of healthy, older adults when compared to a matched placebo. To accomplish this, the investigators will recruit 40 healthy adults between the ages of 60 and 75 and randomize them to either Redoxon VI or an identical, inactive placebo control supplement to be taken twice a day for 12 weeks. Since neutrophil-mediated killing is a crucial defense against Staphylococcus aureus infection that declines with age, it will serve as a primary outcome in this study. Using blood collected from individuals before and after supplementation, the investigators will measure the ability of neutrophils to clear S. aureus cells, and compare the killing activity in those individuals receiving the vitamin and mineral supplement to those receiving the placebo. The investigators will confirm these changes in immune cell function by also measuring phagocytic activity in neutrophils, as well as their ability to produce ROS. As secondary measures of immune function, the investigators will also determine circulating levels of neutrophils, monocytes and lymphocytes, measure cathelicidin antimicrobial peptide (also known as hCAP18/LL-37) levels, and determine changes in circulating levels of inflammatory cytokines. Based on previous studies, the investigators expect that any increase in functional immune status will correspond to changes in vitamins C, D and zinc status in these individuals. The investigators expect the results from this study to provide the foundation for future studies investigating combinations of supplements on immune function and more extensive studies using these micronutrients to restore declines in immune function observed in older adults.