PureDefense chewables provide a comprehensive blend of nutrients and herbal extracts designed to support immune function in a convenient, great-tasting, chewable tablet. EpiCor Saccharomyces cerevisiae fermentate contains numerous immune enhancing bioactive metabolites designed to support both the innate and adaptive immune response. Research suggests that it enhances natural killer cell activation, B cell and T cell function, and secretory IgA levels. In two randomized, double-blind, placebo-controlled trials, EpiCor provided statistically significant support for upper respiratory tract health and overall immune health. Elderberry extract provides anthocyanins, flavonoids and other polyphenols that have been shown to support immune function. Studies have shown statistically significant immune support throughout the lifespan. Quercetin maintains healthy mast cell function by supporting healthy enzyme activity. Zinc and vitamin C, provided as the non-acidic enhanced retention Ester-C, help to promote immune defense by supporting immune cell proliferation, activation and function, as well as healthy antioxidant enzyme function.