Z-stack is an Immune System Formula Developed by Dr. Vladimir (Zev) Zelenko OBM to Prevent Treat Viruses and Maximize Your Immune Function Expires 11/2026 Zinc Immune Support Zinc is one of the active ingredients in Z-Stack. It is one of the most well-known immune support ingredients to date. Quercetin Plant-based Nutrients Quercetin is a leading active ingredient in Z-Stack. Being a plant flavonol, quercetin is a natural source of vital nutrients. Vitamin C Vitamin C is an essential nutrient involved in the repair of tissue and the enzymatic production of certain neurotransmitters Vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects Immune Function