Vitamin C is a potent, powerful antioxidant that is best known for supporting immune health and wellness. Spring Valley Stomach Friendly Vitamin C Tablets use a patented immune health formula that stays in your system for 24 hours. Clinically studied to stay in the immune system longer than regular Vitamin C, it is carefully formulated to contain naturally occurring metabolites. Metabolites are substances derived from other compounds (such as nutrients) during the process of metabolism. The metabolites in this formula help enhance the retention of Vitamin C by your white blood cells, which are a vital component of your immune system.