PRO Vital C-LD® is a proprietary preparation of ascorbic acid with citrus bioflavonoids and lipid metabolites from natural vegetable sources. LD is crucial to the bioavailability of vitamin C, and it ensures that this vital antioxidant reaches cells throughout the body. LD significantly increases vitamin C's bioavailability versus vitamin C without LD. It is essential for vitamin C to travel intact through the stomach and into the intestines, by which the specific lipid metabolites contained in PRO Vital C-LD® enhance its entry into the cells. PRO Vital C-LD® does not cause stomach upset the way traditional supplements often do.