Buffered Vitamin C (with Bioflavonoids)A powerful antioxidant, vitamin C is a water soluble vitamin necessary to form collagen in bones, cartilage, muscle and blood vessels. It also aids in the absorption of iron. Metabolic Maintenance uses only USP quality (99. 5% or higher purity) vitamin C, with a pH equal to 2. 4. For patients who want to supplement their diet with additional vitamin C, their buffered formulas combine low acidity potassium magnesium ascorbate with lemon bioflavonoids