The buffered form of vitamin C is created when you have the ascorbic acid reacting with mineral carbonates (a salt of carbonic acid). As ascorbic acid prefers to bind with metals, this isn’t a very complicated process, and the end product is a white powder with a salty taste. The minerals combined with the ascorbic acid are usually sodium, calcium, potassium, and magnesium, leading to sodium ascorbate (E301), calcium ascorbate (E302), potassium ascorbate (E303), and magnesium ascorbate. Out of these four, the most common ones to ingest as a vitamin C supplement are calcium ascorbate and magnesium ascorbate, while the other two are more often found as food additives.