(approved for use as a food additive in the UK, U.S. Canada, Australia and New Zealand) E301 sodium ascorbate (approved for use as a food additive in the UK, U.S., Canada, Australia and New Zealand) E302 calcium ascorbate (approved for use as a food additive in the UK, U.S. Canada, Australia and New Zealand) E303 potassium ascorbate (approved in Australia and New Zealand, but not in the UK, U.S. or Canada) E304 fatty acid esters of ascorbic acid such as ascorbyl palmitate (approved for use as a food additive in the UK, U.S., Canada, Australia and New Zealand) The stereoisomers of Vitamin C have a similar effect in food despite their lack of efficacy in humans. They include erythorbic acid and its sodium salt (E315, E316). Pharmacology Pharmacodynamics Vitamin C – specifically, in the form of ascorbate – performs numerous physiological functions in the human body by serving as an enzyme substrate or cofactor and an electron donor. These functions include the synthesis of collagen, carnitine, and neurotransmitters; the synthesis and catabolism of tyrosine; and the metabolism of microsomes. During biosynthesis, ascorbate acts as a reducing agent, donating electrons and preventing oxidation to keep iron and copper atoms in their reduced states. Vitamin C functions as a cofactor for the following enzymes: Three groups of enzymes (prolyl-3-hydroxylases, prolyl-4-hydroxylases, and lysyl hydroxylases) that are required for the hydroxylation of proline and lysine in the synthesis of collagen. These reactions add hydroxyl groups to the amino acids proline or lysine in the collagen molecule via prolyl hydroxylase and lysyl hydroxylase, both requiring vitamin C as a cofactor. The role of vitamin C as a cofactor is to oxidize prolyl hydroxylase and lysyl hydroxylase from Fe to Fe and to reduce it from Fe to Fe. Hydroxylation allows the collagen molecule to assume its triple helix structure, and thus vitamin C is essential to the development and maintenance of scar tissue, blood vessels, and cartilage. Two enzymes (ε-N-trimethyl-L-lysine hydroxylase and γ-butyrobetaine hydroxylase) are necessary for synthesis of carnitine. Carnitine is essential for the transport of fatty acids into mitochondria for ATP generation. Hypoxia-inducible factor-proline dioxygenase enzymes (isoforms: EGLN1, EGLN2, and EGLN3) Dopamine beta-hydroxylase participates in the biosynthesis of norepinephrine from dopamine. Peptidylglycine alpha-amidating monooxygenase amidates peptide hormones by removing the glyoxylate residue from their c-terminal glycine residues. This increases peptide hormone stability and activity. Absorption, metabolism and excretion From the U.S. National Institutes