Methyl malonate is a chemical compound with the formula C5H8O4. It is an ester formed from the reaction of malonic acid and methanol. Methyl malonate is used in organic synthesis and can serve as a building block for various chemical reactions, including the production of pharmaceuticals and agrochemicals. In the human body, methyl malonate is involved in the metabolism of certain amino acids and fatty acids. Elevated levels of methyl malonate can indicate a deficiency in vitamin B12, which is essential for proper metabolic function. Monitoring methyl malonate levels can help diagnose metabolic disorders.