Method for manufacturing a hyperpolarized amino acid, in particular glutamine, which substantially limits the formation of by-products, with respect to conventional aqueous preparations of sodium hydroxide with amino acids. The amino acid is in particular admixed with the hydroxide in the substantial absence of water and the dry mixture is dissolved in an anhydrous solvent in the presence of a polarizing agent. The obtained mixture is then subjected to a DNP process and can be used in metabolic MR imaging.