The present invention relates to a liquid formulation for human and animal nutrition, consisting of an aqueous solution, a guanidinoacetic acid component and at least one methyl group donor from the group of choline, methionine and betaine. In addition to the free guanidinoacetic acid, it is also possible to use salts, adducts and/or complexes as the guanidinoacetic acid component, which can additionally be combined with further physiologically active compounds. Since the guanidinoacetic acid component is present in dissolved form, formulations including those in the form of mineral water, lemonade, alcoholic drinks and drinking water formulations are envisaged. It has been found that, surprisingly, the guanidinoacetic acid component present in this liquid formulation has very good stability and is converted very rapidly to creatine in the body.
