A method for producing a polyglycerol ester of 3-hydroxybutyric acid, which polyglycerol ester is optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, wherein an optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, 3-oxobutyric acid polyglycerol ester which comprises at least one 3-oxobutyrate radical (3-oxobutyric acid radical) of the general formula (I') CH 3 - C - CH 2 - C O - (I') is subjected, by means of at least one reducing agent, to a selective reduction of the at least one 3-oxobutyrate radical of the general formula (I') positioned at the keto group - C - of the acetyl function CH 3 - C - so as to result a 3-hydroxybutyrate radical (3-hydroxybutyric acid radical) of the general formula (II') CH 3 - CH - CH 2 - C O - (II') wherein the optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, 3-oxobutyric acid polyglycerol ester, used as a starting compound, corresponds to the general formula (Ib) R 1 O - CH 2 - CH(OR 1) - CH 2 - [O - CH 2 - CH(OR 1) - CH 2] p - OR 1 (Ib) wherein, in the general formula (Ib), • the variable p represents an integer from 1 to 4, preferentially 1 or 2, more preferably 1, • the radical R 1, each independently of one another, identical or different, represents: hydrogen, CH 3 - C - CH 2 - C - or a radical R 2, wherein the radical R 2 represents a radical of the type linear or branched, saturated or mono- or polyunsaturated (C 4 -C 33 -alkyl) - C -, preferably (C 7 -C 33 -alkyl) - C -, however, with the proviso that at least one radical R 1, especially at least two radicals R 1, does not represent hydrogen, and with the proviso that at least one radical R 1, especially at least two radicals R 1, represents a radical CH 3 - C - CH 2 - C -; and wherein the reducing agent is selected from the group of hydrogen, hydrides and alcohols as well as mixtures thereof; and wherein the reduction is carried out as a complete reduction or else as a non-complete reduction of all keto groups - C - of the acetyl function CH 3 - C - of the at least one 3-oxobutyrate radical of the general formula (I') to a 3-hydroxybutyrate radical of the general formula (II'); so that, as a reaction product, an optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, 3-hydroxybutyric acid polyglycerol ester is obtained. wherein an optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, 3-oxobutyric acid polyglycerol ester which comprises at least one 3-oxobutyrate radical (3-oxobutyric acid radical) of the general formula (I') CH 3 - C - CH 2 - C O - (I') is subjected, by means of at least one reducing agent, to a selective reduction of the at least one 3-oxobutyrate radical of the general formula (I') positioned at the keto group - C - of the acetyl function CH 3 - C - so as to result a 3-hydroxybutyrate radical (3-hydroxybutyric acid radical) of the general formula (II') CH 3 - CH - CH 2 - C O - (II') wherein the optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, 3-oxobutyric acid polyglycerol ester, used as a starting compound, corresponds to the general formula (Ib) R 1 O - CH 2 - CH(OR 1) - CH 2 - [O - CH 2 - CH(OR 1) - CH 2] p - OR 1 (Ib) wherein, in the general formula (Ib), • the variable p represents an integer from 1 to 4, preferentially 1 or 2, more preferably 1, • the radical R 1, each independently of one another, identical or different, represents: hydrogen, CH 3 - C - CH 2 - C - or a radical R 2, wherein the radical R 2 represents a radical of the type linear or branched, saturated or mono- or polyunsaturated (C 4 -C 33 -alkyl) - C -, preferably (C 7 -C 33 -alkyl) - C -, however, with the proviso that at least one radical R 1, especially at least two radicals R 1, does not represent hydrogen, and with the proviso that at least one radical R 1, especially at least two radicals R 1, represents a radical CH 3 - C - CH 2 - C -; and • the variable p represents an integer from 1 to 4, preferentially 1 or 2, more preferably 1, • the radical R 1, each independently of one another, identical or different, represents: hydrogen, CH 3 - C - CH 2 - C - or a radical R 2, wherein the radical R 2 represents a radical of the type linear or branched, saturated or mono- or polyunsaturated (C 4 -C 33 -alkyl) - C -, preferably (C 7 -C 33 -alkyl) - C -, however, with the proviso that at least one radical R 1, especially at least two radicals R 1, does not represent hydrogen, and with the proviso that at least one radical R 1, especially at least two radicals R 1, represents a radical CH 3 - C - CH 2 - C -; and wherein the reducing agent is selected from the group of hydrogen, hydrides and alcohols as well as mixtures thereof; and wherein the reduction is carried out as a complete reduction or else as a non-complete reduction of all keto groups - C - of the acetyl function CH 3 - C - of the at least one 3-oxobutyrate radical of the general formula (I') to a 3-hydroxybutyrate radical of the general formula (II'); so that, as a reaction product, an optionally C 5 -C 34 -fatty acid functionalized, especially optionally C 8 -C 34 -fatty acid functionalized, 3-hydroxybutyric acid polyglycerol ester is obtained.