The invention relates to a method for preparing a dietetic or pharmaceutical composition, comprising the following steps: a) a preparation containing rutin, in particular ground tatary buckwheat, is mixed with a protein solution in a weight ratio protein solution/buckwheat from 1 to 100 (or vice versa), wherein before the addition of buckwheat, the protein solution has been heated above room temperature, b) the mixture from step a) is held for a period of at least 10 to 1,000 s at a temperature >；50° C., and c) subsequently to step b), the mixture is cooled down to a temperature below 45° C. The invention further relates to thus obtainable preparations and to the uses thereof.
