be expected by continuous ingestion which is once or more a day the composition of the present invention when used as medicine may be in the form of drugs for oral administration for example the form may be a tablet a pill a hard capsule a soft capsule a microcapsule a powder a granule a liquid or the like when produced as medicine the composition of the present invention may be produced in a unit dose required for commonly approved drug administration by for example including a pharmaceutically approved material such as a carrier an excipient a filler an antiseptic a stabilizer a binder a ph modifier a buffer a thickener a gellant a preservative and an antioxidant accordingly as needed the composition of the present invention may also be used as a material for food and beverage or a material for animal feed for example the composition of the present invention or the peptide x pro pro y particularly the peptide val pro pro phe the peptide ile pro pro leu or the peptide asn ile pro pro leu which is the active ingredient of the composition of the present invention may be considered a functional food such as a food for specified health use which is effective in improving brain function the dose of administration or ingestion of the present composition the peptide x pro pro y particularly the peptide val pro pro phe the peptide ile pro pro leu or the peptide asn ile pro pro leu is preferably 0 1 mg kg weight to 10 mg kg weight per administration or ingestion in general in order to obtain desired effects in terms of the amount of x pro pro y particularly the peptide.