The present invention addresses the problem of providing a brain function improving agent and a prophylactic or therapeutic agent for cognitive dysfunction, each of which does not induce diarrhea and/or nausea, has a form that is easy to ingest, enables the production of a ketone compound in a human body, is novel and safe, and has little adverse side effects. The present invention provides a brain function improving agent and a prophylactic or therapeutic agent for cognitive dysfunction, each of which comprises a protein, a medium-chain fatty acid triglyceride that serves as a lipid, and a carbohydrate, wherein the protein, the medium-chain fatty acid triglyceride that serves as a lipid and the carbohydrate are contained in amounts of 5 to 50 parts by weight, 5 to 80 parts by weight and 1 to 50 parts by weight, respectively, relative to 100 parts by weight of each of the agents.本發明係以提供無下痢及/或嘔吐，且以容易攝取的形態，可發揮於人體內之酮體生成的新穎之安全無副作用的腦功能改善劑及認知功能障礙的預防或治療劑為課題。本發明係提供調配蛋白質、作為脂質之中鏈脂肪酸三甘油酯、碳水化合物，每100重量份含有蛋白質5至50重量份、作為脂質的中鏈脂肪酸三甘油酯5至80重量份、及碳水化合物1至50重量份之腦功能改善劑、認知功能障礙的預防及治療劑。
