PROBLEM TO BE SOLVED: To increase the amount of total fatty acids in vivo by increasing the production of fatty acids in vivo, and to increase the amount of fatty acids in vivo. In-vivo polyunsaturated fatty acid content increasing agent, in-vivo fatty acid composition that enhances in-vivo polyunsaturated fatty acid production, increases in-vivo highly unsaturated fatty acid content, and modifies in-vivo fatty acid composition Provided are a modifier and a polyunsaturated fatty acid synthesis gene expression promoter that promotes the expression of the polyunsaturated fatty acid synthesis gene in vivo and increases the expression level of the gene. SOLUTION: In-vivo fatty acid content-increasing agent, in-vivo highly unsaturated fatty acid-increasing agent, in-vivo fatty acid composition-modifying agent, or highly-unsaturated fatty acid synthesis gene expression containing a pear (Pyrus communis L.) extract as an active ingredient Accelerator. [Selection diagram] None【課題】生体内における脂肪酸の生成を促進して生体内の総脂肪酸量を増加させる生体内脂肪酸含量増加剤、生体内における高度不飽和脂肪酸の生成を促進して生体内の高度不飽和脂肪酸量を増加させる生体内高度不飽和脂肪酸含量増加剤、生体内における高度不飽和脂肪酸の生成を促進して生体内の高度不飽和脂肪酸量を増加させ、生体内の脂肪酸組成を改変する生体内脂肪酸組成改変剤、及び生体内における高度不飽和脂肪酸合成遺伝子の発現を促進して当該遺伝子の発現量を増加させる高度不飽和脂肪酸合成遺伝子発現促進剤を提供する。【解決手段】セイヨウナシ（Pyruscommunis L．）抽出物を有効成分とする、生体内脂肪酸含量増加剤、生体内高度不飽和脂肪酸含量増加剤、生体内脂肪酸組成改変剤、又は高度不飽和脂肪酸合成遺伝子発現促進剤。【選択図】なし
