PROBLEM TO BE SOLVED: To discover an effective and safe material that inhibits the formation of amyloid fibrils, and provide a food and a pharmaceutical composition containing the same.SOLUTION: The present invention provides a food and a pharmaceutical composition for inhibiting the formation of amyloid fibrils, containing fucoidan as an active ingredient, and also provides a food and a pharmaceutical composition for preventing amyloidosis, containing fucoidan as an active ingredient.SELECTED DRAWING: NoneCOPYRIGHT: (C)2018,JPO&INPIT【課題】アミロイド線維の形成を阻害する効果的かつ安全性の高い物質を見出し、それを含む食品や医薬組成物を提供する。【解決手段】フコイダンを有効成分として含むアミロイド線維形成阻害用食品およびアミロイド線維形成阻害用医薬組成物、ならびにフコイダンを有効成分として含むアミロイドーシス予防用食品およびアミロイドーシス予防用医薬組成物。【選択図】なし