The purpose of the present invention is to improve the bioavailability of glucosamines. The present invention relates to a method for improving the bioavailability of glucosamines including having a subject orally ingest glucosamines after three or more hours of fasting and within six hours after the time when the amount of period gene mRNA expression peaks within a day.本發明之目的為使葡萄糖胺類之生物學利用率提升。本發明係關於提升葡萄糖胺類之生物學利用率的方法，其包含在絕食3小時以上後，且Period基因的mRNA表現量成為於1日中最大之時間以後6小時以內，使對象經口攝取葡萄糖胺類。
