Involvement of brown adipose tissue in diurnal variations of postprandial thermogenesis and metabolism

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K11013
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 59040:Nutrition science and health science-related
• Research Institution: Hokkaido University
• Principal Investigator: Saito Masayuki 北海道大学, 獣医学研究院, 名誉教授 (80036441)
• Co-Investigator(Kenkyū-buntansha): 松下 真美 天使大学, 看護栄養学部, 講師 (60517316)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 褐色脂肪組織 / 日内変動 / 食事時刻 / エネルギー消費 / 肥満

Outline of Final Research Achievements

Disturbed circadian rhythm is associated with an increased risk of obesity and metabolic disorders. Brown adipose tissue (BAT) is a site of nonshivering thermogenesis (NST) and plays a role in regulating energy expenditure (EE) and body fatness. In this study, we examined diurnal variations of cold- and diet-induced NST in healthy humans by focusing on their relation to BAT activity. Changes in EE and BAT-related skin temperature after cold exposure in the morning were higher in a High-BAT group than in a Low-BAT group, whereas those in the evening was comparable in the two groups. Change in EE after breakfast was higher in the High-BAT group than in the Low-BAT group, whereas those after dinner was comparable in the two groups. Thus, BAT-associated NST shows diurnal variations, being higher in the morning than in the evening, and may be involved in the association of an eating habit of breakfast skipping with obesity and related metabolic disorders.

Free Research Field

栄養生理学

Academic Significance and Societal Importance of the Research Achievements

肥満・メタボは過食と身体活動・運動不足に起因するが、朝食欠食など、生活リズムの乱れも一因となることが知られているが、そのメカニズムは不明であった。本研究で、食事摂取後の熱産生（エネルギー消費）に関わる褐色脂肪が日内変動しており、夜に較べて朝の方が活性が高いことをヒトで初めて明らかにした。したがって、夕食よりも朝食を欠落した方が、エネルギー消費に対する影響もより大きく、長期間続くと体脂肪が蓄積されやすくなるのであろう。この成果は、褐色脂肪が活性化する朝や午前中に食事や運動を行うなど、日内リズムを踏まえた肥満・メタボの予防・改善策の指針として、社会的意義は大きいと思われる。