肥満のカギを握る腸内古細菌と糞便中グリココール酸濃度~腸内古細菌の枯渇と糞便中グリココール酸濃度の上昇が肥満と相関することを解明~

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2025-03-10 北海道大学

北海道大学遺伝子病制御研究所の山村凌大助教らの研究グループは、北海道寿都町の住民を対象に、肥満度と糞便成分および腸内細菌叢の関連性を調査しました。その結果、肥満群では糞便中のグリココール酸(GCA)濃度が有意に高く、GCA濃度が高い群では、古細菌Methanobrevibacter属が検出されないことが明らかになりました。この古細菌はGCAの脱抱合に関与する酵素を持ち、肥満者における腸内古細菌の減少と糞便中GCA濃度の上昇が示されました。これらの結果は、腸内環境が肥満に及ぼす影響を示唆しています。

<関連情報>

糞便中グリココール酸濃度の増加は、古細菌の枯渇と関連して肥満と相関する:ドサンコ健康調査 Increased fecal glycocholic acid levels correlate with obesity in conjunction with the depletion of archaea: The Dosanco Health Study

Ryodai Yamamura, Ryo Okubo, Shigekazu Ukawa, Koshi Nakamura, Emiko Okada, Takafumi Nakagawa, Akihiro Imae, Takashi Kimura, Akiko Tamakoshi
The Journal of Nutritional Biochemistry  Available online: 23 January 2025
DOI:https://doi.org/10.1016/j.jnutbio.2025.109846

Graphical abstract

肥満のカギを握る腸内古細菌と糞便中グリココール酸濃度~腸内古細菌の枯渇と糞便中グリココール酸濃度の上昇が肥満と相関することを解明~

Highlights

  • A comprehensive study of 30 fecal components and their association with obesity.
  • Fecal glycocholic acid (GCA) and obesity showed a significant positive correlation.
  • Patients with high fecal GCA were depleted of an archaeal genus, methanobrevibacter.
  • Archaeal depletion may affect bile acid metabolism, potentially contributing to obesity.

Abstract

Recent studies have focused on the relationship between obesity and gut microbiota. This study aims to identify fecal components and gut bacterial species associated with different BMI categories. In this study, 538 participants aged ≥18 years were categorized into underweight, normal, and obese groups based on BMI (cutoffs: 18.5 and 25.0 kg/m²). We compared 30 fecal components among these groups and calculated correlation coefficients between each component and BMI. Participants were then divided into quartiles based on fecal component levels correlated with BMI, and the prevalence ratio (PR) of obesity was calculated, adjusted for confounding factors. We also analyzed the composition and diversity of gut microbiota and bacterial gene expression among the quartiles for each fecal component. Fecal glycocholic acid (GCA) showed a significant positive correlation with BMI. The PR for obesity in the highest quartile of fecal GCA was 3.30 (95% CI, 1.21–9.54), indicating a significantly higher risk of obesity compared to the lowest quartile. Gut microbiota analysis revealed significant differences in the abundance of Ruminococcaceae Incertae Sedis, Faecalibacterium, and Methanobrevibacter, with Methanobrevibacter being absent in the higher quartiles of fecal GCA. Additionally, gene expression for enzymes involved in the deconjugation of conjugated bile acids, including GCA, was downregulated in the highest quartile. Increased fecal GCA levels are positively correlated with obesity, alongside a depletion of archaea.

医療・健康
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