장내 미생물이 발효를 통해 생성하는 단쇄지방산이 근육세포를 지구력형으로 바꿀 수 있다는 세포 연구 결과가 발표됐다.
국제학술지 《Frontiers in Physiology》2026년호에 실린 연구에서 연구팀은 C2C12 근관세포에 아세테이트 단독 또는 아세테이트·프로피오네이트·부티레이트 혼합물을 처리하고 근섬유 유형 변화를 분석했다.
결과에 따르면 0.5 mM 이상의 SCFA 혼합물을 처리했을 때 미토콘드리아 생합성을 촉진하는 PGC-1α와 Tfam 유전자 발현이 유의하게 증가했다. 또한 속근 섬유 표지자인 MyHC II는 감소하고,지근 섬유 표지자인 MyHC I은 증가해 근섬유가 산화형으로 이동하는 양상이 나타났다.
아세테이트 단독 처리에서도 유사한 방향의 변화가 관찰됐다. SCFA는 장내 식이섬유 발효 과정에서 생성되는 대사산물로, 장 건강뿐 아니라 전신 대사에도 광범위하게 영향을 미친다는 사실이 알려져 있다.
연구팀은 "장-근육 축을 통해 장내 미생물 대사산물이 근섬유 구성에 영향을 줄 수 있음을 보여주는 결과"라며 의미를 설명했다.
다만 이 연구는 세포 수준 실험에 그쳤으며, 동물 및 인체 연구에서도 동일한 효과가 재현되는지는 아직 확인되지 않았다. 지근 비율 증가가 실제 지구력 운동 능력 향상으로 이어지는지도 추가 연구가 필요하다.
식이섬유가 풍부한 식단을 통해 장내 SCFA 생성을 늘리는 것이 근육 구성에 긍정적 영향을 줄 수 있다는 가설을 뒷받침하는 연구이지만, 임상 적용을 위해서는 인체 실험 데이터가 요구된다.
※ 출처: Frontiers in Physiology, 2026. PMID: 41958524
Short-chain fatty acids (SCFAs), metabolites produced by gut bacteria during dietary fiber fermentation, can shift muscle cells toward an endurance-oriented, oxidative fiber profile, according to a new cell-based study published in Frontiers in Physiology in 2026.
Researchers used C2C12 myotubes — a well-established muscle cell model — to investigate the effects of acetate alone and a combination of acetate, propionate, and butyrate (SCFA mix) on muscle fiber characteristics and gene expression. These three SCFAs are the most abundant products of microbial fermentation in the colon.
When myotubes were treated with SCFA mixtures at concentrations of 0.5 mM or higher, the team observed significant increases in the expression of PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and Tfam (mitochondrial transcription factor A). Both genes are key drivers of mitochondrial biogenesis — the process by which cells produce more mitochondria, the organelles responsible for aerobic energy production.
In parallel, the cells showed a shift in myosin heavy chain (MyHC) isoform composition: MyHC I — the marker of slow-twitch, fatigue-resistant Type I fibers — increased, while MyHC II — associated with fast-twitch, glycolytic Type II fibers — decreased. Acetate alone produced directionally similar changes, suggesting it may be one of the primary active compounds driving these effects within the SCFA mixture.
The findings add to a growing body of evidence supporting the concept of a gut-muscle axis — a bidirectional communication pathway through which the gut microbiome and its metabolites influence skeletal muscle function and adaptation. Endurance training itself is known to promote a shift toward Type I fiber characteristics and increased mitochondrial density, and this study suggests that dietary factors influencing gut fermentation may amplify or partially replicate these adaptations at the cellular level.
However, several important caveats apply. This research was conducted exclusively in cell culture, and the extent to which these findings translate to living organisms — whether rodents or humans — remains unknown. The concentrations of SCFAs used in the study may not perfectly reflect what reaches muscle tissue in vivo following dietary fiber intake. Additionally, whether a shift in MyHC isoform expression in cell culture translates to measurable improvements in endurance performance in athletes requires separate investigation.
Nonetheless, the study provides a mechanistic rationale for exploring dietary fiber and gut microbiome modulation as potential indirect tools for muscle adaptation. Athletes and physically active individuals following fiber-rich diets may benefit from enhanced SCFA production, though claims about direct performance enhancement should await more robust human evidence.
Source: Frontiers in Physiology, 2026. PMID: 41958524
