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Background <p>Although whole grains (WG) are widely recommended for health, the divergent impacts of WG versus refined grains (RG) on metabolism, body composition, and inflammation, mediated by distinct short-chain fatty acid (SCFA) profiles, require deeper investigation in older adults. This secondary analysis of a randomized controlled trial aimed to elucidate these differential effects and explore the specific mediating roles of SCFA changes.</p> Methods <p>While maintaining their habitual non-staple food intake, 102 participants were randomly assigned to either the WG or RG groups and provided with standardized ingredients for staple food preparation. Fecal SCFAs, blood pressure, blood glucose, renal function markers, body composition, and systemic immune-inflammation markers were assessed at baseline and post-intervention, with further exploration of inter-variable correlations and mediation pathways among these factors.</p> Results <p>WG favored butyrate percentage, while RG increased acetate proportion. WG consumption improved post-prandial diastolic blood pressure (DBP), an effect not observed in the RG group, and yielded a significantly greater reduction in serum creatinine. Conversely, RG intake resulted in statistically significant short-term body composition changes, reducing fat mass and increasing lean mass. Mediation analysis revealed that changes in butyrate and acetate acted as suppressors in the pathways linking dietary grain type to post-prandial DBP and blood urea nitrogen changes, respectively. Systemic immune-inflammation markers did not differ between groups.</p> Conclusion <p>In our study, we observed that WG and RG consumption elicited distinct SCFA profiles and divergent metabolic and body composition responses in middle-aged and older adults. WG intake preferentially benefited blood pressure and renal function, potentially through SCFA-related pathways, while RG intake unexpectedly improved short-term body composition. These findings highlight the complexity of grain-microbiota-host interactions and suggest that the grain consumed substantially influences metabolic outcomes through SCFA-mediated mechanisms.</p> <p>Clinical trial registration number: ChiCTR2300072978.</p>

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Distinct SCFA profiles drive contrasting impacts of whole versus refined grains on metabolic health and body composition beyond inflammation in older adults: a secondary analysis of a randomized controlled trial

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月10日

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  • Zhiwen Ge,
  • Cheng Li,
  • Jia Wang,
  • Bingjie Ding,
  • Yaru Li,
  • Nan Wang,
  • Yanxia Bi,
  • Yuxia Wang,
  • Yisi Wang,
  • Zebin Peng,
  • Xinli Yang,
  • Congcong Wang,
  • Zhongxin Hong

摘要

Background

Although whole grains (WG) are widely recommended for health, the divergent impacts of WG versus refined grains (RG) on metabolism, body composition, and inflammation, mediated by distinct short-chain fatty acid (SCFA) profiles, require deeper investigation in older adults. This secondary analysis of a randomized controlled trial aimed to elucidate these differential effects and explore the specific mediating roles of SCFA changes.

Methods

While maintaining their habitual non-staple food intake, 102 participants were randomly assigned to either the WG or RG groups and provided with standardized ingredients for staple food preparation. Fecal SCFAs, blood pressure, blood glucose, renal function markers, body composition, and systemic immune-inflammation markers were assessed at baseline and post-intervention, with further exploration of inter-variable correlations and mediation pathways among these factors.

Results

WG favored butyrate percentage, while RG increased acetate proportion. WG consumption improved post-prandial diastolic blood pressure (DBP), an effect not observed in the RG group, and yielded a significantly greater reduction in serum creatinine. Conversely, RG intake resulted in statistically significant short-term body composition changes, reducing fat mass and increasing lean mass. Mediation analysis revealed that changes in butyrate and acetate acted as suppressors in the pathways linking dietary grain type to post-prandial DBP and blood urea nitrogen changes, respectively. Systemic immune-inflammation markers did not differ between groups.

Conclusion

In our study, we observed that WG and RG consumption elicited distinct SCFA profiles and divergent metabolic and body composition responses in middle-aged and older adults. WG intake preferentially benefited blood pressure and renal function, potentially through SCFA-related pathways, while RG intake unexpectedly improved short-term body composition. These findings highlight the complexity of grain-microbiota-host interactions and suggest that the grain consumed substantially influences metabolic outcomes through SCFA-mediated mechanisms.

Clinical trial registration number: ChiCTR2300072978.