High-Fat Diet with Normal Caloric Intake Elevates TMA and TMAO Production and Reduces Microbial Diversity in Rats

Area of Science:

• Microbiology
• Metabolomics
• Nutritional Science

Background:

• Gut microbiota produces trimethylamine (TMA) and trimethylamine N-oxide (TMAO), linked to cardiometabolic diseases.
• The impact of high-fat diets (HFDs) and high-disaccharide diets (HDDs) on TMA/TMAO production under physiological caloric intake is not well understood.

Purpose of the Study:

• To investigate the effects of HFDs and HDDs on gut microbiota composition and TMA/TMAO production in rats at physiological caloric intake.
• To determine how diet composition, independent of caloric excess, influences gut microbiota and cardiometabolic biomarkers.

Main Methods:

• Rats were fed a standard diet, HFD, or HDD for 12 weeks, with caloric intake controlled.
• Gut bacterial diversity was assessed using 16S rRNA gene sequencing.
• Urinary and plasma metabolites (TMA, TMAO) were quantified using HPLC-MS.

Main Results:

• The HFD group exhibited significantly higher urinary TMA and TMAO levels compared to control and HDD groups.
• HFD led to a marked reduction in gut bacterial diversity, including species richness and phylogenetic diversity.
• Specific bacterial taxa (Pasteurellaceae, S24-7) were positively correlated with TMAO levels.
• The HDD group showed increased microbial diversity compared to control and HFD groups.

Conclusions:

• Dietary fat content, not just caloric load, significantly impacts TMA/TMAO production.
• High-fat diets can negatively alter gut microbiota composition and increase cardiometabolic risk factors.
• Understanding diet-microbiota interactions is crucial for managing cardiometabolic health.