Dietary Fibre Modulates Gut Microbiota Responses to Copper Nanoparticles

Area of Science:

• * Environmental toxicology and food science research.
• * Investigating nanoparticle interactions within biological systems.

Background:

• * Copper nanoparticles (Cu-NPs) are increasingly used as food and feed additives.
• * Limited understanding exists on how dietary fiber matrices influence Cu-NP effects on gut microbiota.

Purpose of the Study:

• * To evaluate how different dietary fibers (cellulose, pectin, inulin, psyllium) modulate Cu-NP-driven changes in rat caecal microbiota.
• * To assess the impact of fiber type, copper dose, and copper form on gut microbiota activity, composition, and bile acid metabolism.

Main Methods:

• * Wistar male rats were fed semi-purified diets containing Cu-NPs (6.5 or 13 mg Cu/kg) combined with cellulose, pectin, inulin, or psyllium for 6 weeks.
• * Caecal digesta, microbial enzyme activities, short-chain fatty acids (SCFAs), bile acids, and 16S rRNA sequencing were analyzed.

Main Results:

• * Dietary fiber type significantly influenced microbiota composition and bile acid profiles, more so than Cu-NPs alone.
• * Pectin intake was associated with increased SCFA levels, while psyllium reduced total bile acids and inulin increased muricholic acids.
• * Cu-NPs at higher doses reduced microbial enzyme activities and SCFAs, but pectin mitigated some of these effects.

Conclusions:

• * Gastrointestinal and microbiota responses to Cu-NPs are strongly dependent on the dietary fiber matrix.
• * Cu-NP safety and functionality assessments must consider the accompanying fiber, not just the nanoparticles in isolation.
• * Further research in human-relevant models is needed to confirm implications for human health.