Modulation of Gut Microbiota by Essential Oils and Inorganic Nanoparticles: Impact in Nutrition and Health Original paper

What was reviewed?

This review evaluated recent scientific literature concerning the modulation of gut microbiota by essential oils (EOs) and inorganic nanoparticles (NPs), exploring their potential impacts on human nutrition and health. Specifically, it discussed the interactions among gut microbiota, inorganic nanoparticles, such as silver (Ag), titanium dioxide (TiO₂), zinc oxide (ZnO), and silicon dioxide (SiO₂), and various EOs derived from fruits, herbs, and medicinal plants. The review provided insights into the mechanisms through which EOs and nanoparticles modulate gut microbiota, their metabolic products such as short-chain fatty acids (SCFAs), and implications for gut inflammation and systemic health effects.

Who was reviewed?

The review analyzed evidence from various animal models (rodents and pigs), in vitro bacterial cultures, and selected human studies that examined interactions between gut microbiota and exposure to essential oils or nanoparticles. The organisms primarily considered included common gut bacteria from the Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria phyla, along with pathogenic strains such as Escherichia coli, Clostridium perfringens, Salmonella enterica, and Candida albicans.

What were the most important findings?

The review highlighted essential oils’ potent antimicrobial and anti-inflammatory properties, which can beneficially modulate gut microbiota by reducing pathogenic and inflammatory bacterial populations. Notably, bioactive compounds such as d-limonene, carvacrol, thymol, and various polyphenols exhibited substantial modulation of gut microbial communities, positively influencing gut homeostasis and metabolic health. Essential oils also showed capacity for increasing beneficial bacterial taxa, Lactobacilli, and enhancing SCFA production, critical for maintaining gut integrity and reducing inflammation.

Conversely, inorganic nanoparticles generally induced significant microbiota dysbiosis, characterized by decreased beneficial taxa like Firmicutes and Lactobacilli, and increased pathogenic or pro-inflammatory taxa like Proteobacteria. Specifically, silver and titanium dioxide nanoparticles significantly altered gut microbial balance, increasing gut inflammation and oxidative stress markers, while zinc oxide and silicon dioxide nanoparticles negatively impacted gut microbiota diversity and barrier function at higher exposures. However, nanoparticles could also be beneficial when functionalized with essential oils, demonstrating enhanced antimicrobial effects against pathogens, although their long-term safety profiles remain unclear.

What are the greatest implications of this review?

The greatest implications of this review lie in its recognition of essential oils as promising modulators of gut microbiota, potentially useful in managing gut dysbiosis and inflammatory conditions. Additionally, understanding the detrimental effects of nanoparticles on gut microbiota underscores the need for careful assessment of their dietary and therapeutic applications, particularly considering their prevalence in daily consumer products. Moreover, the potential synergistic or antagonistic interactions between essential oils and nanoparticles could lead to novel therapeutic approaches or unintended health consequences, highlighting an urgent need for further comprehensive research into their combined effects on gut microbiome health.