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Your sense of smell can influence your gut health! Inhaling certain essential oils, like peppermint or lemon, can stimulate the vagus nerve, which plays a key role in the gut-brain axis. This connection means that the right scents might help ease digestive discomfort and improve overall gut function.

Essential Oils

Researched by:

Divine Aleru ID

Divine Aleru

I am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.

May 2, 2025

Essential oils are powerful natural substances that can modulate the gut microbiome, offering therapeutic benefits such as enhanced digestion, reduced inflammation, and improved immune function. With antimicrobial properties that selectively target harmful bacteria while promoting beneficial gut microbes, Os like oregano, tea tree, and peppermint are emerging as effective interventions for optimizing health. However, safe application is crucial to avoid potential risks, including skin irritation and interactions with medications. Understanding the proper use of Os ensures their effectiveness in supporting a balanced microbiome and overall well-being.

Research feed

Divine Aleru

I am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.

Researched by:

Divine Aleru ID

Divine Aleru

I am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.

Last Updated: May 2, 2025

Overview

Essential oils are complex mixtures of volatile compounds extracted from plants, including terpenes, phenolics, and aldehydes, which confer biological activities. They have traditionally been used for their aromatic and medicinal properties, but recent attention has shifted towards their ability to modulate gut microbiota.^[1][2] The gut microbiome’s balance is critical for optimal health, making interventions that positively influence its composition particularly attractive. The human microbiome, particularly the gut microbiota, plays a crucial role in health by influencing digestion, immunity, and mental wellbeing. Emerging research highlights essential oils (EOs) as promising microbiome-targeted interventions due to their potent antimicrobial and anti-inflammatory properties.

Mechanism of Action

Essential oils contain numerous bioactive constituents which possess diverse biological activities. These compounds can interact directly with microbial cell membranes, disrupting their integrity through increased permeability and leakage of vital cellular components, ultimately leading to microbial death. Certain EOs exhibit selective antimicrobial effects by preferentially targeting pathogenic bacteria while minimally affecting beneficial species such as Lactobacillus and Bifidobacterium.^[3] EO constituents such as thymol, carvacrol, and eugenol have demonstrated potent antimicrobial effects through mechanisms including interference with microbial enzyme systems and alteration of ion gradients and membrane potentials, thereby impairing cellular metabolism and viability.^[4]

What is the mechanism of action of Essential Oils?

Action	Bioactive Compounds Involved	Mechanism
Cell Membrane Disruption	Thymol, Carvacrol, Eugenol	EOs like thymol, carvacrol, and eugenol have hydrophobic properties that enable them to integrate into microbial cell membranes. This integration alters membrane structure, increases permeability, and leads to leakage of intracellular components, thereby compromising the integrity of the microorganisms and resulting in their death.^[5]
Inhibition of Biofilm Formation	Tea Tree Oil, Oregano	Biofilms are clusters of microorganisms that are bound together by a protective matrix, making them more resistant to antimicrobial agents. EOs like tea tree oil and oregano can disrupt biofilm formation by interfering with microbial communication and adhesion, reducing the ability of pathogenic bacteria to form protective barriers.^[6]
Antioxidant Activity	Lemon, Lavender, Bergamot	EOs with antioxidant properties, such as lemon, lavender, and bergamot, neutralize free radicals. This reduces oxidative stress in gut cells and creates an environment conducive to beneficial bacteria, potentially helping to restore a balanced microbiome.^[7]
Anti-inflammatory Activity	Ginger, Clove, Lavender	Inflammatory cytokines play a significant role in dysbiosis and gut-related diseases. EOs like ginger and clove act by inhibiting pathways such as NF-kB, which leads to a reduction in inflammation. This action helps in maintaining the integrity of the gut lining and supports the healthy functioning of the microbiome.^[8]
Gut Microbial Composition Shift	Peppermint, Oregano, Rosemary	EOs like peppermint and oregano can significantly influence gut microbial composition by promoting the growth of beneficial bacteria, such as Lactobacillus and Bifidobacterium. These bacteria are associated with maintaining a balanced gut microbiome, while EOs suppress pathogenic species such as E. coli.^[9]
Enzyme Inhibition	Eucalyptus, Thyme	Certain EOs inhibit microbial enzymes necessary for pathogen survival. For example, eucalyptus and thyme oils inhibit proteases and lipases, which are involved in the breakdown of proteins and lipids in bacteria. By impeding these enzymes, EOs reduce microbial growth and survival, promoting a healthier gut environment.^[10]

Clinical Evidence

Animal studies consistently support the microbiota-modulating potential of EOs. For instance, supplementation with oregano and thyme oils in animal feed demonstrated significant reductions in pathogenic bacteria, such as Salmonella and E. coli, while simultaneously increasing beneficial gut bacteria.^[11] Similarly, ginger and citral oils have shown beneficial effects in murine models by alleviating inflammation-associated dysbiosis, thereby reducing disease severity in models of colitis and metabolic syndrome.^[12] Humanized mouse models further support these findings. In these studies, human gut microbiota transplanted into mice showed marked improvements in gut health markers following EO supplementation, notably increased production of beneficial metabolites like short-chain fatty acids (SCFAs) and reduced pro-inflammatory cytokine levels.^[13]

Clinical studies remain limited but promising. Preliminary clinical trials have reported beneficial effects of peppermint and oregano oils on gut microbial composition, gastrointestinal discomfort, and symptoms of functional gastrointestinal disorders. These studies suggest potential therapeutic implications in managing digestive disorders through microbiome modulation.^[14]

Potential Health Applications

Essential oils represent a novel and promising approach to microbiome-targeted interventions, demonstrating significant potential across metabolic, inflammatory, and neurological health domains. Comprehensive mechanistic understanding, coupled with expanded clinical research, is essential for the effective translation of EO therapies from experimental contexts into clinical practice.

Application	Effect on Health	Mechanism of Action
Metabolic Disorders	Improves insulin sensitivity, reduces blood glucose, and lowers obesity-associated inflammation	These EOs interact with gut microbiota, promoting the growth of beneficial species, Lactobacillus and Bifidobacterium, which help regulate metabolic functions and reduce inflammation. Oregano and cinnamon also have direct anti-inflammatory effects through modulation of cytokine release, while ginger can lower blood glucose through insulin sensitivity mechanisms.^[15][16]
Inflammatory Bowel Diseases (IBD)	Reduces gut inflammation, restores microbial balance, strengthens gut barrier integrity	EOs like lavender and ginger exhibit anti-inflammatory properties by modulating inflammatory cytokine pathways, while also strengthening the intestinal barrier by promoting the production of mucins and improving epithelial cell integrity. These actions help reduce gut inflammation and dysbiosis.^[17]
Neurological and Mental Health Disorders	Reduces anxiety, improves cognitive function, reduces stress and depression	These EOs can reduce central nervous system inflammation by modulating cytokines and neurotransmitters such as serotonin and GABA, which regulate mood and anxiety. Lavender, for example, influences the hypothalamic-pituitary-adrenal (HPA) axis, reducing cortisol levels. The microbiota-gut-brain axis also plays a role, where EOs modulate gut microbiota to affect brain function.^[18][19]
Infections	Antibacterial, antifungal, and antiviral properties	EOs like tea tree oil exhibit potent antibacterial properties by disrupting bacterial cell membranes, inhibiting cell wall synthesis, and preventing biofilm formation. Oregano and thyme oils also display strong antifungal and antiviral activity through enzyme inhibition and membrane disruption. These effects help combat infections, especially in the gut and respiratory system.^[20][21][22]

Dosage and Safety

The therapeutic application of essential oils necessitates careful consideration of dosage, purity, route of administration, and potential interactions with medications or preexisting health conditions. Oral administration of EOs poses greater risks of gastrointestinal irritation, toxicity, and systemic effects compared to topical or inhalation methods. Therefore, EOs should be administered under professional guidance, adhering strictly to dosage recommendations to mitigate adverse effects.^[23] Quality and purity remain critical factors; the biological effects of EOs can significantly vary depending on extraction methods, storage conditions, and plant origin. Individual variability in microbiome composition and host responses further underscores the need for personalized approaches when integrating EOs into health interventions.

FAQs

How do essential oils function as microbiome-targeted interventions, and can they be considered a natural alternative for health optimization?

Essential oils (EOs) function as microbiome-targeted interventions by influencing the balance of gut bacteria through their antimicrobial and anti-inflammatory properties. EOs like oregano, tea tree, and peppermint can selectively inhibit harmful microbes while promoting the growth of beneficial bacteria such as Lactobacillus and Bifidobacterium. They achieve this by disrupting microbial cell membranes and reducing inflammation in the gut, which helps maintain a healthy microbiome. This modulation of the microbiota supports digestive health, immune function, and even mental well-being via the gut-brain axis, making essential oils a promising natural alternative for health optimization.

re there any hidden dangers or misconceptions when using essential oils for microbiome modulation, and how can we ensure their safe application?

While essential oils (EOs) offer powerful benefits for microbiome modulation, there are potential risks and misconceptions associated with their use. The belief that EOs are completely safe due to their natural origin is misleading; they are highly concentrated and can cause adverse reactions, especially if not properly diluted. Undiluted oils may irritate the skin or digestive system, and some oils, like rosemary or basil, can be harmful during pregnancy. Furthermore, not all EOs are of the same quality, and those with synthetic additives can cause unwanted effects. To ensure safety, it is essential to use high-quality, pure EOs, follow recommended dilution ratios, and consult healthcare professionals, particularly when combining them with other medications or in vulnerable populations. Proper use, along with awareness of their potency and potential interactions, can allow EOs to be a safe and effective tool for microbiome modulation.

Research Feed

October 23, 2024

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What was reviewed?

This review systematically evaluated the role of essential oils (EOs) in improving broiler chickens' health, gut microbiota, and production outcomes. By analyzing 158 publications, it explored the antimicrobial, antioxidant, and growth-promoting properties of EOs sourced from a wide range of plants such as Origanum, Cymbopogon, Citrus, and Eucalyptus. The focus was on how these plant-derived compounds influence gut microbiota composition, inhibit pathogenic bacteria, and serve as sustainable alternatives to antibiotics in poultry farming. The review also detailed various modes of action, including nutrient absorption enhancement, immune system fortification, and oxidative stress reduction, positioning EOs as a promising tool for sustainable broiler production.

Who was reviewed?

The review focused on studies investigating broiler chickens, specifically those examining the effects of dietary or water supplementation with essential oils. It addressed different microbial communities within the chicken gut, noting common bacterial families such as Lachnospiraceae, Ruminococcaceae, and Veillonellaceae, and pathogens like Escherichia coli, Salmonella spp., and Clostridium perfringens. The review highlighted how EOs influenced these microbiota and the overall health and productivity of broilers.

What were the most important findings?

The review found that essential oils exert significant antimicrobial activity, especially against pathogens like E. coli, Klebsiella pneumoniae, Salmonella spp., and Staphylococcus spp. For example, cinnamaldehyde from cinnamon bark and compounds from Cymbopogon citratus were highly effective in reducing pathogenic bacterial loads, improving intestinal morphology, and promoting a healthier gut environment. Origanum EO not only enhanced gut health but also demonstrated strong antioxidant effects, while Citrus oils showed dual benefits of microbial control and reduction of Eimeria oocysts. Importantly, the use of EOs led to improvements in nutrient absorption through enhanced gut morphology, specifically increasing villi height and enzyme activity, thereby boosting growth performance. These findings emphasize the potential of EOs to rebalance gut microbial populations toward beneficial species like Lactobacillus, reduce pathogenic colonization, and serve as natural growth promoters.

What are the greatest implications of this review?

The review underscores that essential oils can act as sustainable and effective alternatives to antibiotics in poultry production. Their ability to reduce pathogenic bacteria while supporting beneficial gut microbiota is critical in addressing antibiotic resistance issues. The implications extend to safer poultry products for consumers and better environmental outcomes. However, the review also highlighted the need for further research to standardize EO formulations, determine optimal dosages, and assess long-term safety for both animals and humans. The findings encourage poultry producers to consider EOs as part of integrated gut health management strategies that align with global moves toward antibiotic-free animal farming.

July 29, 2022

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What was studied?

This experimental study investigated the antibacterial properties of essential oils (EOs) and their effects on growth performance, intestinal morphology, antioxidant capacity, and gut microbiota of yellow-feathered broilers. A total of 720 male chicks were divided into four groups receiving different EO doses over 48 days. The study aimed to determine whether EOs could inhibit bacterial proliferation, improve gut health, and enhance overall poultry production performance. The researchers combined in vitro antimicrobial testing with in vivo assessments of intestinal structure, biochemical markers, and gut microbial shifts.

Who was studied?

The study focused on yellow-feathered broiler chickens, which are commonly used in poultry farming. These birds were fed either a control diet or diets supplemented with varying concentrations of EOs, which contained thymol and carvacrol as active ingredients. Their growth, intestinal morphology, antioxidant responses, serum biochemistry, and cecal microbiota were closely monitored. The microbial focus included pathogenic species like E. coli and Salmonella, along with beneficial genera such as Lactobacillus and Faecalibacterium, enabling a clear view of how the EO interventions reshaped gut microbial communities.

What were the most important findings?

The study demonstrated that EOs significantly inhibited the proliferation and biofilm formation of E. coli O78 and Salmonella pullorum, with minimum inhibitory concentrations (MICs. In vivo, EO supplementation enhanced average daily gain (ADG) and feed efficiency across multiple growth phases. Antioxidant markers such as superoxide dismutase (SOD) and catalase (CAT) activity improved, while intestinal permeability markers (villus height and tight junction protein expression) were positively affected. Gut microbiota analysis revealed that EO supplementation increased beneficial microbes, particularly Lactobacillus and Faecalibacterium, while reducing harmful genera such as Negativibacillus and Flavonifractor. Notably, the EO400 group showed the highest microbial diversity and upregulated pathways for chemoheterotrophy and fermentation. Correlation analysis linked improved gut microbiota profiles to better growth performance, suggesting that EO-driven microbial shifts were central to the observed production benefits.

What are the greatest implications of this study?

This study provides robust evidence that essential oils can serve as effective natural alternatives to antibiotic growth promoters (AGPs) in poultry farming. By reducing pathogenic bacteria and fostering beneficial microbiota, EOs improve gut health and production performance while mitigating risks associated with antibiotic resistance. The findings are particularly relevant as global regulations increasingly restrict AGP use. However, the dose-dependent effects and variable long-term impacts highlight the need for precise formulation and further research to optimize EO-based interventions in commercial settings.

March 27, 2014

What was reviewed?

This review explored the integral role of the microbiota in the development, calibration, and regulation of the mammalian immune system. It focused on how commensal microbes influence both innate and adaptive immunity, discussing the symbiotic relationship between host and microbiota under normal and pathological conditions. The review synthesized findings on how microbial communities modulate immune responses locally, such as at mucosal surfaces, and systemically, highlighting their involvement in shaping immune tolerance, inflammatory responses, and susceptibility to diseases like autoimmune disorders and infections.

Who was reviewed?

The review concentrated on human and murine models to illustrate the microbiota's effect on immunity. It analyzed how diverse microbial communities impact the immune system from early life to adulthood. The evidence spanned multiple anatomical sites, including the gastrointestinal tract, skin, lungs, and other barrier tissues, recognizing the microbiota’s pervasive presence and its critical influence on immune health across different host organisms.

What were the most important findings?

This review underscored the pivotal role of the microbiota in fine-tuning immune responses at both mucosal and systemic levels. Key findings include the discovery that commensal bacteria act as adjuvants, essential for robust Th1 and Th17 responses, and the identification of "keystone species" such as Segmented Filamentous Bacteria (SFB), which potently stimulate gut immunity by inducing IL-17 and IgA production. Importantly, the review highlighted the microbiota's capacity to maintain immune homeostasis via mechanisms like the production of antimicrobial peptides, strengthening barrier defenses, and training innate immune cells for rapid pathogen response. It also detailed systemic effects, showing that antibiotics or germ-free conditions dampen immune defenses, not only locally but throughout the body, as seen in impaired antiviral responses and tumor control. Additionally, specific commensals like Barnesiella were noted for their protective effects against infections such as vancomycin-resistant Enterococcus and Clostridium difficile, further illustrating the therapeutic potential of microbiome-targeted interventions.

What are the greatest implications of this review?

The findings presented have profound clinical and research implications. They emphasize that disturbances in microbiota composition, due to antibiotics, diet, or other factors, can trigger or exacerbate immune-related diseases, including allergies, autoimmune disorders, and chronic inflammation. The review suggests that microbiota manipulation, through probiotics, fecal microbiota transplants, or diet, offers promising therapeutic avenues for restoring immune balance. It also posits that understanding keystone microbes and their immune-modulating capabilities could revolutionize strategies for vaccine development, cancer immunotherapy, and infection control

May 20, 2023

What was studied?

This study investigated the therapeutic effects and mechanisms of ginger essential oil (GEO) and its active compound, citral, on atherosclerosis progression through modulation of gut microbiota and trimethylamine-N-oxide (TMAO) production. Specifically, the research focused on evaluating how GEO and citral supplementation affected the formation of atherosclerotic plaques, plasma lipid profiles, inflammation markers, glucose and insulin metabolism, and gut microbiota composition in ApoE−/− mice. The mice were fed a high-fat, high-cholesterol Gubra Amylin NASH (GAN) diet supplemented with L-carnitine to induce atherosclerosis.

Who was studied?

The study used female ApoE−/− mice, a genetically engineered model that develops severe hypercholesterolemia and spontaneous atherosclerosis, mirroring cardiovascular disease (CVD) in humans. These mice were subjected to a GAN diet rich in cholesterol, fats, and fructose combined with L-carnitine, which enhanced atherosclerotic plaque formation through elevated production of the pro-atherogenic metabolite, TMAO. The mice were divided into control and experimental groups receiving either a low dose or high dose of GEO or citral daily for 16 weeks.

What were the most important findings?

Significant findings from this study included the ability of both GEO and citral to inhibit the formation of atherosclerotic lesions, reduce plasma levels of cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides, and significantly elevate beneficial high-density lipoprotein cholesterol (HDL-C). GEO and citral effectively reduced plasma levels of TMAO, a known risk factor for CVD, produced via gut microbiota metabolism of dietary L-carnitine. Additionally, GEO and citral treatments improved insulin sensitivity, reduced fasting blood glucose levels, and lowered plasma inflammatory markers such as IL-1β, TNF-α, and IL-6. These anti-atherosclerotic effects correlated with positive modifications in gut microbiota composition; GEO and citral increased beneficial genera such as Akkermansia, Allobaculum, and Dubosiella, while suppressing potentially pathogenic bacteria associated with elevated TMAO production, notably Enterorhabdus, Proteus, and Escherichia-Shigella. Thus, the study provided clear microbial signatures linked with the beneficial outcomes of GEO and citral supplementation.

What are the greatest implications of this study?

The greatest implication of this research is the potential for GEO and citral as dietary interventions or adjunctive therapies to prevent or mitigate cardiovascular disease through gut microbiome modulation. By reducing pathogenic gut microbiota, suppressing the formation of harmful metabolites like TMAO, and significantly improving lipid profiles and inflammation markers, these compounds represent promising candidates for natural, microbiome-targeted preventive strategies in cardiovascular disease management. This insight underscores the value of dietary essential oils in clinical practice and highlights gut microbiome modulation as a significant therapeutic target for atherosclerosis and associated metabolic disorders.

February 10, 2023

What was reviewed?

This review examined scientific evidence regarding the therapeutic effects of essential oils (EOs) on the oral microbiome. It focused on EOs' antibacterial, antimicrobial, antiviral, antifungal, and anti-inflammatory properties, highlighting their potential as alternative therapies in dentistry. The review also considered general properties of EOs, including their chemical compositions, extraction methods, therapeutic applications in dentistry, and potential toxicities.

Who was reviewed?

The review concentrated primarily on common oral pathogens such as Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis, Prevotella intermedia, Enterococcus faecalis, and Candida albicans. Additionally, various essential oils were reviewed, notably Clove, Lavender, Cinnamon, Eucalyptus, Thyme, Tea Tree, and Citrus oils, among others.

What were the most important findings?

The review identified significant therapeutic potential of EOs in dentistry, emphasizing their ability to combat oral pathogens responsible for cavities, gingivitis, periodontitis, and oral cancer. Major microbial associations highlighted include the inhibition of S. mutans and S. sobrinus by Cinnamon and Eucalyptus oils, significant antifungal activity against C. albicans by Clove and Cinnamon oils, and the general antibiofilm effects of Lavender and Lemongrass oils against periodontal pathogens like P. gingivalis. Furthermore, these EOs have demonstrated effectiveness in reducing plaque and gingival inflammation, thus improving oral health. Specific active compounds within these oils, such as thymol, eugenol, cinnamaldehyde, linalool, and pinene, were identified as responsible for their antimicrobial properties. The review also acknowledged the side effects and toxicities of certain essential oils, stressing the need for controlled usage and further clinical evaluations.

What are the greatest implications of this review?

The most significant implication is the potential use of EOs as viable alternatives or adjunctive therapies to traditional antibiotics in dental practice, particularly considering the increasing resistance of oral pathogens to conventional treatments. By integrating EOs into clinical protocols, dentists can offer safer, natural treatment options that mitigate antibiotic resistance, reduce inflammation, and control oral microbial populations. However, the review emphasizes the necessity of extensive clinical trials to confirm the efficacy, safety, and optimal therapeutic concentrations of these oils before their routine clinical application can be fully recommended.

November 3, 2022

What was studied?

This study investigated the beneficial effects of essential oils (EOs) from common Mediterranean diet herbs, specifically savory (Satureja hortensis), parsley (Petroselinum crispum), and rosemary (Rosmarinus officinalis), on gut microbiota and their metabolites in the context of ischemic heart disease (IHD) and type-2 diabetes mellitus (T2DM). The researchers aimed to evaluate how these essential oils, when administered as nutraceutical emulsions, affect gut microbiota composition, plasma metabolites associated with cardiovascular risk, inflammatory biomarkers, and oxidative stress in a humanized mouse model.

Who was studied?

The study used a humanized gnotobiotic mouse model, specifically female CD1 mice, whose gut microbiota had been depleted by antibiotics and then recolonized with microbiota from human patients diagnosed with both IHD and T2DM. After gut microbiota transplantation, the mice were supplemented with L-carnitine to stimulate cardiovascular risk factors and treated orally with emulsions of savory, parsley, or rosemary essential oils for 40 days.

What were the most important findings?

The most critical findings revealed significant beneficial effects of parsley and rosemary essential oils on the gut microbiome and associated metabolites. Treatment with these essential oils significantly increased beneficial gut bacteria, notably the Lactobacillus genus, while decreasing the abundance of less beneficial genera such as Bacteroides. Additionally, parsley and rosemary essential oils notably reduced plasma trimethylamine N-oxide (TMAO), a known cardiovascular risk marker produced by gut microbiota metabolism of L-carnitine. There was also an important increase in short-chain fatty acids (SCFAs), particularly acetic, propionic, and butyric acids, in feces following parsley and rosemary treatments, suggesting enhanced fermentation and gut health. Furthermore, parsley and savory essential oils elevated plasma thrombomodulin levels, potentially indicating improved endothelial function. These oils also demonstrated significant anti-inflammatory properties by reducing cytokines, including IFNγ, TNFα, IL-12p70, and IL-22, which are typically elevated in inflammatory states associated with IHD and T2DM.

What are the greatest implications of this study?

The greatest implications of this study are the potential therapeutic applications of essential oils from savory, parsley, and rosemary as functional nutraceuticals in patients suffering from IHD and T2DM. The demonstrated modulation of gut microbiota towards beneficial profiles, reduction of pro-atherogenic metabolites such as TMAO, increased production of health-promoting SCFAs, and the substantial anti-inflammatory and antioxidant effects underscore these essential oils as promising candidates for complementary or alternative therapeutic strategies to mitigate cardiovascular and metabolic diseases associated with dysbiosis and chronic inflammation.

July 8, 2022

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.

March 18, 2021

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What was reviewed?

The review paper focuses on the contribution of essential oils (EOs) in combating microbial biofilms, with an emphasis on their antimicrobial properties and the potential application in medical, food, and other industrial sectors. The review explores the growing body of scientific data showing the effectiveness of essential oils against biofilms, which are known to contribute to persistent infections, particularly those associated with medical devices and chronic infections. The paper provides an in-depth analysis of several studies that highlight how EOs, through their diverse chemical compositions, possess the ability to disrupt biofilm formation by bacteria and fungi.

Who was reviewed

The review analyzed various scientific literature and research papers that evaluated the effectiveness of essential oils in combating microbial biofilms. The focus was on assessing how different essential oils have antimicrobial properties that can disrupt biofilm formation and enhance the effectiveness of traditional treatments.

What were the most important findings?

The most important finding of this review is the significant role essential oils (EOs) can play in combating microbial biofilms, which are highly resistant to conventional antibiotics. The review outlines various essential oils, such as those derived from Melaleuca alternifolia (tea tree oil), Lavandula angustifolia (lavender oil), and Cinnamomum zeylanicum (cinnamon oil), that have been proven to inhibit or eradicate biofilms. Specifically, the antimicrobial components of EOs, including terpenes and terpenoids, act by permeabilizing bacterial membranes, which makes biofilms more susceptible to antimicrobial treatments. The review emphasizes that these oils not only affect planktonic bacteria but also disrupt biofilms formed on surfaces, which is crucial in the context of medical devices like catheters and prosthetics.

In terms of microbial associations, the review focuses on EOs' efficacy against a range of pathogenic organisms, including Staphylococcus aureus, Escherichia coli, and Candida species. Biofilms formed by these organisms on medical devices are notably resistant to conventional treatments, and the use of EOs could offer a complementary or alternative approach. The synergistic effect of combining EOs with traditional antibiotics is also highlighted, as this combination increases the efficacy of treatment and reduces the chances of biofilm formation.

What are the implications of this review?

The review reveals the potential of essential oils as a safe and effective alternative to conventional antibiofilm agents, particularly for infections related to medical devices, foodborne illnesses, and oral health. The diverse chemical compositions of EOs reduce the likelihood of microbial resistance, a growing concern with traditional antibiotics. Furthermore, the combination of EOs with other antimicrobial treatments offers promising results for tackling biofilm-related infections more effectively. The study suggests that further clinical trials and the optimization of EO formulations are needed to fully harness their potential in combating biofilms, especially in medical and industrial applications. Incorporating EO-based therapies into current infection control practices could help address the persistent problem of biofilm-associated infections, which are difficult to treat with traditional antibiotics alone.

References

Essential Oils, Chemical Compounds, and Their Effects on the Gut Microorganisms and Broiler Chicken Production: Review. Salinas-Chavira, J., & Barrios-García, H. B. (2024). (Agriculture, 14(11), 1864.)
Dietary essential oils improves the growth performance, antioxidant properties and intestinal permeability by inhibiting bacterial proliferation, and altering the gut microbiota of yellow-feather broilers. Ding Y, Hu Y, Yao X, He Y, Chen J, Wu J, Wu S, Zhang H, He X, Song Z.. (Poult Sci. 2022 Nov;101(11):102087)
Dietary essential oils improves the growth performance, antioxidant properties and intestinal permeability by inhibiting bacterial proliferation, and altering the gut microbiota of yellow-feather broilers. Ding Y, Hu Y, Yao X, He Y, Chen J, Wu J, Wu S, Zhang H, He X, Song Z.. (Poult Sci. 2022 Nov;101(11):102087)
Essential Oils, Chemical Compounds, and Their Effects on the Gut Microorganisms and Broiler Chicken Production: Review. Salinas-Chavira, J., & Barrios-García, H. B. (2024). (Agriculture, 14(11), 1864.)
Biological effects of essential oils – A review. Bakkali, F., Averbeck, S., Averbeck, D., & Idaomar, M. (2008). (Food and Chemical Toxicology, 46(2), 446-475)
Dietary essential oils improves the growth performance, antioxidant properties and intestinal permeability by inhibiting bacterial proliferation, and altering the gut microbiota of yellow-feather broilers. Ding Y, Hu Y, Yao X, He Y, Chen J, Wu J, Wu S, Zhang H, He X, Song Z.. (Poult Sci. 2022 Nov;101(11):102087)
The Microbiota-Gut-Brain Axis. Cryan, J. F., M. Cowan, C. S., Sandhu, K. V., S. Bastiaanssen, T. F., Boehme, M., Codagnone, M. G., Cussotto, S., Fulling, C., Golubeva, A. V., Guzzetta, K. E., Jaggar, M., Long-Smith, C. M., Lyte, J. M., Martin, J. A., Molinero-Perez, A., Moloney, G., Morelli, E., Morillas, E., Cruz-Pereira, J. S., . . . Dinan, T. G. (2019). (Physiological Reviews.)
Modulation of Gut Microbiota by Essential Oils and Inorganic Nanoparticles: Impact in Nutrition and Health. Lazar, V., Holban, A., Curutiu, C., & Ditu, L. M. (2022).. (Frontiers in Nutrition, 9, 920413)
Ginger essential oil and citral ameliorates atherosclerosis in ApoE-/- mice by modulating trimethylamine-N-oxide and gut microbiota. Panyod S, Wu WK, Peng SY, Tseng YJ, Hsieh YC, Chen RA, Huang HS, Chen YH, Chuang HL, Hsu CC, Shen TD, Yang KC, Ho CT, Wu MS, Sheen LY.. (NPJ Sci Food. 2023 May 20;7(1):19)
Beneficial Effects of Essential Oils from the Mediterranean Diet on Gut Microbiota and Their Metabolites in Ischemic Heart Disease and Type-2 Diabetes Mellitus. Sánchez-Quintero, M. J., Delgado, J., Medina-Vera, D., Becerra-Muñoz, V. M., Queipo-Ortuño, M. I., Estévez, M., Plaza-Andrades, I., Rodríguez-Capitán, J., Sánchez, P. L., Crespo-Leiro, M. G., Jiménez-Navarro, M. F., & Pavón-Morón, F. J. (2022). (Nutrients, 14(21), 4650.)
Modulation of Gut Microbiota by Essential Oils and Inorganic Nanoparticles: Impact in Nutrition and Health. Lazar, V., Holban, A., Curutiu, C., & Ditu, L. M. (2022).. (Frontiers in Nutrition, 9, 920413)
Ginger essential oil and citral ameliorates atherosclerosis in ApoE-/- mice by modulating trimethylamine-N-oxide and gut microbiota. Panyod S, Wu WK, Peng SY, Tseng YJ, Hsieh YC, Chen RA, Huang HS, Chen YH, Chuang HL, Hsu CC, Shen TD, Yang KC, Ho CT, Wu MS, Sheen LY.. (NPJ Sci Food. 2023 May 20;7(1):19)
Revisiting the Therapeutic Effects of Essential Oils on the Oral Microbiome. Radu, C.-M., Radu, C. C., Bochiș, S.-A., Arbănași, E. M., Lucan, A. I., Murvai, V. R., & Zaha, D. C. (2023). (Pharmacy, 11(1), 33.)
Dietary essential oils improves the growth performance, antioxidant properties and intestinal permeability by inhibiting bacterial proliferation, and altering the gut microbiota of yellow-feather broilers. Ding Y, Hu Y, Yao X, He Y, Chen J, Wu J, Wu S, Zhang H, He X, Song Z.. (Poult Sci. 2022 Nov;101(11):102087)
Dietary essential oils improves the growth performance, antioxidant properties and intestinal permeability by inhibiting bacterial proliferation, and altering the gut microbiota of yellow-feather broilers. Ding Y, Hu Y, Yao X, He Y, Chen J, Wu J, Wu S, Zhang H, He X, Song Z.. (Poult Sci. 2022 Nov;101(11):102087)
Beneficial Effects of Essential Oils from the Mediterranean Diet on Gut Microbiota and Their Metabolites in Ischemic Heart Disease and Type-2 Diabetes Mellitus. Sánchez-Quintero, M. J., Delgado, J., Medina-Vera, D., Becerra-Muñoz, V. M., Queipo-Ortuño, M. I., Estévez, M., Plaza-Andrades, I., Rodríguez-Capitán, J., Sánchez, P. L., Crespo-Leiro, M. G., Jiménez-Navarro, M. F., & Pavón-Morón, F. J. (2022). (Nutrients, 14(21), 4650.)
Essential Oils, Chemical Compounds, and Their Effects on the Gut Microorganisms and Broiler Chicken Production: Review. Salinas-Chavira, J., & Barrios-García, H. B. (2024). (Agriculture, 14(11), 1864.)
The Microbiota-Gut-Brain Axis. Cryan, J. F., M. Cowan, C. S., Sandhu, K. V., S. Bastiaanssen, T. F., Boehme, M., Codagnone, M. G., Cussotto, S., Fulling, C., Golubeva, A. V., Guzzetta, K. E., Jaggar, M., Long-Smith, C. M., Lyte, J. M., Martin, J. A., Molinero-Perez, A., Moloney, G., Morelli, E., Morillas, E., Cruz-Pereira, J. S., . . . Dinan, T. G. (2019). (Physiological Reviews.)
Ginger essential oil and citral ameliorates atherosclerosis in ApoE-/- mice by modulating trimethylamine-N-oxide and gut microbiota. Panyod S, Wu WK, Peng SY, Tseng YJ, Hsieh YC, Chen RA, Huang HS, Chen YH, Chuang HL, Hsu CC, Shen TD, Yang KC, Ho CT, Wu MS, Sheen LY.. (NPJ Sci Food. 2023 May 20;7(1):19)
Contribution of Essential Oils to the Fight against Microbial Biofilms—A Review.. Nuță, D. C., Limban, C., Chiriță, C., Chifiriuc, M. C., Costea, T., Ioniță, P., Nicolau, I., & Zarafu, I.. (Processes, 9(3), 537. 2021)
Essential Oils as Antiviral Agents. Potential of Essential Oils to Treat SARS-CoV-2 Infection: An In-Silico Investigation. Silva JKRD, Figueiredo PLB, Byler KG, Setzer WN.. (Int J Mol Sci. 2020 May 12;21(10):3426.)
Antifungal Properties of Essential Oils and Their Compounds for Application in Skin Fungal Infections: Conventional and Nonconventional Approaches. Abd Rashed A, Rathi DG, Ahmad Nasir NAH, Abd Rahman AZ.. (Molecules. 2021 Feb 19;26(4):1093)
Biological effects of essential oils – A review. Bakkali, F., Averbeck, S., Averbeck, D., & Idaomar, M. (2008). (Food and Chemical Toxicology, 46(2), 446-475)

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