“Essential oils are popular aromatics for scenting a space or setting a mood, but they can be so much more beneficial to our health.” - Amy Leigh Mercree
Introduction | Immune Function | Anti-inflammatory | Antimicrobial | Antioxidant | Anxiolytic | Sleep | Pain Management | Final Thoughts | References | Disclaimer
Introduction
The use of essential oils is strongly associated with alternative and holistic medicine, which tends to utilize naturally available remedies and ingredients as part of the treatment process. Essential oils are highly concentrated plant-derived essences that possess all of the properties of the plant. This is what makes them so powerful and effective in addressing different health issues. Their most common and most investigated application method is aromatherapy. However, essential oils can also be applied to the skin and even ingested.
Essential oils stimulate immune function
Essential oils have potent immunostimulatory and immunomodulatory effects. Their plant-derived components have been found to boost certain immune functions that help combat viral, bacterial, and fungal infections. Among the most common immunity boosters are lavender EO, clove EO, and eucalyptus EO. However, laboratory research has revealed other essences that possess similar properties.
A review of science conducted by Peterfalvi et al.[1] looked at the immunomodulatory effects of essential oils. The authors analyzed a wide variety of research, including in vitro and in vivo animal studies, preclinical trials, and human studies. They found evidence showing that such essential oils as lavender EO, ginger EO, citrus [lemon, bergamot, and orange] EOs, thyme EO, clove EO, eucalyptus EO, and frankincense EO possessed immunomodulatory effects and stimulated the cellular responses of monocytes/macrophages, neutrophil granulocytes, NK cells, and T and B lymphocytes.
Another review carried out by Sander, Heckmann, and Weghuber[2] investigated the effects of lavender, tea tree, eucalyptus, and clove essential oils on different immune functions in the body. They found that lavender EO stimulated the activity of macrophages and decreased bacterial replication within cells. Tea tree EO triggered the maturation of myelocytes into their active monocytic form. Clove EO was found to stimulate immune cells and restore the total white blood count. Lastly, eucalyptus EO stimulated the activity of macrophages and monocytes and boosted bacterial clearance.
Anti-inflammatory properties of essential oils
The anti-inflammatory properties of essential oils have piqued scientists' interest in recent years. The investigation of their composition, effectiveness, and possible applications has shed new light on how they work and how we can benefit from their use.
A study designed by da Silva et al.[3] investigated the effect of lavender essential oil [LEO] on inflammatory processes induced in lab rats. The scientists observed that LEO was able to reduce the inflammatory response [decreased production of cytokines, prostaglandins, and leukotrienes] caused by the administration of carrageenan and croton oil.
A review of science carried out by Borges et al.[4] aimed at analyzing the effects of rosemary essential oil on inflammation. The researchers identified three compounds [1,8-cineole, α-pinene, and camphor] that showed anti-inflammatory attributes and tested them in acute inflammatory conditions. They observed that the anti-inflammatory effects of ROE are due to its ability to inhibit NF-κB transcription and suppress the arachidonic acid cascade. In addition, ROE is a safer anti-inflammatory remedy than many drugs because it does not irritate the digestive tract.
Another study conducted by Boukhatem et al.[5] evaluated the anti-inflammatory properties and effectiveness of lemon grass essential oil [LGEO]. In carrageenan-induced edema, LGEO after 240 minutes of administration showed a 96.8% decrease in skin edema in comparison to the 88.8% reduction achieved by the drug diclofenac. Furthermore, LGEO reduced inflammatory symptoms in ear edema induced by croton oil by 65.2% when compared to diclofenac by 56.2%. This led the authors to conclude that LGEO can be an effective remedy for the treatment of inflammatory skin conditions.
Plant essences and their antimicrobial effects
Numerous scientists have looked into the antimicrobial properties of essential oils and tested different plant essences against various bacterial and fungal strains to determine their efficacy and potential applications. While individual compounds found in every essence can fight off pathogens, the synergistic effect of these components plays an important role in how effective and successful they are.
A study designed by Boruga et al.[6] investigated the antimicrobial effects of thyme essential oil. The scientists tested its effect on six strains of bacteria and a fungus: Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Candida albicans. The results of the tests revealed that TEO successfully inhibited the growth of all bacteria and the fungus. It was noted that the bigger the amount of essential oil [μL = 5, 10, 15, and 20] used, the wider the inhibition zone in the petri dish was.
Another laboratory test conducted by Rezzoug et al.[7] focused on the properties of basil and thyme essential oils. The researchers looked at how these essences and their ethanolic extracts [EE] affected eight types of bacteria and two types of fungi. These were Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida glabrata, and Candida albicans. They found that thyme and basil essential oils showed stronger antibacterial effects than their ethanolic extracts. On the other hand, both EO and EE showed similar antifungal activity.
Lastly, a study carried out by Radünz et al.[8] looked at the antimicrobial activity of clove essential oil [CEO]. The scientists tested CEO properties on such bacterial strains as S. aureus, E. coli, L. monocytogenes, and S. Typhimurium. They found that clove not only inhibited bacterial growth but also had bactericidal effects. Furthermore, this study revealed that clove EO showed stronger antibacterial activity on S. aureus than nitrite.
Antioxidant properties of essential oils
Free radicals are damaging to our bodies and can contribute to the occurrence of disease. Antioxidants such as vitamin C or vitamin E are very effective in combating free radicals and oxidative stress. Scientists have turned their attention to plant-derived essential oils to find out which essences and their components show antioxidant properties and how to use them to our advantage.
A study designed by Rašković et al.[9] looked at the antioxidant activity of rosemary essential oil [REO]. The researchers conducted a DPPH free radical scavenging test, which showed that ROE has a very high free radical scavenging effect [IC50 value of 77.6 μl/ml]. In comparison, tocopherol, which is considered a powerful antioxidant, scored an IC50 value of 25.3 μg/mL.
Another study, carried out by Aldosary et al.[10], focused on the analysis of the antioxidant activity of thymus essential oil [TEO]. The DPPH free radical scavenging test was used to assess the effectiveness of TEO. The analysis revealed that the EO's concentrations of 500 and 1000 ug/ml showed the highest antioxidant activity of 87.3, 88.5 µg/ml, and 96.1, 97.2 µg/ml, respectively.
Lastly, the article presented by Li et al.[11] investigated the free radical scavenging of five citrus EOs: grapefruit essential oil [GEO], sweet orange EO [SEO], bergamot EO [BEO], lemon EO [LEO], and their active component d-limonene EO [DLEO]. At concentrations of 112 and 144 mg/mL in the DPPH test, lemon EO had the highest score [P < 0.05], followed by bergamot EO, sweet orange EO, d-limonene EO [DLEO], and grapefruit EO [lowest score]. Also, the antioxidant activity of citrus essential oil was checked with the ABTS free radical scavenging assay. The results revealed that LEO and DLEO showed the strongest activity in the highest concentrations [32 and 64 mg/ml]. The summary of the results pointed to the overall conclusion that lemon EO is the most potent antioxidant in this group.
Plant-derived essences for anxiety
The anxiolytic effects of essential oils have been investigated for some time now. Essences such as lavender (Lavandula angustifolia), rose (Rosa damascena), orange (Citrus sinensis), bergamot (Citrus aurantium), lemon (Citrus limon), sandalwood (Santalum album), clary sage (Salvia sclarea), Roman chamomile (Anthemis nobilis), and rose-scented geranium (Pelargonium spp.)[14] have been shown to influence anxiety and reduce its effects.
A randomized controlled trial conducted by Zamanifar et al.[12] inspected the effects of lavender-chamomile EO on anxiety levels among nurses. At baseline, the lavender-chamomile EO intervention group measured a standard deviation of 58.20 and a mean of ±15.02; at post-intervention, it measured 37.82±8.79, resulting in a reduction of anxiety by 19.03±12.25. Comparatively, the control group showed a decrease in anxiety of 6.33±14.84. The scientists concluded that such a non-pharmacological approach was successful in significantly reducing anxiety levels among nurses.
Another review of research carried out by Lopez et al.[13] examined the anxiolytic effects of lavender EO. Scientists found evidence that LEO's ability to calm people down is due to its two main ingredients, linalool and linalyl acetate. Both of these monoterpenes interact with the NMDA receptors, which are associated with anxiety-like behavior. Linalool and linalyl acetate were both found to bind with NMDA receptors and therefore influence anxiety.
Essential oils and sleep
According to research, essential oils such as peppermint, lavender, and tangerine have proven to be effective mediators of healthy sleep. They have been found to induce sleep, improve its quality, and impact brain wave power.
A study designed by Hamzeh, Safari-Faramani, and Khatony[15] investigated the impact of aromatherapy with lavender and peppermint essential oils on sleep quality in cancer patients. The scientists evaluated sleep quality before and after the intervention in three groups: the lavender EO group, the peppermint EO group, and the control group. The results revealed that lavender EO and peppermint EO were effective in improving sleep by [p=0.190] and [p=0.280], respectively, in comparison to the controls.
Another study, carried out by Chandharakool et al.[16], looked at the effects of tangerine EO on brain waves and sleep onset latency. After a series of analyses, the researchers found evidence showing that different concentrations of tangerine EO have different effects on the brain. The concentrations of 1:8000 [subthreshold] stimulated the brain by reducing the slow and fast alpha wave powers and by increasing the low beta and mid beta wave powers. At concentrations of 1:1000 [threshold], TEO's effect on the brain was sedative, which was shown by the decrease of alpha and beta wave powers. Additionally, the threshold concentration of TEO was positively associated with the reduction of sleep onset latency.
Pain management with essential oils
Natural ways of relieving pain are interesting and sought-after alternatives to traditional pharmacological products. Essential oils have been shown to possess analgesic properties that can help reduce the severity of pain and shorten its duration.
A systematic review conducted by Tabatabaeichehr and Mortazavi[17] focused on the effects of aromatherapy on labor pains in women. The researchers reported that lavender, Damascus rose, Roman chamomile, peppermint, bitter orange, frankincense, clove, and Mandarin orange essential oils showed significant improvement in labor pains. In contrast, jasmin, geranium, and sweet orange essential oils received mixed results in the pain management test.
A clinical trial designed by Ou et al.[18] looked at the effectiveness of a blend of essential oils consisting of lavender, clary sage, and marjoram on menstrual cramps. The scientists recruited 48 women, who were divided into intervention and control groups. The results of the study revealed that the intervention group experienced a reduction in pain and its duration [from 2.4 days to 1.8 days]. It has been established that the analgesic properties of this blend can be attributed to the following constituents: linalyl acetate, linalool, eucalyptol, and β-caryophyllene.
Final Thoughts
Essential oils are very popular among their enthusiasts. Due to their composition and the variety of phytochemicals they contain, these plant-derived essences find their applications in various health conditions, including both mental and physical ailments. In addition to their anti-inflammatory, antimicrobial, antioxidant, analgesic, anxiolytic, sedative, and immunostimulatory properties, essential oils also possess a wide range of other properties. Science has not yet been able to investigate all of their attributes. However, people who have used them for many years report on the variety of effects they have on the human body and mind. One very important thing to remember is that essential oils are highly concentrated and need to be diluted before use. Furthermore, they can cause a variety of side effects[19], including skin irritations, allergic reactions, and hormonal changes.
References
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