Last week, I discussed the various ways essential oils can inhibit unwanted and resistant microbes. Oregano was one of the highlighted oils due to its ability to prevent microbe biofilm formation, which is a mechanism that critters use to dodge our immune defenses.
After I posted, I felt a little bad not mentioning oregano’s sidekick, thyme. (As you are aware of by now, I have a thing for sidekicks!) As coincidence would have it, I recently got word of Young Living’s February promotion. It includes a unique blend of different species of oregano and my friend, Thymus vulgaris. This gave me good excuse to explore some of thyme’s uses.
Let’s start with the obvious…
In 2010, Science Daily reported that essential oils could be supportive in helping to minimize the risk of antibiotic resistance, highlighting thyme and cinnamon. The following is a summary of these oils’ effects: (1-2)
Essential oils could be a cheap and effective alternative to antibiotics and potentially used to combat drug-resistant hospital superbugs, according to research presented at the Society for General Microbiology’s spring meeting in Edinburgh….
The essential oils of thyme and cinnamon were found to be particularly efficient antibacterial agents against a range of Staphylococcus species. Strains of these bacteria are common inhabitants of the skin and some may cause infection in immunocompromised individuals. Drug-resistant strains, such as meticillin-resistant Staphylococcus aureus (MRSA) are extremely difficult to treat. “Not only are essential oils a cheap and effective treatment option for antibiotic-resistant strains, but decreased use of antibiotics will help minimise the risk of new strains of antibiotic resistant micro-organisms emerging,” said Professor Samaras. (1)
One in vitro study demonstrated that thyme and basil essential oils and their components could decrease concentrations of the unwanted Shigella sp. (This is a good tradeoff for a little brown lettuce in our salad.) (4)
There are a few reports on the antimicrobial activity of essential oils or their major constituents towards Shigella sp. The antimicrobial effect of basil and thyme essential oil and its major constituents thymol, p-cymene, estragol, linalool, and carvacrol was determined using the agar well diffusion assay. Thyme essential oil and thymol and carvacrol showed inhibition of Shigella sp. in the agar well diffusion method. The potential of thyme essential oil, thymol and carvacrol at 0.5% and 1.0% v/v for decontamination of lettuce was evaluated. A decrease of the shigellae was observed after washing with 0.5% while at 1% Shigella numbers dropped below the detection limit. However, the antimicrobial effect on a subsequent lettuce sample in the same decontamination solution was significantly decreased. In addition, application of thyme essential oil or thymol or carvacrol for decontamination is hampered by sensoric properties of the lettuce (browning, strong odour). (4)
Another in vitro study further supported action of thyme and oregano against the foodborne pathogen, E. coli:
Aims: To quantify the antibacterial properties of five essential oils (EO) on a non-toxigenic strain of Escherichia coli O157:H7 in the presence and absence of a stabilizer and an emulsifier and at three different temperatures.
Methods and Results: Five EOs known to exhibit antibacterial properties were screened by disc diffusion assay and the most active were selected for further study in microdilution colorimetric assays. Oregano (Origanum vulgare) and thyme (Thymus vulgaris; light and red varieties) EO had the strongest bacteriostatic and bactericidal properties, followed by bay (Pimenta racemosa) and clove bud (Eugenia caryophyllata synonym: Syzygium aromaticum) EO. Oregano oil was colicidal at 625 ul l–1 at 10, 20 and 37°C. The addition of 0·05% (w/v) agar as stabilizer reinforced the antibacterial properties, particularly at 10°C, whereas 0·25% (w/v) lecithin reduced antibacterial activity. Scanning electron micrographs showed extensive morphological changes to treated cells.
Conclusions: Oregano and thyme EO possess significant in vitro colicidal and colistatic properties, which are exhibited in a broad temperature range and substantially improved by the addition of agar as stabilizer. Bay and clove bud EO are less active. Lecithin diminished antibacterial properties. The bactericidal concentration of oregano EO irreversibly damaged E. coli O157:H7 cells within 1 min.
Significance and Impact of the Study: Oregano and light thyme EO, particularly when enhanced by agar stabilizer, may be effective in reducing the number or preventing the growth of E. coli O157:H7 in foods. (5)
Furthermore, an in vitro study in the International Journal of Food Microbiology suggested components in thyme essential oil have potential to protect against foodborne illnesses passed from animals. This is through their synergistic action in assisting with antibiotic resistant strains:
Plant-derived antibacterial compounds may be of value as a novel means for controlling antibiotic resistant zoonotic pathogens which contaminate food animals and their products. Individual activity of natural antimicrobials (eugenol, thymol, carvacrol, cinnamaldehyde, allyl isothiocyanate (AIT)) and activity when paired with an antibiotic was studied using broth microdilution and checkerboard methods. In the latter assays, fractional inhibitory concentration (FIC) values were calculated to characterize interactions between the inhibitors. Bacteria tested were chosen because of their resistance to at least one antibiotic which had a known genetic basis. Substantial susceptibility of these bacteria toward the natural antimicrobials and a considerable reduction in the minimum inhibitory concentrations (MIC’s) of the antibiotics were noted when paired combinations of antimicrobial and antibiotic were used. In the interaction study, thymol and carvacrol were found to be highly effective in reducing the resistance of Salmonella Typhimurium SGI 1 (tet A) to ampicillin, tetracycline, penicillin, bacitracin, erythromycin and novobiocin (FIC < 0.4) and resistance of Streptococcus pyogenes ermB to erythromycin (FIC < 0.5). With Escherichia coli N00 666, thymol and cinnamaldehyde were found to have a similar effect (FIC < 0.4) in reducing the MIC’s of ampicillin, tetracycline, penicillin, erythromycin and novobiocin. Carvacrol, thymol (FIC < 0.3) and cinnamaldehyde (FIC < 0.4) were effective against Staphylococcus aureus blaZ and in reducing the MIC’s of ampicillin, penicillin and bacitracin. Allyl isothiocyanate (AIT) was effective in reducing the MIC of erythromycin (FIC < 0.3) when tested against S. pyogenes. Fewer combinations were found to be synergistic when the decrease in viable population (log DP) was calculated. Together, fractional inhibitory concentrations <0.5 and log DP < – 1 indicated synergistic action between four natural antimicrobials and as many as three antibiotics to which these bacteria were normally resistant. (6)
Finally, another food safety aspect of thyme essential oil was shown in vitro. Thyme was shown to inhibit oxidation of sunflower oil related to its antioxidant properties. (9)
A small, two-arm, randomized, double-blinded study in Ethiopia with 10 subjects demonstrated the potential of thyme oil’s beneficial effects on eczema-like lesions and fungus on the skin.
Background: Skin diseases are very common in rural and urban areas of Ethiopia, and traditional preparations of plant origin might represent the only alternative to synthetic drugs. Improving knowledge of traditional medicines and assessing their safety and effectiveness is necessary.
Methods: We conducted a two-arm, randomized, double-blind, placebo-controlled trial assessing the efficacy of some cosmetic herbal preparations for common dermatologic problems: a 3% thyme essential oil antifungal cream and a 10% chamomile extract cream for eczema-like lesions.
Results: Ten subjects (66.5%) treated with the 3% thyme active cream were completely healed vs. four subjects (28.5%) from the placebo group (P = 0.040). A large number of subjects treated with the chamomile cream were healed or improved, but no significant differences were found between active cream and placebo. A high rate of treatment acceptance was registered in both groups, no adverse effects were reported.
Conclusions: A 3% thyme essential oil cream could represent a cheap and easily available opportunity to treat and heal mild to moderate cases of fungal infections; a common emollient cream could be a very effective intervention when treating mild to moderate cases of pityriasis alba and eczema-like lesions. Further research is needed. (10)
An in vitro study also tested thyme essential oil’s ability to influence the fungus, Candida albicans. The study evaluated activity in reference to a type of human white blood cell in yeast cells and in vitro (on agar plates) verses a control. The results demonstrated that thyme oil may have a more potent effect on this fungus through modulating these immune cells verses simply inhibiting it on agar plates:
The essential oils have started to be recognized for their potential antimicrobial role only in recent years. Clinical experience showed that the efficacy of antimicrobial agents depends not only on their direct effect on a given microorganism but also on the functional activity of the host immune system. Since data on the effects of essential oils on the innate immune system are scanty and fragmentary, the aim of this study was to evaluate the influence of thyme (red) essential oil (EO), at subinhibitory/inhibitory concentrations, on intracellular killing activity by human polymorphonuclear granulocytes (PMNs) against Candida albicans. In order to provide a frame of reference for the activity of this EO, its in vitro killing activity in the absence of PMNs was also evaluated.
Results showed that EO at subminimal inhibitory (subMIC)/minimal inhibitory (MIC) concentrations significantly enhanced intracellular killing of C. albicans in comparison with EO-free controls and was comparable to the positive control (fluconazole). In in vitro killing assays without PMNs, we observed progressive growth of the yeast cells in the presence of EO subMIC/MIC concentrations. A positive antifungal interaction with phagocytes could explain why this EO, which appeared to be only fungistatic in time-kill assays, had efficacy in killing yeast cells once incubated with PMNs. (11)
Studies On Different Species Of Thyme Essential Oil
Different species of an essential oil contains different active constituents. However, because they all belong to the same family they share similar properties. Some aromatherapists use different species and chemotypes (predominant constituents in the oil) to optimize effects, depending on the situation. These are some studies I ran across on different thyme species:
- One on a different species of thyme and its activity against the tiger mosquito:
Chemical Composition, Larvicidal Action, and Adult Repellency of Thymus magnus Against Aedes albopictus. Journal of the American Mosquito Control Association. 28(3):192-198. 2012 doi:http://dx.doi.org/10.2987/12-6250R.1.
- A rodent study on the effect of thyme on blood pressure:
Antioxidant and Antihypertensive Activity of Extract from Thymus serpyllum L. in Experimental Hypertension. Plant Foods for Human Nutrition. September 2013. http://link.springer.com/article/10.1007/s11130-013-0368-7
- An in vitro study on colon cancer cells using Thymus mastichina:
Thymus mastichina: chemical constituents and their anti-cancer activity. Nat Prod Commun. 2012 Nov;7(11):1491-4. Accessed October 17th 2013.
- An in vitro study on the epigenetic effect on cellular signaling using Thymus serpyllum:
Effects of Thymus serpyllum Extract on Cell Proliferation, Apoptosis and Epigenetic Events in Human Breast Cancer Cells. Nutrition and Cancer. 2012. DOI:10.1080/01635581.2012.719658.
Summary On Thyme
Thyme essential oil may be an overlooked sidekick to oregano for those who are looking to modulate their immune response and inhibit unwanted critters. It may also be a good oil to sprinkle on any food that has questionable freshness when traveling. Below I list some more references on some different species of thyme and the effect of this oil on immune modulation and overall wellness
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Disclaimer: This information is applicable ONLY for therapeutic, Grade A essential oils. This information DOES NOT apply to essential oils that have not been AFNOR and ISO standardized. There is no quality control in the United States and oils labeled as “100% pure” need only contain 5% of the actual oil. The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin.
This information is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness.
(1) Society for General Microbiology. Essential oils to fight superbugs. ScienceDaily. April 4, 2010. www.sciencedaily.com/releases/2010/03/100330210942.htm
(2) Society for General Microbiology. Top microbiology experts meet in Edinburgh at SGM Spring Conference 2010. EurekAlert.com. March 22, 2010. http://www.eurekalert.org/pub_releases/2010-03/sfgm-tme032210.php
(3) The antimicrobial activity of thyme essential oil against multidrug resistant clinical bacterial strains. Microb Drug Resist. 2012 Apr;18(2):137-48. doi: 10.1089/mdr.2011.0080. Epub 2011 Nov 21.
(3) Inhibitory effect of thyme and basil essential oils, carvacrol, thymol, estragol, linalool and p-cymene towards Shigella sonnei and S. flexneri. Food Microbiology. 2004. doi:10.1016/S0740-0020(03)00046-7
(4) Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7. Letters in Applied Microbiology. 2003; 36: 162–167. doi: 10.1046/j.1472-765X.2003.01285.x
(5) What are the benefits of thyme? Medical News Today. September 9, 2014. http://www.medicalnewstoday.com/articles/266016.php
(6) Use of natural antimicrobials to increase antibiotic susceptibility of drug resistant bacteria. International Journal of Food Microbiology. 2010. doi:10.1016/j.ijfoodmicro.2010.04.001
(7) The effectiveness of peppermint and thyme essential oil mist in reducing bacterial contamination in broiler houses. Poult Sci. 2013 Nov;92(11):2834-43. doi: 10.3382/ps.2013-03147.
(8) Vapor-phase activities of cinnamon, thyme, and oregano essential oils and key constituents against foodborne microorganisms. J Agric Food Chem. 2007 May 30;55(11):4348-56. Epub 2007 May 8.
(9) Antioxidative effect of thyme (Thymus vulgaris) in sunflower oil. Acta Sci.Pol., Technol. Aliment. 2012, 11 (3), 283-291. http://www.food.actapol.net/pub/8_3_2012.pdf
(10) Researching accessible and affordable treatment for common dermatological problems in developing countries. An Ethiopian experience. International Journal of Dermatology. 2012; 51: 790–795. doi: 10.1111/j.1365-4632.2011.05235.x
(11) Positive Interaction of Thyme (Red) Essential Oil with Human Polymorphonuclear Granulocytes in Eradicating Intracellular Candida albicans. Planta Med. 2012; 78(15): 1633-1635. DOI: 10.1055/s-0032-1315153.
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