Thyme references
Thymus vulgaris 

 The bibliographic citations are derived from Medline databases through the National Library of Medicine.

Effects on bacteria

S Inouye, H Yamaguchi, T Takizawa  (2001). Screening of the antibacterial effects of a variety of essential oils on
respiratory tract pathogens, using a modified dilution assay method.  J Infect Chemother 7(4):251-4.

The antibacterial activity of 14 essential oils and their major components against common respiratory tract bacteria was
studied in the lab. Haemophilus influenzae was the most susceptible to the oils, followed by Streptococcus pneumoniae,
 Streptococcus pyogenes, and Staphylococcus aureus, in that order. No difference in susceptibility was seen between
penicillin-sensitive and penicillin-resistant S. pneumoniae. The highest antibacterial activity was by essential oils
containing aldehydes or phenols. Those  containing terpene ketones (ether) had much weaker action. Those with
terpene hydrocarbons were inactive against all four bacterium. Oils with high aldehyde components-thyme (wild, red,
and geraniol types), cinnamon bark, lemongrass, perilla, and peppermint oils-were chosen for further study.

S Inouye, H Yamaguchi, T Takizawa  (2001). Antibacterial effects of essential oils and their major constituents against
respiratory tract pathogens by gaseous contact. J Antibicrob Chemother 47(5):565-73.

The antibacterial activity of 14 essential oils and their major components in a gaseous state was studied against common
respiratory tract bacteria in the lab. Haemophilus influenzae was the most susceptible to the oils, followed by
Streptococcus pneumoniae,  Streptococcus pyogenes, and Staphylococcus aureus, in that order. Penicillin-susceptible
and -resistant S. pneumoniae were similar in susceptibility. Cinnamon bark, lemon-grass and thyme oils had the strongest
activity, using the smallest concentration of oil to kill the bacteria. Short-term exposure to the vapour was as effective as
overnight exposure. These results indicate that the antibacterial action of essential oils was most effective when at high
vapour concentration for a short time.

HJ Dorman, SG Deans (2000). Antimicrobial agents from plants: antibacterial activity of plant volatile oils. J Appl Microbiol
88(2):308-16.

The effect of essential oils was tested against 25 different genera of bacteria. These included animal and plant pathogens, food
poisoning and spoilage bacteria. The oils tested were black pepper (Piper nigrum ) clove (Syzygium aromaticum),  
geranium([Pelargonium graveolens), nutmeg (Myristica fragrans), oregano (Origanum vulgare ssp.),  and thyme (Thymus
vulgaris L.). All of the whole oils exhibited considerable inhibitory effects against all of the bacteria tested. The major components
of the oils inhibited bacterial growth by varying degrees.

Effects on insects

DR Barnard (1999). Repellancy of essential oils to mosquitoes (Diptera:Culicidae). J Med Entomol 36(5):625-9.

The repellancy of essential oils of Bourbon geranium, cedarwood, clove, peppermint, and thyme were studied against two common
mosquitos. Different concentrations of the oils (5, 10, 25, 50, 75, and 100%) were applied to human skin. None of the oils tested
prevented mosquito bite when used at the 5 or 10% concentration. Thyme and clove oils were the most effective mosquito
repellents and provided 1 1/2 to 3 1/2 h of protection, depending on oil concentration. 50% concentration was needed for
prevention against biting. These oils can be irritating to the skin. Both human subjects in this study also found the odor of
thyme and clove oils unpleasant at 25% concentrations and above.

Effects as a dietary antioxidant 

KA Youdim, SG Deans (1999).  Beneficial effects of thyme oil on age-related changes in the phospholipid C20 and
C22 polyunsaturated fatty acid composition of various rat tissues.  Biochim Biophys Acta 1438(1):140-6.

This study assessed the effects of dietary supplementation (42.5 mg/kg body weight/day) of the natural antioxidant thyme oil and
its major component thymol throughout the rat life span. These results show that dietary supplementation with thyme oil
tended to maintain higher polyunsaturated fatty acid composition levels in all tissues studied (rat liver, brain, kidney and heart).
The majority of protection provided by thyme oil was by virtue of its thymol component, which comprises 49% of the whole oil.
Thymol administered alone did not provide significantly higher protection than the whole oil, suggesting that other components
within thyme oil are also contributing antioxidant activity.

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Last updated 04.14.05