Wednesday March 28 2012
A thyme extract killed bacteria in a lab, not humans
“Beating acne may be a matter of thyme,” quipped the Daily Mail, adding that an extract of the herb could be more effective than benzoyl peroxide – a chemical found in many anti-acne creams and washes.
These claims are based on laboratory research that tested how well a range of plant extracts can kill the bacteria that cause acne. Most notably, researchers found that an alcohol-based thyme extract could kill the bacteria that caused acne in the laboratory, and at specific concentrations was more effective than benzoyl peroxide. The research has not yet been published but was presented at a conference, which means that few details of its methods and results are available yet. Therefore, the claims should be treated with some caution until they are checked out by experts, which will happen when the research papers are submitted to the full publication process.
While providing an eye-catching news story, there is a long way to go from the initial lab-based results of this study and proving thyme is better at fighting acne or is less harsh on the skin than existing treatments.
Where did the story come from?
The study was carried out by researchers from Leeds Metropolitan University and presented at a Society for General Microbiology conference. The source of funding for this research wasn’t reported in the conference abstract.
As a conference presentation abstract, this research hasn’t been through the full peer-review process yet, as this usually takes place when research is published in journals (articles are reviewed for sense and validity by experts in the field to ensure they are of sufficient quality).
The story was covered by the Daily Mail, The Daily Telegraph and Metro. The Daily Mail story provided a good explanation of what was done in the study, but its headline, suggesting that herbal cream is better than existing treatments, was put more positively than is warranted by this early laboratory research. The Metro version of the story doesn’t make it very clear that this research was done in the lab and not with humans.
What kind of research was this?
The researchers conducting this study said that acne remedies “currently preferred by herbalists” include thyme, marigold and myrrh tinctures, so they used extracts from these plants in the laboratory study. During the research, they looked at the effects these different herbal extracts had on the bacteria that cause acne. The researchers suggested that herbal extracts may have an application in acne treatment as they may be able to reduce “aggravation of the skin” due to their anti-inflammatory and antimicrobial qualities.
Research such as this may indicate that an extract has anti-bacterial properties in the lab, but any promising results would need further testing to see what concentrations of the substances are safe for use on human skin, and whether they can improve acne.
What did the research involve?
Few details of the methods used by the researchers were available from the conference abstract, which instead provided a summary.
In the lab, researchers compared thyme, marigold and myrrh tinctures against benzoyl peroxide – a chemical used in anti-acne creams. Tinctures are alcohol-based extracts from plants. The researchers grew the bacterium that causes acne – Propionibacterium acnes – in the laboratory for four days. They then added the tinctures, benzoyl peroxide or an alcohol solution to different samples of the bacteria. The alcohol was used to provide a control substance to compare the tinctures with, which would help to determine whether any effects produced by the tinctures were due to the plant-derived substances they contained or the alcohol used to make them. After five minutes the researchers looked at how much of the bacteria had been killed.
What were the basic results?
The researchers found that marigold, myrrh and thyme tinctures had a greater antibacterial effect than the control alcohol solution. The thyme tincture had the greatest effect, with a specific concentration of tincture reducing bacteria levels more than benzoyl peroxide did, with the latter at the highest concentration prescribed to patients.
How did the researchers interpret the results?
The researchers concluded that their study showed a strong antimicrobial effect against acne-causing bacteria in the lab, and that this suggests it may be useful as a treatment of acne.
From the brief details available, this laboratory study has shown that thyme extract can kill the bacteria that cause acne in the laboratory. However, as this research has only been presented as a conference abstract so far, the lack of detail means we can’t tell much about its full methods and results. Given this lack of detail, as well as the fact that this was research on bacteria in a lab and not in humans, the results and their implications should be viewed with some caution.
The press release for the research says that “a herbal treatment for acne would be very welcome news” as “herbal preparations are less harsh on the skin due to their anti-inflammatory properties”. However, this study has not looked at the effect of the tincture on human skin, so it is not possible to say yet whether it would be any more effective than existing acne creams, or be more tolerable for human skin at the concentration that kills bacteria. Furthermore, some herbs are known to cause skin rashes, so any potential harms from this tincture need to be fully investigated before use.
There is already a range of treatments available for people with acne, and some of these can be prescribed by your doctor in severe cases. Find out more about acne from NHS Choices.
Analysis by Bazian