Cloves for toothache

Using cloves as an anesthetic

My husband had toothache a few weeks ago, and while he awaited his appointment at the dentist, he resorted to local application of an occasional drop of the well-known anesthetic, clove oil. At the same time, I had a sore throat and asked if it could help that too. He looked it up on the internet and told me I could gargle with two drops of the oil in a cup of warm water. This gave me a pleasant fresh taste in my mouth and a mild, short-lived numbing effect. Do be aware, though, that clove oil should only be used diluted and in small quantities.
cloves natural toothache remedy

Cloves contain Eugenol

Eugenol is the active ingredient in clove oil, and can also be found in spices such as nutmeg and cinnamon as well as the herbs basil and bay. It acts as an analgesic by blocking nerve conduction and has various other properties including as an antibacterial [1].

clove plant boston library

This picture of a clove plant was sourced from Boston Public Library on Flikr – a great resource for free vintage images.

The botanical name of the clove plant is Syzygium aromaticum. The plant is an evergreen which is native to Indonesia, and it is the dried flower bud which is used as a spice, although the stem and leaf also contain significant quantities of the active compound eugenol.
whole cloves spice analgesic

Antibacterial properties of cloves

The antibiotic nature of cloves can be attributed to the presence of eugenol, although other phytochemicals are of course present in the spice. It is possible that the relatively long shelf-life of spiced food may be an indicator of this germ-killing effect. Eugenol has been found to work by disrupting bacterial cell membranes [2]. There has been decades of work on the possibility of using various herbs and spices including cloves for use as antibiotics [3]. Work has been carried out to evaluate essential oils from spices for targeting resistant antibiotics for some time and there is some evidence to show that combining particular herbs and spices may have a particularly good effect [4].

natural antibiotic clove

Possible Future Uses of Spices as Antibiotics

There is currently an international race to beat antibiotic resistance. Going back to nature is one route that scientists are pursuing to find new ways of beating bacteria. Additionally, poorer countries may prefer to find natural, non-patented medicines which are likely to be cheaper than manufactured ones. However, because cloves can be an irritant, causing sensitization with repeated exposure, and are poisonous in larger doses, their usefulness may be limited.

Clove Oil Cautions

As mentioned above, clove oil should be used diluted and sparingly. As with many essential oils and medicines, it is poisonous in large quantities, and repeated use can result in sensitization. If you have dental discomfort, see your dentist as soon as possible. Do not use if pregnant.

Scientific References for the use of Eugenol and Clove Oil

[1] Advances in Pharmacological Research of Eugenol, Xiaojun KONG, Xiwang LIU, Jianyong LI, Yajun YANG, Curr Opin Complement Alternat Med 1:1, 8-11; January/February 2014
[2] The proposed mechanism of bactericidal action of eugenol, -terpineol and -terpinene against Listeria monocytogenes, Streptococcus pyogenes, Proteus vulgaris and Escherichia coli, S. O. Oyedemi*, A. I. Okoh, L. V. Mabinya, G. Pirochenva and A. J. Afolayan, African Journal of Biotechnology Vol. 8 (7), pp. 1280-1286, 6 April, 2009
[3] Bioactive Volatile Compounds from Plants, Editors: Roy Teranishi, Ron G. Buttery, Hiroshi Sugisawa, American Chemical Society Symposium series, Volume 525, April 06 1993
[4] Antibacterial Activity of Plant Extracts and Phytochemicals on Antibiotic-resistant Bacteria, Gislene G. F. Nascimento; Juliana Locatelli; Paulo C. Freitas; Giuliana L. Silva, Braz. J. Microbiol. vol.31 no.4 São Paulo Oct./Dec. 2000

Stevia and the No Added Sugar controversy

Can the herb stevia provide the answer to chemical additives?

Artificial sweeteners and the proposed sugar tax

As I write this, there is a national campaign fronted by Jamie Oliver to tax sugary drinks. This is an admirable battle in the war against childhood obesity, with primary schools and the NHS standing to share £1bn in revenue if the scheme should ever go ahead. However, this is a complex issue and it is possible that artificial sweeteners such as saccharin, aspartame and sucralose may also be damaging to health. The leaves of a herb called stevia might provide the answer.

The limitations of artificial sweeteners

A small study was recently carried out on BBCs Trust Me I’m a Doctor, in which 15 volunteers switched to either saccharin or stevia and had their blood sugar levels and gut bacteria tested before and after. Fasting blood sugar levels were found to be significantly higher for certain people in the group taking saccharin than they were previously. The results of the gut bacteria tests showed that those people who had high blood sugar after taking saccharin all had a similar bacterial composition, whereas stevia consumption seemed to have no effect on blood sugar across all gut bacteria types. This study was itself inspired by a research paper published in the science journal Nature [1]. The article found a link in mice between NAS (non-caloric artificial sweeteners) and glucose intolerance which the team attributed to altered composition of gut bacteria. The BBC team says:

“Although our study, and the one that preceded it, were both on small numbers of people, the consistent results – alongside the results found previously in mice – certainly suggest that saccharin is bad for some people, whilst we have no evidence that stevia is. The people whom saccharin tends to affect seem to be those with a specific gut bacteria composition.”

As most people won’t know their gut bacteria composition, the team’s advice was to avoid saccharin. The team also pointed out that evidence in mice is that aspartame and sucralose may have a similar effect.

There is no other research like this for the effect of stevia at the moment, but in the meantime, the Trust Me team says:

“…if you are looking for a sugar alternative then at the moment, stevia seems most likely to be the best out there. On the back of packaging it is sometimes called ‘steviol glycosides’, which are the sweet-tasting compounds in the Stevia plant.”

It should be noted that both of these studies were small scale, so any findings would have to be explored further before arriving at a full understanding of the effects of artificial sweeteners.

More about the herb stevia

Stevia rebaudiana is a natural herb which can be used as a sweetener and may not work in the same way as artificial additives, so may not have the same drawbacks. It is native to South America and enjoys the humidity there, but can be grown in the UK if treated as a tender perennial. Unsurprisingly one of its common names is sweetleaf!

herb plant stevia

The herb stevia can be grown in the UK as a tender perennial.

Medical Herbalist Barbara Wilkinson says*:

Stevia is a herb I grow for general use as an alternative to sugar with all it’s negative effects. It  has been grown and used for centuries in South America and Japan but has been ignored in the UK until recently. It can be grown here if protected from cold and frost, so treat like someone you love. There is a taste like liquorice if used in excess as the bitter chemicals it contains play with our taste buds. It is non-calorific and doesn’t mess with our blood glucose levels. No wonder Coca cola are now using it as people wake up to the dangers of sugar. Consumers should be aware that manufactured brands of stevia sweetener may contain other ingredients such as erythritol, so grow your own or buy from an organic reputable source.
drying stevia leaves

Use a herb dryer to preserve stevia leaves for use year-round

Risks and benefits of stevia and other sweeteners

In reviewing the literature relating to this topic, it becomes clear that there is still much research to do in this field. Links have been found between artificial sweeteners and obesity, for example Dr Tandel writing a review in 2011 says [2]:

“There is some ongoing controversy over whether artificial sweetener usage poses health risks. A study done in 2005 by the University of Texas Health Science Center at San Antonio showed that, rather than promoting weight loss, the use of diet drinks was a marker for increasing weight gain and obesity. Those who consumed diet soda were more likely to gain weight than those who consumed naturally-sweetened soda. Animal studies have convincingly proven that artificial sweeteners cause body weight gain.

It would be a shame if we all switched to artificial sweeteners only to find that we had made things worse. Most supermarket fizzy drinks already contain NAS as a matter of routine. It does seem sensible to try and reduce our intake of sweet things overall, rather than just switching from sugar to sweetener.

As for stevia, the initial signs look promising for the use of this herb as it seems to work differently, but its effects are less well known than those of saccharin.

To summarise, for a healthy diet, it would seem sensible to reduce sugar intake and avoid artificial sweeteners wherever possible. If you are looking to replace artificial sweeteners, try pure stevia in moderation but be aware that commercial processed brands may contain other ingredients.

We are looking forward to reading further research on this subject!

[1] J. Suez et al, Artificial sweeteners induce glucose intolerance by altering the gut microbiota, Nature 514, 181–186 (09 October 2014)

[2] K. R. Tandel, Sugar substitutes: Health controversy over perceived benefits, J. Pharmacol, 2011, 2, 4, 236

*writing in the Herb Society e-newsletter January 2015. The email newsletter is one of many benefits of becoming a Herb Society member. Find out more in our Herb Society membership leaflet.

Image credits Barbara Wilkinson who is a Herb Society trustee.

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Scientific evaluation of lavender

Medical use of the popular herb

Following on from the previous article about the cognitive effects of sage and rosemary, it might be interesting to look at scientific evidence for the effects of lavender, as this is arguably Britain’s most popular and useful flowering herb.

scientific testing lavender herb

Lavender has a range of claimed effects, and here we discuss some of these one by one:

  • Lavender is anti-bacterial
  • Lavender is anti-fungal
  • Lavender is anti-parasitic
  • Lavender is relaxing

Other claims that we don’t have time to discuss here are its carminative (smooth muscle relaxing) effects; effectiveness for burns and insect bites; as an anti-viral and insect repellent.

Problems in assessing lavender

Most research into the effects of lavender have been carried out using lavender essential oil, which contains a mixture of many chemicals such as linalool and linalyl acetate. However, the chemical make-up of the oil can vary greatly. Not only might different species of the herb (for example Lavandula angustifolia compared with Lavandula x intermedia) contain different combinations of chemicals, but also the growing conditions may affect which chemicals predominate. The extraction method could also conceivably influence the balance of oil components. To summarise the overall view, Cavanagh and Wilkinson from Charles Sturt University Australia in their scientific review of the biological activity of lavender essential oil wrote,

“Although the data are still inconclusive and often controversial, there does seem to be both scientific and clinical data that support the traditional uses of lavender. However, methodological and oil identification problems have severely hampered the evaluation of the therapeutic significance of much of the research on Lavandula spp. These issues need to be resolved before we have a true picture of the biological activities of lavender essential oil.”[1]

Since writing those words in 2002, Cavanagh and Wilkinson have gone a long way towards elucidating the role of lavender in medicine.

properties lavender herb

Is lavender antifungal?

Yes, Cavanagh, Wilkinson and co-workers found that lavender essential oils could be used against various fungi. For example Lavandula angustifolia and Lavandula x intermedia were effective against Trichophyton mentagrophytes (a fungus associated with skin conditions such as ringworm) and others including Aspergillus nidulans (a fungus commonly used in research). [2]

Lavender essential oil is clearly active against the fungi tested in vitro, but it might be naive to assume a blanket effect for all, and clinical trials have not been carried out.

Is lavender antiparasitic?

Yes again! In their paper on the subject in 2006, the same research team found that Lavandula angustifolia and Lavandula x intermedia essential oils can completely eliminate Trichomonas vaginalis (the most common pathogenic protozoan infection of humans in industrialized countries) and Giardia duodenalis (an intestinal parasite) in vitro when the oil is used at a concentration of 1%. [3]

It should be noted that these trials were again carried out in vitro, and so although the parasites were killed by lavender oil on a petri dish, the suitability of taking lavender orally for this purpose is another question entirely.

Is lavender antibacterial?

Yes – the team in Australia evaluated various lavender essential oils against bacteria including Streptococcus pyogenes, Staphylococcus aureus, MRSA, Citrobacter freundii, Proteus vulgaris, Escherichia coli, VRE and Propionibacterium acnes. Pseudomonas aeruginosa was the only bacterium in the experiment not found to be susceptible to any lavender essential oil tested. The team tested varieties of Lavandula angustifolia and Lavandula x intermedia as well as other less well known species.

As with the findings for use of lavender as an antifungal, results imply that topical application of lavender oil (for example on an infected wound) is most likely to be the way forward.[4][5] This is not breaking news – lavender was used during the First World War to treat soldiers in the military hospitals.

Relaxing properties of lavender

The relaxing nature of lavender has been well documented, including a trial reported in 2005 in which dental patients were exposed to the fragrance before receiving treatment[6]. Various trials have since been carried out, as discussed in this popular article on the BBC website about lavender.

Allied to lavender’s relaxing properties, clinical trials are currently under way which investigate the role of lavender in treating dementia and Alzheimers. Professor Elaine Perry reports in one such paper [7]:

“all treatments resulted in significant benefit, including (in most instances) reductions in agitation, sleeplessness, wandering and unsociable behaviour.”

Lavender – A good all-rounder

So if lavender is so useful, why does it not appear more often in mainstream medicine? There are various answers to this:

  • Lavender oil contains a chemical called linalool which may be associated with skin sensitisation[8].
  • Lack of clinical testing. This may be partially due to lack of funding. Much drug development is carried out by pharmaceutical companies wishing to patent a novel chemical which they can make a profit on. So developments in the use of lavender are only likely to happen in Government funded research in universities and hospitals.
  • There is a difference between an oil being active on the skin (for example as an antibiotic) and it being active internally. If swallowed, active ingredients may be broken down in the gut; they may fail to travel to where they are needed, or side effects may occur. Luckily with effects on the brain, such as relaxation, inhalation seems to be a feasible delivery method (see previous blog post which touched on the scientific basis for aromatherapy).

Although lavender oil obviously has many benefits, the Herb Society recommends that anyone experiencing medical symptoms or feeling ill should contact their doctor in the first instance. Consult a medical herbalist for guidance regarding medicating with lavender.

[5] Cavanagh, H. M. A. and Wilkinson, J. M. (2005),Lavender essential oil: A review, Healthcare Infection 01/2005; 10(1). DOI: 10.1071/HI05035

[7] Prof. Elaine Perry, Aromatherapy for the treatment of Alzheimer’s disease,  J. Quality Res Dementia, Issue 3

[8] Prashar, A., Locke, I. C. and Evans, C. S. (2004), Cytotoxicity of lavender oil and its major components to human skin cells. Cell Proliferation, 37: 221–229. doi: 10.1111/j.1365-2184.2004.00307.x

Cognitive effects of herbs rosemary and sage

Rosemary for Remembrance

There was a lot of interest recently in a programme on the BBC in which rosemary essential oil vapour in a room was shown to improve the memory of test subjects, and that the active ingredients were able to be detected in the subjects’ bloodstreams afterwards. You can read more about this experiment in an article on the BBC website written by Dr Chris Van Tulleken, which was based on scientific research undertaken by Jemma McCready and Dr Mark Moss in the Psychology Department at Northumbria University [1]. They found that

“…performance levels and changes in mood following exposure to the rosemary aroma were related to concentrations of a compound (1,8-cineole) present in the blood. The compound is also found in the essential oil of rosemary and has previously been shown to act on the biochemical systems that underpin memory.

The results showed that participants in the rosemary-scented room performed better on the prospective memory* tasks than the participants in the room with no scent. This was the case for remembering events and remembering to complete tasks at particular times.”

[*Prospective memory means remembering to do something in the future, such as “I must remember to buy some milk”.]

This research not only has an impact for herbalists, but also supports a scientific basis for aromatherapy – see the next heading below.

rosemary herb flowers

Other research on rosemary around the World includes effects of the use of rosemary in food. Studies sponsored by the McCormick Science Institute found that culinary levels of dried rosemary leaf powder were found to have beneficial effects on cognitive skills when testing a small sample of older patients [2].

Scientific basis for aromatherapy

Clearly the research discussed on the TV programme above shows that fragrance can not only affect your mood, but also your cognitive ability. It supports the growing evidence that fragrance chemicals in the air, even in small concentrations, are detectable in the blood stream and can have a measurable effect, with results having been reported for essential oils such as lavender as long as twenty years ago [3]. It has been suggested that inhaled molecules have an increased opportunity to enter the brain by bypassing the blood-brain barrier, which normally restricts movement of chemicals into this organ [4]. A review on the scientific basis for aromatherapy was recently published in the Asian Pacific Journal of Tropical Biomedicine [5] and contains many useful references.

Cognitive effects of sage

The effect of herbs on the brain seems to be a topic of interest for the BBC, because a year ago they published a similar article by TV Doctor Michael Mosely regarding the herb sage in which he quotes a scientific review paper assessing pharmacological properties of Salvia on memory [6] which he summarised as “extracts of sage can enhance cognitive performance and it is safe”.

The paper states that sage taken orally looks promising for the management of mild to moderate Alzheimer’s disease, but more detailed standardised clinical trials are needed.

So it appears the common name of this plant actually has a sound basis in science. The dictionary definition of sage is “wise and judicious”, but a brief search revealed no reference to a historic link between the two. If you know of a link, do get in touch!

Herbs Rosemary and Sage may inhibit the breakdown of neurotransmitters

rosemary memory herb

It is suggested that rosemary and sage may have an effect because they contain cholinesterase inhibitors. Acetylcholine is a naturally occurring chemical in the brain, which acts as a neurotransmitter (a substance which transfers an impulse between nerve cells). Cholinesterase is an enzyme in the brain which breaks down acetylcholine, and the herbs discussed may contain a chemical which prevents this happening. Some people with memory problems have been found to have low levels of acetylcholine in the brain.

However, more research is needed into this pathway, and Dr Mark Moss and team point out that any cognitive effect is likely to be a complex one.

[1] Plasma 1,8-cineole correlates with cognitive performance following exposure to rosemary essential oil aroma, Ther Adv Psychopharmacol. 2012 Jun; 2(3): 103–113

[2] Short-term study on the effects of rosemary on cognitive function in an elderly population, J. Med. Food, 14(0), 2011, 1-

[3] Fragrance compounds and essential oils with sedative effects upon inhalation,  J. Pharm. Sci. Vol. 82, Issue 6, 1993, Pages 660-664

[4] Bypassing the Blood-Brain Barrier to Deliver Therapeutic Agents to the Brain and Spinal Cord, Drug Development & Delivery Vol. 2 No. 5 July/August 2002

[5] Essential oils used in aromatherapy: A systemic review, Asian Pacific Journal of Tropical Biomedicine, Volume 5, Issue 8, August 2015, Pages 601–611

[6] Systematic review of clinical trials assessing pharmacological properties of Salvia species on memory, cognitive impairment and Alzheimer’s disease, CNS Neurosci Ther. 2014 Jun;20(6):485-95