Kānuka & inflammation

Posted: December 2022

Author: Phil Rasmussen | M.Pharm., M.P.S., Dip. Herb. Med.; M.N.I.M.H.(UK), F.N.Z.A.M.H.
 

Inflammation is a component of most, if not all illnesses, and can be both acute or chronic. But it’s also important to acknowledge that inflammation is, of course, a normal and healthy response to an attack or injury to a part of our body. It signals and underlines an attempt to manage something that is threatening our health or survival. We have a multitude of different phytomedicines which can support the body during periods of inflammatory stress. One such herb is the New Zealand native kānuka.

The main species of kānuka (Kunzea ericoides) is endemic. Together with its allies, it is part of a distinct eastern Australia-New Zealand subgenus now named Niviferae, meaning snow-covered. This is because of the tendency to cover themselves in masses of white flowers.

Kānuka and mānuka are closely related plants botanically. To the untrained eye, it is certainly difficult to distinguish between them at times. To elderly Māori, the name mānuka was the generic name usually applied to Kunzea spp, not kānuka. Similarly, the name kahikatoa was used for Leptospermum. It is therefore no surprise that they were sometimes used interchangeably by Māori using traditional rongoā medicine, for many inflammatory conditions. These traditional uses include topically for inflammatory conditions such as sprains, strains and swellings, as well as burns, broken limbs and rheumatism.^1-3

Like all tannin-rich and antimicrobial plants, local applications made from the leaves or bark were applied for inflammatory and damaged skin conditions. These include minor wounds, cuts and grazes. Inflamed tissue such as mucous membranes of the mouth, gums and vagina, also seem to respond well to topical treatment with kānuka preparations, especially where these are associated with bleeding.

Kānuka also has useful actions on inflammation affecting the digestive tract, including that associated with diarrhoea and dysentery. Its combination of astringent, antimicrobial and pronounced anti-inflammatory properties make it useful for conditions such as irritable bowel or where looseness is a feature.

The essential oil of kānuka has become increasingly of interest and the subject of research in recent years. Its phytochemical makeup is complex and diverse, and of course, varies considerably depending on the location and variety of the plants from which it is sourced. While β-triketone compounds are generally but not always lacking, the oil usually contains a large number of sesquiterpene compounds and especially α-pinene.

Anti-inflammatory and spasmolytic activities have been reported for kānuka oil in various studies.^{4, 5} A number of clinical trials using topical products made from kānuka oil have also been undertaken over the past few years, most with favourable findings.

Australian researchers reported clinical improvement following the application of an ointment containing Kunzea oil to horses with pastern dermatitis, an inflammatory condition of their hooves, in 2009.6 A 14-week single-blind clinical trial recently reported that twice daily application of a serum containing 3% kānuka oil for six weeks, led to a significant improvement in patients with moderate to severe eczema.⁷

The anti-inflammatory, as well as antimicrobial (antibacterial, antifungal and antiviral) actions of kānuka oil, also contribute to its use in some infectious conditions. This is given that inflammation is often the key contributor to symptoms of conditions such as athlete’s foot or Tinea. It has an ideal combination of antimicrobial and anti-inflammatory properties, for this application.⁵

As with honey from its mānuka cousin, kānuka honey has also steadily gained a reputation for the management of some inflammatory skin conditions. Kānuka honey-based products have been shown to reduce the inflammation and symptomatology of rosacea⁸, as well as acne.⁹ Another trial found a kānuka honey product to be as effective as topical acyclovir for the treatment of herpes simplex labialis (genital herpes) in women.¹⁰

Together with mānuka, kānuka is also regarded as a ‘first wave’ or colonisation plant that cleanses and prepares the soil for a future healthy forest. This important role in nature is evident from research showing it reduces E. coli levels in dairy effluent-contaminated soils and the resulting nitrous oxide emissions.¹¹ As well as inhibiting the infectious spores of the microbe that causes kauri dieback disease.¹²

Undoubtedly more findings will continue to emerge on how we can use this common plant of Aotearoa New Zealand, in other clinical situations where inflammation is a key component.

References:

1. Brooker SG, Cambie RC, Cooper RC. New Zealand Medicinal Plants. Heinemann Publishers, Auckland, 1981.
2. Riley M., “Maori Healing and Herbal: New Zealand Ethnobotanical Sourcebook”, Viking Sevenseas, Paraparaumu, N.Z., 1994.
3. Rasmussen PL, New Zealand Native plants. Part 1. Phytomed Webinar, September 2018.
4. Lis-Balchin M, Hart SL. An investigation of the actions of the essential oils of Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides), Myrtaceae on guinea-pig smooth muscle. J Pharm Pharmacol. 1998;50(7):809-811.
5. Chen CC, Yan SH, Yen MY, et al. Investigations of kanuka and manuka essential oils for in vitro treatment of disease and cellular inflammation caused by infectious microorganisms. J Microbiol Immunol Infect. 2016;49(1):104-111.
6. Thomas J, Narkowicz C, Peterson GM, Jacobson GA, Narayana A. Randomised controlled trial of the treatment of pastern dermatitis with a formulation containing kunzea oil. Vet Rec. 2009;164(20):619-623.
7. Shortt N, Martin A, Kerse K, et al. Efficacy of a 3% Kānuka oil cream for the treatment of moderate-to-severe eczema: A single blind randomised vehicle-controlled trial. EClinicalMedicine. 2022;51:101561.
8. Braithwaite I, Hunt A, Riley J, et al. Randomised controlled trial of topical kanuka honey for the treatment of rosacea. BMJ Open. 2015;5(6):e007651.
9. Semprini A, Braithwaite I, Corin A, et al. Randomised controlled trial of topical kanuka honey for the treatment of acne. BMJ Open. 2016;6(2):e009448.
10. Semprini A, Singer J, Braithwaite I, et al. Kanuka honey versus aciclovir for the topical treatment of herpes simplex labialis: a randomised controlled trial. BMJ Open. 2019;9(5):e026201.
11. Fitzgerald Roshean, Potential of manuka and kanuka for the mitigation of nitrous oxide emissions from NZ dairy farms. Dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science with Honours, Lincoln University, New Zealand, 2012.
12. Lawrence SC, Burgess EJ, Pairama Cl, Black A, Patrick WM, Mitchell I et al, Mātauranga-guided screening of New Zealand native plants reveals flavonoids from kānuka (Kunzea robusta) with anti-Phytophthora activity. J Royal Society of New Zealand, 2019; 49:S1, 137-154.