Mānuka

Leptospermum scoparium

Common & Folk Names

• Tea Tree (New Zealand)
• New Zealand Tea Tree
• Kahikātoa (Māori)
• Mānuka (Māori)
• Red Manuka
• Manuka Myrtle
• Jelly Bush
• Broom Tea-Tree

Plant Family

Myrtaceae (Myrtle family)

Geographic Location

Mānuka is native to New Zealand and southeastern Australia (including Tasmania). It grows throughout both the North and South Islands of New Zealand, from coastal areas to subalpine regions. It is now cultivated in other regions with similar climates for honey production and ornamental purposes, though the highest-quality therapeutic honey comes from specific regions, particularly the East Cape area of New Zealand’s North Island.

Habitat

Mānuka thrives in open, sunny locations, often colonising disturbed land, scrublands, forest margins, and coastal areas. It prefers well-drained, acidic to neutral soils and can tolerate poor, sandy, or clay soils, as well as windy and exposed conditions. As a pioneer species, it plays a crucial ecological role in stabilising soils and regenerating native bush in New Zealand.

Growing Conditions

Sun: Requires full sun for optimal growth and flower production

Soil: Adaptable but prefers light, well-drained, slightly acidic soils (pH 5.0-6.5). Tolerates a wide pH range and poor fertility

Propagation: Easily grown from seed (requires light for germination) or semi-hardwood cuttings taken in late summer. Seeds germinate best with light exposure. Cuttings root well with hormone treatment

Care: Drought-tolerant once established. Benefits from light pruning after flowering to maintain shape and encourage bushiness. Can become invasive in some non-native habitats. Young plants may need protection from frost

NZ Planting Calendar

Sowing (seeds): Spring (September–November) – requires light for germination

Propagation (cuttings): Late summer (February–March) – semi-hardwood cuttings with hormone treatment

Planting: Spring (August–October) for best establishment

Flowering: November–February (spring/summer) – masses of white to pink flowers

Harvest (leaves/stems): Just before or during early flowering (November–December) when volatile oil content is highest; year-round harvest possible

Note: Native to NZ and southeastern Australia; pioneer species; East Cape region produces triketone-rich chemotype; becomes invasive in some areas

Harvesting Guidelines

For medicinal use, the leaves and small stems are typically harvested just before or during early flowering when volatile oil content is highest. Harvest on a dry, sunny morning after dew has evaporated. Flowers for decorative or honey production are harvested when fully open. Sustainable wildcrafting practices are strongly encouraged due to mānuka’s ecological importance and the pressure from commercial honey production. When harvesting from the wild, take only small amounts from multiple plants and ensure regeneration.

Parts Used

• Leaves
• Small stems (twigs)
• Essential oil (distilled from leaves and stems)
• Honey (produced from nectar by Apis mellifera)

Constituents & their Actions

Mānuka contains a range of bioactive compounds that contribute to its strong antimicrobial and healing reputation. The plant’s chemistry varies significantly by chemotype and geographic location, with the East Cape region of New Zealand producing the triketone-rich chemotype most valued for therapeutic use.

β-Triketones:

These unique cyclic compounds are the signature constituents of mānuka essential oil from the East Cape chemotype and are responsible for its potent antimicrobial activity. These compounds are relatively rare in nature, found primarily in Myrtaceae species. Some of the main β-triketones in mānuka are:

• Leptospermone (the predominant triketone)
• Isoleptospermone
• Flavesone
• Grandiflorone

The main actions of these β-triketones are:

• Broad-spectrum antimicrobial (antibacterial, antifungal, antiviral)
• Cell membrane disruption in pathogens
• Anti-inflammatory through enzyme inhibition
• Potential antiparasitic activity

Essential Oils (Volatile Oils):

Beyond the triketones, mānuka oil contains a complex mixture of aromatic compounds. The composition varies by chemotype, with some plants containing high monoterpene content and others being sesquiterpene-rich. Some key volatile constituents are:

• Sesquiterpene hydrocarbons (60-70% in triketone chemotype): including cadinene, copaene, elemene, aromadendrene, and calamenene groups
• Monoterpenes (variable, 3-50% depending on chemotype): including α-pinene and β-pinene
• Oxygenated sesquiterpenes: including viridiflorol

The main actions of these volatile oils are:

• Antimicrobial support (synergistic with triketones)
• Anti-inflammatory
• Aromatic and expectorant properties

Triterpenoids:

These compounds contribute to anti-inflammatory and wound-healing actions. One of the main triterpenoids in mānuka is:

• Ursolic acid

The main actions of these triterpenoids are:

• Anti-inflammatory (COX enzyme inhibition)
• Wound healing promotion (vulnerary)
• Antioxidant support

Flavonoids:

These polyphenolic compounds provide antioxidant protection and support anti-inflammatory and antimicrobial effects. Some of the main flavonoids in mānuka are:

• Quercetin
• Myricetin
• Catechin

The main actions of these flavonoids are:

• Powerful antioxidant activity
• Anti-inflammatory (multiple pathways)
• Antimicrobial support
• Vascular support

Tannins:

These polyphenolic compounds have a toning and tightening effect on tissues.

The main action of tannins is:

• Astringent action (tissue toning and tightening)

Honey-Specific Constituents:

Mānuka honey contains unique compounds not found in other honeys:

• Methylglyoxal (MGO): Formed from dihydroxyacetone (DHA) present in mānuka nectar; responsible for non-peroxide antibacterial activity
• Dihydroxyacetone (DHA): Precursor to MGO, present in high concentrations in mānuka nectar
• Leptosperin: A marker compound unique to Leptospermum honeys, used for authentication

Actions with Mechanisms

Antimicrobial (Broad-Spectrum):
The β-triketones in mānuka essential oil disrupt bacterial and fungal cell membranes through their hydrophobic properties, which in turn causes leakage of cellular contents, disruption of ion gradients, and inhibition of cellular respiration, leading to microbial death. The methylglyoxal (MGO) in mānuka honey achieves antimicrobial effects through protein glycation and modification of bacterial cell structures, which in turn disrupts metabolic functions and prevents biofilm formation. This dual-action antimicrobial activity is effective against both Gram-positive and Gram-negative bacteria, including antibiotic-resistant strains such as MRSA, as well as fungi and certain viruses.

Anti-inflammatory:
The flavonoids (particularly quercetin) and triterpenoids (ursolic acid) in mānuka inhibit pro-inflammatory enzymes including cyclooxygenase (COX) and lipoxygenase (LOX), which in turn reduces the production of inflammatory mediators such as prostaglandins and leukotrienes. Additionally, mānuka honey modulates immune cell activity by influencing cytokine production (TNF-α, IL-1, IL-6), which in turn helps resolve inflammation while maintaining appropriate immune response. The reduction in inflammatory macrophage activity and faster transition to tissue remodelling phases contributes to this action.

Wound Healing (Vulnerary):
Triterpenoids and the astringent action of tannins promote tissue contraction and stimulate fibroblast proliferation, which in turn accelerates collagen synthesis and new tissue formation. The honey creates a moist wound environment and provides osmotic action that draws fluid from the wound bed, which in turn cleanses the wound and reduces edema. Mānuka honey stimulates angiogenesis (new blood vessel formation), which in turn ensures adequate oxygen and nutrient delivery to healing tissues. The acidic pH of honey (3.2-4.5) creates an environment conducive to healing, which in turn supports epithelialisation and reduces infection risk. Clinical evidence shows significantly faster reepithelialisation and improved epidermal regeneration compared to conventional dressings.

Antioxidant:
Flavonoids such as quercetin and myricetin donate electrons to neutralise free radicals through direct scavenging mechanisms, which in turn prevents oxidative damage to cellular lipids, proteins, and DNA. The phenolic compounds in mānuka honey also contribute to antioxidant capacity through multiple mechanisms, which in turn supports tissue repair and reduces inflammation-associated oxidative stress. This antioxidant activity is particularly beneficial during wound healing when oxidative stress is elevated.

Expectorant:
When used as a steam inhalation or taken internally, the volatile oils stimulate respiratory mucosal secretion and help mobilise congestion, which in turn makes coughing more productive and supports clearance of respiratory irritants. The antimicrobial properties simultaneously address respiratory infections, which in turn reduces the bacterial or viral load contributing to congestion.

Digestive Support:
The anti-inflammatory and mild astringent actions of the tannins and flavonoids help soothe an irritated digestive tract lining, which in turn may reduce discomfort associated with minor gastric inflammation. Animal studies suggest mānuka honey can reduce gastric ulcer formation and support mucosal lining repair through multiple mechanisms, which in turn protects against acid damage and promotes healing of existing erosions.

Immune Modulation:
Mānuka honey activates phagocytosis and stimulates proliferation of B and T lymphocytes, which in turn enhances the body’s ability to respond to pathogens. The honey also contributes to activation of monocytes through release of important cytokines (TNF, IL-1, IL-6), which in turn supports local immune response at wound sites and systemically when consumed internally.

Tissue Remodeling Support:
The reduction in Ki67 expression (a marker of cell proliferation) observed in later healing stages suggests mānuka honey helps transition wounds from inflammatory phase to organised tissue remodelling, which in turn reduces excessive scarring and promotes more organised collagen deposition. The stimulation of keratinocyte activity supports proper epithelial layer formation, which in turn results in better cosmetic outcomes and restored barrier function.

Main Use

Mānuka’s primary use is as a topical antimicrobial and wound-healing agent, where it has gained international recognition for its exceptional therapeutic properties. Medical-grade mānuka honey is particularly renowned for addressing skin infections, minor cuts and abrasions, burns (including partial-thickness burns), chronic wounds (venous leg ulcers, pressure ulcers), acne, and fungal conditions like athlete’s foot. The honey is graded for its non-peroxide antibacterial activity using either the Unique Manuka Factor (UMF) rating or methylglyoxal (MGO) content measurement, with therapeutic-grade honey requiring a minimum UMF of 10+ (corresponding to MGO >260 mg/kg).

The essential oil from mānuka leaves provides complementary topical antimicrobial support, particularly for skin infections, wound care, and fungal conditions. When properly diluted, the oil can be used in creams, ointments, or diluted applications for its powerful antibacterial and antifungal properties.

Internally, the leaf tea has a traditional history of use for soothing respiratory congestion, urinary tract discomfort, and mild digestive upset. Mānuka honey taken internally supports immune function, provides relief for sore throats and upper respiratory infections, and may offer gastroprotective benefits for minor digestive inflammation.

Preparations

Tea/Infusion: 1-2 teaspoons of dried leaves per cup of boiling water. Steep covered for 5-10 minutes. Drink up to three times daily for respiratory support, digestive comfort, or immune support

Tincture: (1:5 in 40-50% alcohol). Take 2-4 mL, 2-3 times daily for immune and digestive support

Essential Oil (Topical): Use only high-quality, triketone-rich therapeutic-grade oil. Dilute to 2-5% in carrier oil for topical antimicrobial applications. 1-2 drops in 5 mL (1 teaspoon) carrier oil. Apply to affected skin areas. For fungal infections, may use up to 10% dilution under professional guidance

Steam Inhalation: Add 2-3 drops essential oil or handful of fresh leaves to bowl of hot water. Inhale steam for 5-10 minutes for respiratory congestion

Medical-Grade Honey (Topical): Apply UMF 10+ or higher honey directly to clean wounds, burns, or skin infections. Cover with appropriate dressing. Change daily or as directed by healthcare provider. Thickness of application varies by wound type (typically 3-5mm layer)

Medical-Grade Honey (Internal): Take 1-2 teaspoons (5-10 mL) of UMF 10+ or higher honey 1-3 times daily for immune support, sore throat, or digestive support. Can be taken directly or dissolved in warm (not hot) water or herbal tea

Honey Wound Dressing: For serious wounds, use sterile medical-grade mānuka honey dressings available from medical suppliers. Follow healthcare provider guidance for application and changing frequency

Dosage

Dried Herb (Tea): 1-2 teaspoons (2-4 grams) per cup, steeped 5-10 minutes, 2-3 times daily

Tincture (1:5, 40-50% alcohol): 2-4 mL (40-80 drops), 2-3 times daily

Essential Oil (Topical): 2-5% dilution in carrier oil (1-2 drops per teaspoon of carrier). Apply to affected areas 2-3 times daily

Medical-Grade Honey (Topical): Apply sufficient honey to cover wound (typically 3-5mm layer). Change dressing daily or as needed

Medical-Grade Honey (Internal): 1-2 teaspoons (5-10 mL) of UMF 10+ or higher, 1-3 times daily

Safety & Drug Interactions

Scientific Evidence

Wound Healing: Multiple clinical trials and in vivo studies provide robust evidence for mānuka honey’s wound-healing properties. Recent studies in porcine models (which closely mimic human skin) demonstrate significantly increased collagen density, faster reepithelialisation, and improved epidermal regeneration compared to conventional antibiotic ointments. A 2025 clinical trial of 80 patients with chronic venous leg ulcers found that mānuka honey achieved complete healing within 7 weeks in all patients, compared to 14 weeks in the control group using antimicrobial calcium alginate dressings. Studies on burns have consistently shown faster healing times with mānuka honey compared to standard treatments, including silver sulfadiazine. The evidence supports use for partial-thickness burns, chronic leg ulcers, pressure ulcers, and post-surgical wounds.

Antimicrobial Activity: Extensive laboratory research confirms mānuka’s broad-spectrum antimicrobial activity against diverse bacterial and fungal pathogens, including antibiotic-resistant strains such as MRSA. The antimicrobial activity correlates strongly with methylglyoxal (MGO) content, with therapeutic activity requiring MGO concentrations above 260 mg/kg (corresponding to UMF 10+). Studies demonstrate that MGO concentrations of 1.1-1.8 mM effectively inhibit bacterial growth of both E. coli and S. aureus. The β-triketones in mānuka essential oil show potent activity against foodborne pathogens (Listeria, Salmonella, Staphylococcus) and demonstrate virucidal activity against HSV-1 and HSV-2. Notably, bacterial resistance to mānuka honey has not been reported despite its widespread use, likely due to its complex multi-component action.

Anti-inflammatory and Antioxidant: Laboratory studies confirm that mānuka leaf extracts and honey inhibit inflammatory pathways through COX and LOX enzyme inhibition, reducing production of pro-inflammatory mediators. Immunohistochemical analysis shows reduced macrophage activity in wounds treated with mānuka honey, indicating faster transition to tissue remodeling phases. The high flavonoid and phenolic content provides strong free-radical scavenging activity in chemical assays, supporting traditional use for inflamed tissues.

Gastroprotective Effects: Animal models indicate mānuka honey can reduce gastric ulcer formation and support mucosal lining repair through multiple mechanisms including antimicrobial activity against H. pylori, anti-inflammatory effects, and direct protective action on the gastric mucosa. While human clinical trials are limited, preliminary evidence supports traditional use for minor digestive inflammation.

Immune Modulation: In vitro and in vivo studies demonstrate that mānuka honey activates phagocytosis, stimulates B and T lymphocyte proliferation, and modulates cytokine production (TNF-α, IL-1, IL-6), suggesting significant immune-supportive properties beyond direct antimicrobial action.

Western Energetics

Temperature: Cooling to Neutral. Its antimicrobial and anti-inflammatory actions address “hot” conditions such as infection, inflammation, and acute irritation. The honey provides gentle cooling without being excessively cold

Moisture: Drying. Its astringent and antimicrobial properties help resolve “damp” conditions such as weeping wounds, infected sores, and congested mucous membranes. However, when used as honey, it simultaneously provides moisture to tissues

Tissue State: Primarily indicated for Heat/Excitation (infection, acute inflammation, irritation) and Damp/Stagnation (slow-healing wounds, excessive discharge, congestion). The honey’s dual action helps resolve both heat and dampness while supporting tissue regeneration

Taste

Bitter: The dominant taste in the leaf tea, suggestive of its antimicrobial and anti-inflammatory actions. This bitterness stimulates digestive secretions and supports liver function

Pungent: A resinous, slightly camphorous quality in both leaves and essential oil, indicative of the volatile oils and stimulating expectorant properties. This pungency brings warmth and movement to the respiratory system

Astringent: A drying, tightening sensation on the tongue from the tannin content, relating to its tissue-toning and wound-healing effects. This astringency helps “tighten” loose, weeping tissues

Sweet: The honey provides a sweet taste that is nourishing and moistening, balancing the drying nature of the leaf preparations

Plant Lore

Mānuka holds deep significance in Māori culture, where it is known as Kahikātoa or Mānuka. Traditionally, it was one of the most important medicinal plants in rongoā Māori (traditional Māori healing). The leaves were used to make medicinal washes for wounds, burns, and skin conditions; steam baths for respiratory ailments; and decoctions for fevers, colds, urinary complaints, and digestive issues. The hard, durable wood was highly prized for making tools (particularly digging implements), weapons (including clubs and bird spears), and construction materials. The bark was used for waterproofing and in traditional medicines.

Early European settlers, noting the aromatic leaves’ similarity to tea, dubbed it “Tea Tree” after using the leaves to make a tea substitute–though this name can cause confusion with Australian Melaleuca alternifolia (tea tree oil). Captain Cook and his crew reportedly used mānuka leaves to make beer and prevent scurvy during their Pacific voyages.

In Māori tradition, mānuka is seen as a tree of strength, protection, and healing, embodying the rugged resilience of the New Zealand landscape. The plant’s ability to thrive in harsh conditions and pioneer disturbed land made it a symbol of perseverance and regeneration. Some iwi (tribes) have specific protocols around harvesting mānuka, and it’s important to approach this plant with respect for its cultural significance.

The modern “discovery” of mānuka honey’s unique properties in the 1980s and subsequent scientific validation has brought this traditional Māori medicine to global attention, creating both economic opportunities and conservation challenges. The commercialisation of mānuka honey has led to the development of rigorous testing and certification systems (UMF, MGO ratings) to ensure authenticity and therapeutic quality.

Additional Information

Honey Grading Systems: The potency of mānuka honey is graded using several systems:

UMF (Unique Manuka Factor): Reflects the overall antibacterial potency; UMF 10+ is considered therapeutic grade, with UMF 15+ and UMF 20+ indicating progressively higher activity

MGO (Methylglyoxal) Rating: Directly measures methylglyoxal content in mg/kg; therapeutic honey contains >260 mg/kg, with high-grade honey containing >800 mg/kg

NPA (Non-Peroxide Activity): Measures antibacterial activity after hydrogen peroxide is neutralised

Regional Chemotype Variation: Mānuka essential oil composition varies dramatically by region. The East Cape chemotype (North Island) produces oils with >20% (often up to 33%) β-triketones, which is commercially valuable for antimicrobial applications. The Marlborough Sounds area (South Island) produces oils with up to 20% triketones. Other regions may produce chemotypes high in monoterpenes or sesquiterpenes but low in triketones, which have different therapeutic properties and lower antimicrobial activity.

Ecological Role: As a pioneer species, mānuka plays a crucial ecological role in stabilising soils, protecting against erosion, and regenerating native bush. It supports native bird populations (particularly bellbirds and tui, which feed on its nectar) and numerous insect species. Commercial honey production pressure and climate change impacts warrant careful monitoring to protect wild mānuka populations.

Sustainable Harvesting: Given the commercial pressures on mānuka from the honey industry, sustainable wildcrafting of leaves is important. Harvest only from abundant populations, take small amounts from multiple plants, and avoid damaging growing tips. Consider cultivating your own plants if using mānuka regularly.

Authentication Concerns: The global popularity of mānuka honey has led to issues with adulteration and mislabeling. Purchase only from reputable suppliers who provide UMF or MGO certification and can trace the honey’s origin. Genuine mānuka honey contains leptosperin, a marker compound used in laboratory authentication testing.

New Zealand Availability: In New Zealand, mānuka is widely available in the wild, in cultivation, and as commercial products. Fresh leaves can often be harvested year-round. Medical-grade mānuka honey is available from pharmacies, health stores, and directly from certified producers.

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