Hermetica Superfood Encyclopedia
The Short Answer
Lemon myrtle leaves contain citral isomers—geranial and neral—comprising up to 88.67% of the essential oil, which exert antimicrobial, antioxidant, and anti-adipogenic effects through inhibition of inflammatory mediators and adipogenic transcription factors. In vitro assays demonstrate a DPPH radical scavenging IC50 of 42.57 μg/mL and an EC50 of 20.03 μg/mL in ferric reducing antioxidant power tests, though human clinical trial data remain absent from the published literature.
CategoryHerb
GroupPacific Islands
Evidence LevelPreliminary
Primary Keywordlemon myrtle benefits
Lemon Myrtle — botanical close-up
Health Benefits
**Antioxidant Activity**
The essential oil of Backhousia citriodora exhibits strong free-radical scavenging capacity, with a DPPH IC50 of 42.57 μg/mL and FRAP EC50 of 20.03 μg/mL, attributable primarily to its high citral content and secondary phenolics including gallic acid and ellagic acid.
**Anti-inflammatory Effects**
Leaf extracts suppress nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells, indicating inhibition of the NF-κB-driven inflammatory cascade mediated by geranial and neral components.
**Antimicrobial and Antibiofilm Properties**
Lemon myrtle essential oil demonstrates broad-spectrum antibacterial and antifungal activity consistent with the Myrtaceae family, with citral disrupting microbial membrane integrity and inhibiting biofilm formation on multiple organism types.
**Potential Anti-Adipogenic Effects**
Citral and lemon myrtle essential oil suppressed MDI-induced differentiation of 3T3-L1 preadipocytes and downregulated the expression of key adipogenic transcription factors including PPARγ and C/EBPα, suggesting a mechanistic role in weight management.
**Respiratory Soothing Properties**
Traditional Aboriginal use of lemon myrtle leaves for coughs and respiratory complaints is supported by the known expectorant and antimicrobial properties of high-citral essential oils, which may reduce microbial colonization in the upper respiratory tract.
**Phenolic Antioxidant Load**
Aqueous leaf extracts yield total phenolic content of 35.8–43.9 μg/g, with the highest yield at 80°C for 6 hours; flavonoids such as rutin, luteoloside, and quercetin contribute to vascular protective and anti-inflammatory potential.
**Natural Flavoring and Aromatic Use**
Lemon myrtle is generally regarded as safe as a food flavoring and aromatic agent, with culinary applications providing low-dose exposure to bioactive citral isomers and polyphenols that may contribute to dietary antioxidant intake.
Origin & History
Natural habitat
Backhousia citriodora is a subtropical rainforest tree native to Queensland, Australia, growing naturally along the coastal ranges from Brisbane to Mackay. It thrives in well-drained, fertile soils with high humidity and is now cultivated commercially in plantation settings across northeastern Australia for its leaves and essential oil. Aboriginal Australians have used the plant for generations, and commercial cultivation expanded significantly in the 1990s as global interest in Australian bush foods and botanical extracts grew.
“Backhousia citriodora has been part of Aboriginal Australian cultural and medicinal traditions for thousands of years, with leaves used to address coughs, respiratory ailments, and as an aromatic antiseptic applied topically to wounds and skin conditions. The plant holds cultural significance among Queensland coastal Aboriginal communities who harvested leaves from wild trees within subtropical rainforest ecosystems. European botanical documentation began in the 19th century, with the genus named after the English botanist James Backhouse, and commercial interest in the species grew substantially during the Australian bush food movement of the late 20th century. Today, lemon myrtle is regarded as one of Australia's most commercially significant native botanical ingredients, incorporated into teas, condiments, cosmetics, and nutraceutical products internationally.”Traditional Medicine
Scientific Research
Published research on Backhousia citriodora consists almost entirely of in vitro chemical characterization and cell-based mechanistic studies, with no registered human clinical trials identified in the peer-reviewed literature as of 2024. Gas chromatography-mass spectrometry analyses have rigorously characterized the essential oil composition, identifying 21 compounds representing 98.50% of total oil content, providing a robust phytochemical foundation. Cell culture studies in RAW 264.7 macrophages and 3T3-L1 preadipocytes have generated reproducible mechanistic data, but extrapolation to human physiology is limited by species differences and the absence of pharmacokinetic data in humans. The overall evidence base is preclinical, and while chemically well-characterized, lemon myrtle's clinical efficacy, optimal human dosing, and safety profile in therapeutic contexts require prospective human investigation before evidence-based recommendations can be made.
Preparation & Dosage
Traditional preparation
**Dried Leaf (Culinary/Tea)**
2–4 g) of dried leaf steeped in boiling water for 5–10 minutes; used traditionally for cough relief and as a wellness tea with no standardized therapeutic dose established
Typically 1–2 teaspoons (approximately .
**Essential Oil (Topical/Aromatic)**
Commonly diluted to 1–2% in a carrier oil for topical antimicrobial or aromatic applications; internal use of essential oil is not recommended due to high citral concentration and lack of safety data for oral dosing.
**Leaf Powder (Food Supplement)**
300–500 mg per capsule in commercial Australian bush food supplements; no clinically validated dose exists for therapeutic purposes
Available in encapsulated form at .
**Aqueous Leaf Extract**
Optimal phenolic extraction achieved at 80°C for 6 hours in research settings, yielding 43.9 μg/g total phenolics; commercial extracts vary in standardization and are not uniformly standardized to a specific citral or phenolic percentage.
**Standardized Essential Oil**
Commercial lemon myrtle essential oil is typically standardized to ≥90% citral content; this high concentration mandates significant dilution before any use and is not appropriate for direct ingestion.
**Timing**
No clinical timing data exist; traditional tea preparation is consumed ad libitum, typically 1–3 cups daily in culinary wellness contexts.
Nutritional Profile
Lemon myrtle leaves are nutritionally modest as a whole food but phytochemically rich. The essential oil fraction, representing the primary bioactive component, is dominated by citral isomers (geranial 52.13%, neral 37.65%) alongside minor terpenes including β-myrcene (0.22%), linalool (0.53%), and cyclohexane derivatives. Phenolic compounds in dried leaf aqueous extracts include gallic acid, ellagic acid, catechin, quercetin, rutin, and luteoloside, with total phenolic content of 35.8–43.9 μg/g dry weight depending on extraction conditions. As a culinary herb used in small quantities, lemon myrtle contributes negligible macronutrient intake but delivers meaningful phytochemical diversity; bioavailability of citral and phenolics from food-grade preparations is presumed moderate but has not been formally studied with pharmacokinetic methods in humans.
How It Works
Mechanism of Action
The dominant bioactive constituents, geranial (52.13%) and neral (37.65%), collectively termed citral, act primarily by disrupting microbial cell membranes and inhibiting microbial enzyme systems, accounting for the essential oil's broad antimicrobial profile. In macrophage cell models, lemon myrtle extracts suppress LPS-induced nitric oxide synthesis, likely through downregulation of inducible nitric oxide synthase (iNOS) expression via interference with NF-κB signaling pathways. In preadipocyte models, citral inhibits the MDI-induced upregulation of PPARγ and CCAAT/enhancer-binding protein alpha (C/EBPα), transcription factors essential to lipid accumulation and adipogenesis, suggesting modulation of lipogenic gene networks. Secondary phenolics—gallic acid, ellagic acid, catechin, quercetin, and rutin—contribute antioxidant activity through electron donation and metal chelation, while flavonoids may additionally modulate cyclooxygenase activity to reduce eicosanoid-driven inflammation.
Clinical Evidence
No published human clinical trials specifically evaluating Backhousia citriodora as a therapeutic or supplemental agent were identified in the available literature. Existing studies are limited to in vitro antioxidant assays, cell-based anti-inflammatory and anti-adipogenic models, and essential oil compositional analyses. Preclinical outcomes—including IC50 values for DPPH scavenging and inhibition of adipogenic transcription factors—are promising but cannot be directly translated to clinical effect sizes or human dose-response relationships. Confidence in therapeutic recommendations remains low pending prospective, controlled human trials.
Safety & Interactions
Lemon myrtle and its extracts are generally regarded as safe (GRAS) when used as a food flavoring and culinary aromatic, with a long history of use in Australia without documented adverse events at culinary doses. The essential oil contains very high citral concentrations (>88%) and must be significantly diluted for topical use, as undiluted application may cause skin sensitization, irritation, or allergic contact dermatitis in susceptible individuals; internal use of the concentrated essential oil is not recommended. No formal drug interaction data exist in the published literature; however, given citral's cytochrome P450 modulation potential observed in related monoterpenoids, caution is theoretically warranted with medications metabolized by CYP3A4 and CYP2B6 pathways. Safety during pregnancy and lactation has not been established in clinical studies, and the use of concentrated extracts or essential oil preparations should be avoided in these populations; culinary leaf use is generally considered low-risk.
Synergy Stack
Hermetica Formulation Heuristic
Also Known As
Backhousia citriodoraLemon-scented myrtleLemon ironwoodSweet verbena treeLMEO
Frequently Asked Questions
What is lemon myrtle used for medicinally?
Lemon myrtle leaves have been used in Aboriginal Australian traditions to relieve coughs and respiratory complaints, and topically as an aromatic antiseptic. Modern in vitro research supports antimicrobial, antioxidant, and anti-inflammatory activities driven by its high citral content (up to 88.67% of the essential oil), though no human clinical trials have confirmed these effects therapeutically.
Is lemon myrtle safe to consume daily?
Lemon myrtle is generally regarded as safe (GRAS) as a culinary flavoring and herbal tea, and Australians have consumed it routinely without documented adverse effects at food-grade amounts. Concentrated essential oil preparations are not safe for internal use due to very high citral concentrations; topical use requires dilution to 1–2% in a carrier oil to avoid skin sensitization.
What is citral and why is it important in lemon myrtle?
Citral is a naturally occurring mixture of two aldehyde isomers—geranial and neral—that together constitute approximately 88.67% of lemon myrtle essential oil, making it one of the highest citral-content botanicals known. Citral drives lemon myrtle's antimicrobial properties by disrupting microbial membranes, its antioxidant activity through radical quenching, and its potential anti-obesity effects by suppressing adipogenic transcription factors PPARγ and C/EBPα in cell models.
How do you make lemon myrtle tea?
Lemon myrtle tea is prepared by steeping 1–2 teaspoons (approximately 2–4 g) of dried lemon myrtle leaves in freshly boiled water for 5–10 minutes, then straining and consuming. This method is consistent with both traditional Aboriginal preparation and modern culinary use; research shows that phenolic compound extraction is maximized at 80°C over extended periods, but a standard brew provides meaningful antioxidant polyphenols including gallic acid, rutin, and quercetin.
Does lemon myrtle have any drug interactions?
No formal human pharmacokinetic or drug interaction studies have been published for lemon myrtle or its citral-rich extracts. Theoretical caution is warranted with drugs metabolized by CYP3A4 or CYP2B6 enzymes, as monoterpenoids related to citral have shown cytochrome P450 modulation in preclinical settings. Until dedicated interaction studies are available, individuals on narrow therapeutic index medications should consult a healthcare provider before using concentrated lemon myrtle extracts or essential oil preparations.
What is the difference between lemon myrtle leaf extract and lemon myrtle essential oil?
Lemon myrtle leaf extract is a concentrated form that retains both citral and secondary phenolics like gallic acid and ellagic acid, making it beneficial for antioxidant and anti-inflammatory effects. Essential oil is a highly concentrated volatile fraction composed primarily of citral and other aromatic compounds, offering stronger antimicrobial properties but lower phenolic content than the whole leaf extract. For general health support, leaf extracts provide a more balanced phytochemical profile, while essential oils are typically used for flavoring or aromatherapy due to their potency.
How does lemon myrtle's antioxidant potency compare to other common herbal antioxidants?
Lemon myrtle demonstrates strong free-radical scavenging capacity with a DPPH IC50 of 42.57 μg/mL, placing it among potent botanical antioxidants, though specific head-to-head comparisons with ingredients like green tea extract or curcumin require standardized testing conditions. Its antioxidant effect is driven by both citral content and secondary phenolics including gallic acid and ellagic acid, which work synergistically to neutralize free radicals. Clinical research directly comparing lemon myrtle to mainstream antioxidant supplements remains limited, making it a complementary rather than replacement option.
Who would benefit most from supplementing with lemon myrtle?
Individuals seeking natural anti-inflammatory and antioxidant support, particularly those with inflammatory conditions or oxidative stress-related concerns, may benefit from lemon myrtle supplementation. People interested in digestive or immune support through herbal means could also find value, as traditional use and emerging research suggest these benefits. Those already consuming antioxidant-rich diets may derive minimal additional benefit unless their specific health goals target lemon myrtle's unique phenolic profile.
Explore the Full Encyclopedia
7,400+ ingredients researched, verified, and formulated for optimal synergy.
Browse IngredientsThese statements have not been evaluated by the Food and Drug Administration. This content is for informational purposes only and is not intended to diagnose, treat, cure, or prevent any disease.
hermetica-encyclopedia-canary-zzqv9k4w lemon-myrtle-backhousia-citriodora curated by Hermetica Superfoods at ingredients.hermeticasuperfoods.com and licensed CC BY-NC-SA 4.0 (non-commercial share-alike, attribution required)
