Mentha aquatica

Description

Mentha aquatica, commonly known as water mint, is a perennial herb of the Lamiaceae family that grows naturally in wet environments such as riverbanks, marshes, ditches, ponds and periodically flooded soils. It has quadrangular stems, often reddish at the base, and a vigorous system of rhizomes and stolons that allows it to form dense colonies. Leaves are opposite, ovate to ovate-lanceolate, deep green sometimes with purplish hues, slightly pubescent and characterised by a fresh, penetrating mint aroma with a more herbaceous and “aquatic” profile than peppermint. Inflorescences are terminal or subterminal spikes, sometimes globular, composed of small lilac-pink flowers rich in nectar and highly attractive to pollinators.

• Common name: water mint

• Scientific name: Mentha aquatica

• Family: Lamiaceae

• Genus: Mentha

• Origin: Europe, North Africa, Western Asia; naturalised in many other temperate regions

• Growth habit: perennial, rhizomatous, aromatic herb, often bushy, typical of wet areas

Cultivation and growing conditions

Climate

• Prefers temperate and cool–temperate climates.

• Quite hardy: tolerates winter cold well; the aerial part may die back and sprout again in spring.

• Tolerates cool, humid locations better than dry, very hot conditions.

Exposure

• Prefers bright partial shade.

• Can grow in full sun if the soil remains constantly moist or if it is near water (ditch banks, ponds, streams).

• In full sun and warm climates, it is important to provide plenty of water and, if possible, some shade during the hottest hours.

Soil

• Likes moist or periodically flooded soils, rich in organic matter.

• Adapts to slightly acidic to neutral soils.

• Can also grow in heavy, silty or clay soils, as long as water availability is high.

• In ornamental cultivation it can be grown in pots partially immersed in water at the edge of a pond.

Irrigation

• It is a hygrophilous species: it requires high water availability.

• The soil should never dry out completely; unlike many other aromatic plants, it tolerates waterlogging.

• In pots it must be watered very frequently or placed in deep saucers kept filled with water.

Temperature

• Optimal growth between 15 and 24 °C.

• Tolerates frost well: the rhizomes remain viable in the soil and the plant restarts in spring.

• High temperatures are not a problem if soil moisture remains high.

Fertilization

• Moderate nutrient requirements, but benefits from soils rich in organic matter.

• In spring, work in some mature compost or other organic fertilizer.

• Very high nitrogen inputs are not necessary and can make tissues too soft.

Cultivation care

• Remove old, damaged or overly elongated stems to stimulate new shoots.

• Keep rhizome spread under control: in wet soils it can become very vigorous; use barriers or containers if necessary.

• Keep the area free of weeds, especially in the early stages of growth.

• Monitor for aphids and any fungal diseases under conditions of high humidity and poor air circulation.

Harvest

• Leaves and flowering tops are harvested from late spring to early autumn.

• For maximum aromatic content, harvest just before or at the beginning of flowering.

• Cut shoot tips with clean scissors to encourage new growth and a more compact habit.

• Plant material can be used fresh or dried in a shaded, well-ventilated place away from direct light.

Propagation

• By division of rhizomes or clumps: the simplest and most reliable method, carried out in spring or autumn, ensuring each portion has roots and buds.

• By herbaceous cuttings: in late spring or summer; cuttings root easily in water or in a light, moist substrate.

• By seed: possible, but less used in home cultivation because it gives less uniformity in plant characteristics.

Indicative nutritional values per 100 g (fresh leaves)

• Energy: ~40–60 kcal

• Water: ~80–85 g

• Total carbohydrates: ~8–12 g

  • sugars: ~4–6 g

• Dietary fibre: ~5–7 g

• Protein: ~3–4 g

• Total fat: ~0.5–1 g

  • SFA (saturated fatty acids): very low

  • MUFA (monounsaturated fatty acids): traces

  • PUFA (polyunsaturated fatty acids, n-6/n-3): traces

  • TFA (natural trans fatty acids): negligible

• Vitamins: vitamin C, carotenoids (provitamin A), small amounts of B-group vitamins

• Minerals: potassium, calcium, iron, magnesium, manganese

• Bioactive compounds: essential oil (monoterpenes and oxygenated monoterpenes), polyphenols, flavonoids, organic acids

(Water mint is normally consumed in much smaller quantities than 100 g; values are indicative for compositional reference.)

Key constituents

• Essential oil (chemotype-dependent)

  • menthol, menthone, isomenthone (in some chemotypes)

  • menthofuran (sometimes present at relevant levels depending on population)

  • 1,8-cineole (eucalyptol)

  • terpinyl acetate (in certain populations)

  • limonene, β-caryophyllene and other mono- and sesquiterpenes in minor amounts

• Polyphenols

  • rosmarinic acid

  • caffeic acid and derivatives

  • other phenolic acids (e.g., ferulic, p-coumaric)

• Flavonoids

  • luteolin, apigenin and their glycosides

• Other components

  • chlorophylls, carotenoids

  • plant sterols and triterpenoids in specific extracts

  • organic acids and variable amounts of tannins

Production process

• Cultivation preferably in humid zones or near water bodies, in soils rich in organic matter and with constant water availability

• Propagation by division of clumps or rhizome segments, with rapid soil coverage and need for containment in managed systems

• Harvesting of aerial parts (leaves and flowering tops) near the flowering stage, when essential oil and polyphenol concentrations are highest

• Sorting and cleaning to remove soil, damaged material and foreign matter

• Low-temperature drying (<40 °C) in ventilated, shaded environments to preserve colour, aroma and polyphenolic fraction

• Steam distillation of aerial parts to obtain essential oil, with separation from hydrosol and optional clarification

• Storage of dried herb in tightly closed containers away from light, heat and humidity; storage of essential oil in well-filled dark glass bottles

• Packaging as fresh bunches or trays, sachets or jars (dried herb), or technical bottles (essential oil)

Physical properties

• Perennial herb with quadrangular stems often showing reddish pigmentation; height typically 20–80 cm

• Fresh leaves: ovate, sometimes with weakly crenate margins, herbaceous texture, distinctly minty aroma

• Dried leaves: olive-green turning brownish with time, brittle and lightweight

• Essential oil: clear liquid, colourless to pale yellow, low viscosity, high volatility

• Essential oil density: ~0.88–0.93 g/mL depending on chemotype and temperature

Sensory and technological properties

• Aroma: fresh, minty, balsamic with herbaceous and slightly camphoraceous notes; perceived as “greener” and less sweet than peppermint

• Taste: cooling and refreshing, with a menthol-derived “cold” sensation that becomes pungent at high doses

• Medium-high flavouring power, often used in blends (teas, herbal mixtures) for more balanced aromatic profiles

• Essential oil is sensitive to oxidation (light, heat, oxygen), which alters its aroma and chemical profile over time

• In some food and cosmetic matrices, extracts may contribute to antioxidant and antimicrobial effects depending on formulation and dosage

Food applications

• Herbal teas and infusions, alone or more commonly blended with other herbs (e.g., lemon balm, chamomile, liquorice)

• Traditional flavouring in regional savoury dishes (legumes, vegetables, fresh sauces, condiments)

• Use in refreshing drinks and selected sweet preparations requiring a milder mint profile than peppermint

• Ingredient in natural flavour blends for beverages, herbal preparations and functional products

Nutrition and health

• Contributes vitamin C, carotenoids, minerals and polyphenols to the diet, especially when consumed habitually in herbal teas

• Polyphenols such as rosmarinic acid and flavonoids are associated with antioxidant activity and potential anti-inflammatory modulation in experimental models

• Traditionally used to support digestion, reduce bloating and promote mild gastrointestinal comfort

• Essential oil is sometimes used for topical or inhalation preparations (baths, ointments), always with proper dilution

• Oral use of essential oil requires caution: monoterpene ketones and menthofuran may carry toxicological concerns and must follow regulated limits

Portion note

• Fresh leaves in culinary preparations: approx. 2–10 g per serving

• Dried leaves for infusion: typically 1–2 g per cup, often in blends

• Essential oil: only within formulated foods, supplements or herbal medicinal preparations according to regulations; never ingest pure oil

Allergens and intolerances

• Generally well tolerated at common culinary and herbal dosages

• Possible reactions in individuals allergic to Lamiaceae species

• Essential oil, if undiluted or oxidised, may cause irritation to skin or mucosa in sensitive individuals

• Water mint is not among major regulated food allergens in EU law, although cross-contamination in complex products remains possible

Storage and shelf-life

• Fresh herb: around 3–5 days in the refrigerator (~4 °C) in breathable or perforated packaging

• Dried herb: up to ~12 months if stored airtight and protected from light, heat and humidity

• Essential oil: typical shelf-life 2–3 years in dark glass bottles, well closed; oxidation alters aroma and may increase irritant potential

Safety and regulatory

• All stages of cultivation, handling and processing should comply with GMP and HACCP principles

• Essential oil use as a flavour or cosmetic ingredient is regulated, especially regarding monoterpene ketones and menthofuran

• Ingestion of pure essential oil is not recommended; additional caution is required for pregnant and breastfeeding individuals, children and people with liver conditions or hypersensitivity

• Use in functional foods or supplements requires safety evaluation, approved claims and compliance with dosage and labelling rules

Labelling

• Fresh or dried herb:

  • sales name (“water mint”, “mentha aquatica”)

  • origin, net weight, lot number, best-before date, storage instructions

• Essential oil:

  • botanical name Mentha aquatica, plant part, extraction method (steam distillation), country of origin

  • safety warnings (“for external use”, “do not use undiluted”, “keep out of reach of children”)

• Flavoured foods and supplements:

  • declaration of flavour according to flavouring legislation (e.g., “natural mint flavour”)

• Cosmetic products:

  • appropriate INCI name (e.g., “Mentha Aquatica Leaf Extract”, “Mentha Aquatica Extract”)

Troubleshooting

• Weak aroma in dried herb: may indicate slow or high-temperature drying, exposure to light/air, or unsuitable containers

• Premature browning of leaves: typically caused by excess residual moisture or poor storage conditions; improve drying parameters

• Oxidised or resinous essential oil: caused by exposure to light, heat or repeated bottle opening; reduce storage time and store in cool, dark conditions

• Mint note too weak or too harsh in finished product: may result from under- or overdosing or chemotype variability (menthol/menthone/menthofuran ratios); adjust dosage and standardise raw material

Sustainability and supply chain

• Mentha aquatica is rustic and well adapted to wetland environments, requiring limited external inputs when grown appropriately

• Can contribute to phytoremediation and vegetative filtration systems by absorbing nutrients and certain pollutants, thereby improving water quality

• Steam distillation generates wastewater and spent biomass; sustainable management includes monitoring BOD and COD and valorising biomass as compost or bioenergy feedstock

• Short supply chains, local harvesting and processing reduce transport-related environmental impact and enhance local resource value

Main INCI functions (cosmetics)

• fragrance / perfuming – provides fresh, minty, slightly herbaceous notes

• skin conditioning – contributes to a fresh, pleasant skin feel in gels, lotions and cleansing products

• masking – helps reduce undesirable odours from other raw materials

• refreshing / tonic – associated with cooling and invigorating sensations on skin and scalp

• antioxidant – polyphenol-rich extracts may support product stability and provide mild protective effects on the skin

• purifying / decontaminating – used in formulations aimed at skin exposed to pollutants or impurities

Conclusion

Mentha aquatica is a distinctive mint species adapted to wetlands, offering a fresh, herbaceous and clearly mentholated aromatic profile. Its phytochemical richness makes it suitable for culinary, herbal and cosmetic uses, and its traditional digestive and refreshing properties are supported by experimental evidence of antioxidant and antimicrobial potential. Beyond its organoleptic value, the plant plays an ecologically relevant role in water-rich environments and can be integrated into sustainable supply chains. Essential oil use requires strict adherence to safety and regulatory guidelines, but when properly managed, water mint represents a versatile, high-value botanical resource.

Mini-glossary

• SFA – Saturated fatty acids: fats with no double bonds; high intake relative to unsaturated fats may increase cardiovascular risk.

• MUFA – Monounsaturated fatty acids: fats with one double bond; considered beneficial when replacing saturated fats.

• PUFA – Polyunsaturated fatty acids: fats with two or more double bonds (n-6/n-3 families); support normal heart function in a balanced diet.

• TFA – Trans fatty acids: fats with at least one trans double bond; intake should be kept very low, though water mint contains only natural trace amounts if present.

• GMP – Good manufacturing practices: hygiene and quality standards ensuring proper production and handling.

• HACCP – Hazard analysis and critical control points: preventive system for identifying and controlling safety hazards in food and related supply chains.

• BOD – Biological oxygen demand: indicator of biodegradable organic load in wastewater.

• COD – Chemical oxygen demand: indicator of total oxidisable substances in wastewater.

Studies

This study examined the content of mentha aquatica and confirmed the antioxidant and antibacterial activity of methanol and chloroform extracted from the plant's aerial parts as well as other polyphenol compounds, sterols and triterpenoids (1).

The neuroprotective activity of mentha aquatica was detected in research aimed at studying the potential activities of traditional medicinal plants on the central nervous system. Among four species of mint (Mentha aquatica, Mentha longifolia, Mentha pulegium, Mentha suaveolens and M. x piperita), mentha aquatica has shown better neuroprotective results (2).

Sixteen edible plants in southern Italy have been evaluated for their anti-proliferation properties in vitro. Aquatic mint showed selective anti-proliferation activity in breast cancer (3).

Mentha aquatica studies

References_________________________________________________________________________

(1) Ferhat M, Erol E, Beladjila KA, Çetintaş Y, Duru ME, Öztürk M, Kabouche A, Kabouche Z. Antioxidant, anticholinesterase and antibacterial activities of Stachys guyoniana and Mentha aquatica. Pharm Biol. 2017 Dec;55(1):324-329.

Abstract. Context: Stachys guyoniana Noë ex. Batt. and Mentha aquatica L. are two Algerian Lamiaceae used in folk medicine. Objective: To investigate their antioxidant, anticholinesterase and antibacterial activities. Material and methods: n-Butanol (BESG), ethyl acetate (EESG) and chloroform (CESG) extracts of S. guyoniana and methanol (MEMA) and chloroform (CEMA) aerial part extracts of M. aquatica and methanol (MERMA) and acetone (AERMA) roots extracts of M. aquatica were evaluated for their antioxidant activity by the β-carotene-linoleic acid, DPPH• and ABTS•+ scavenging, CUPRAC and metal chelating assays. The anticholinesterase activity was tested against AChE and BChE. The antibacterial activity was assessed by MICs determination against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella heidelberg, Klebsiella pneumoniae, Enterobacter aerogenes and Morganella morganii strains. Results: In the β-carotene test, the CESG (IC50: 2.3 ± 1.27 μg/mL) exhibited the highest activity. The BESG was the best scavenger of DPPH• (IC50: 2.91 ± 0.14 μg/mL). In the ABTS test, AERMA was the most active (IC50: 4.21 ± 0.28 μg/mL). However, with the CUPRAC, the BESG exhibited the best activity (A0.50: 0.15 ± 0.05 μg/mL) and was active in metal chelating assay with 48% inhibition at 100 μg/mL. The BESG was the best AChE inhibitor (IC50: 5.78 ± 0.01 μg/mL) however, the AERMA showed the highest BChE inhibitory activity (IC50: 19.23 ± 1.42 μg/mL). The tested extracts exhibited a good antibacterial activity. Conclusion: This study demonstrated good antioxidant, anticholinesterase and antibacterial potential of S. guyoniana and M. aquatica, which fits in well with their use in folk medicine.

(2) López V, Martín S, Gómez-Serranillos MP, Carretero ME, Jäger AK, Calvo MI. Neuroprotective and neurochemical properties of mint extracts. Phytother Res. 2010 Jun;24(6):869-74. doi: 10.1002/ptr.3037.

(3)  Conforti F, Ioele G, Statti GA, Marrelli M, Ragno G, Menichini F. Antiproliferative activity against human tumor cell lines and toxicity test on Mediterranean dietary plants.  Food Chem Toxicol. 2008 Oct;46(10):3325-32. doi: 10.1016/j.fct.2008.08.004.

Abstract. Sixteen edible plants from Southern Italy were evaluated for their in vitro antiproliferative properties, using the sulforodamine B (SRB) assay, on four human cancer cell lines: breast cancer MCF-7, prostate cancer LNCaP, amelanotic melanoma C32 and renal adenocarcinoma ACHN. After 48 h of incubation the most antiproliferative plant extract was Cynara cardunculus ssp. cardunculus on C32 and ACHN cell lines with IC(50) of 21 and 18 microg/ml, respectively. Mentha aquatica showed a selective antiproliferative activity on breast cancer while significant activity was exerted by Cichorium intybus on melanoma. These species contained the highest amount of phenolics. The acute toxicity of the hydroalcohol extracts from all the plants were evaluated by using the Microtox acute toxicity test. This bacterial test measures the decrease in light emission from the marine luminescent Vibrio fischeri bacteria when exposed to organic extracts. This inhibition test was revealed to be highly sensitive, cost effective and easy to operate, requiring just 15 min to predict the sample toxicity. All the extracts analyzed resulted to give values very less than a limit of 20% value, demonstrating so an irrelevant toxicity for the human health. In contrast, Echium vulgare and Malva sylvestris showed bioluminescence inhibition values of 19.42% and 17.32%, respectively, just under the established limit.