Nettles (Urtica dioica, also known as stinging nettles), which can reach heights of up to three meters, are very common in temperate zones. They have many health benefits and can add flavor to a wide range of dishes. In addition, nettles are a well-studied medicinal plant with a long tradition dating back to Hippocrates.
Young nettles (harvested in April/May) taste delicious in fresh vegetable juices, sandwiches, spinach salads, and salad dressings; cooked in vegetable dishes and batter; raw and finely chopped in herb butter; and as a dry spice. With their slightly acidic to nutty flavor, nettles go well with other wild herbs (e.g., dandelion greens, wild garlic, and red sorrel) in salads, pestos, and wild herb smoothies. Nettles are also a delicious and healthy addition to tarts, risotto, or spaetzle. Nettle soup is a traditional soup in northern and eastern Europe. Regionally, nettles are used in polenta dishes and puréed foods, and as an addition to special cheeses. Fresh or dried leaves can also be used to make nettle tea. The green seeds (harvested in June/July) taste delicious in sandwiches, and the ripe ones (September) can be toasted and added to wine.
To avoid the unpleasant effects of nettle bristles, wash the nettle leaves and then wrap in a cloth and roll over the cloth with a rolling pin. Drying, soaking, and cooking remove much of the sting from nettles (deactivates the stingers).
In temperate latitudes, nettles (Urtica dioica) are a common weed that grows abundantly in areas where the soil is rich in nutrients. Nettles generally come into bloom between June and October. The young plants that are still low to the ground and have a soft stem are best for cooking as nettles develop oxalate crystals as they mature.1,2
Freshly picked nettle leaves are best kept in a linen bag or a basket so that they are exposed to fresh air. Carefully dried leaves can be stored dry and protected from light in an air-tight container.
Nettles contain phenolic carboxylic acids, flavonoids (mainly quercetin, kaempferol , and isorhamnetin), fat, carbohydrates (polysaccharides), and high amounts of protein. Fresh nettles are rich in minerals and contain significant amounts of magnesium, potassium, iron, and silicon in the form of soluble silicic acid, as well as vitamins A, C, and E.
The roots contain lectins, sterols, coumarins, lignans, and fatty acids.2,4,5 Laboratory analyses show a total of 16 flavonoids and flavonoid and flavonol glycosides in the parts of the nettle plant that are above ground.6
In addition to about 30 % oil (mainly linoleic acid), the seeds contain mucilage, carotenoids, and a high vitamin E content (up to 0.1 %).2
Nettles have astringent, hemostatic, diuretic, detoxifying, and restorative effects.1 The effectiveness of nettle root extract in benign prostatic hyperplasia (BPH) is one of the best studied indications for nettles.7
Dangers / Intolerances:
No significant adverse effects are known for the internal use of nettle extract. Contact with fresh nettles causes stinging and in exceptional cases can lead to severe allergic reactions.7 It is possible that nettle seed extract may influence the effect of concomitantly administered drugs.8
Use as a medicinal plant:
Nettles are traditionally used to treat rheumatic complaints, digestive disorders, and bilious diseases. The slightly diuretic properties of the plant have a positive effect on kidney problems. In traditional medicine, it has been shown that the internal use of nettles increases hematopoiesis and the enzyme productivity of the pancreas. The enzymes and plant hormones in nettles have cancer-preventive effects. Nettles can also lower blood sugar levels, inhibit inflammation, and alleviate prostate problems (roots).2 Stinging nettles can provide alleviation of symptoms in the case of arthritis, gout, sciatica, neuralgia, haemorrhoids, scalp and hair problems, burns, insect bites, nosebleeds, skin complaints, and allergies.1
Other medicinal uses:
All parts of the nettle (i.e., leaves, flowers, roots and seeds) are used for medicinal purposes. In most cases, no distinction is made between nettles and dwarf nettles.4 Nettles are one of the herbal medicines used as a diuretic for flushing therapy in urinary tract diseases and cystitis. Nettle root extracts are used for benign prostate enlargement in men as it leads to an increase in micturition volume and urine flow and reduces the amount of residual urine. Nettles are also used to treat rheumatic disorders.5,9
Urtica dioica is considered to be native to Europe, much of temperate Asia and western North Africa. It is abundant in northern Europe and much of Asia, usually found in the countryside. It is less widespread in southern Europe and north Africa, where it is restricted by its need for moist soil, but is still common. It has been introduced to many other parts of the world. In North America, it is widely distributed in Canada and the United States, where it is found in every province and state except for Hawaii, and also can be found in northernmost Mexico. It grows in abundance in the Pacific Northwest, especially in places where annual rainfall is high. The European subspecies has been introduced into Australia, North America and South America. In Europe, nettles have a strong association with human habitation and buildings. The presence of nettles may indicate the site of a long-abandoned building. Human and animal waste may be responsible for elevated levels of phosphate and nitrogen in the soil, providing an ideal environment for nettles.10
Cultivation and harvest:
Nettle seeds, stolons (runners), and seedlings are generally planted in seedbeds or nurseries in May. The leaves are then harvested when they reach full bloom between the months of August and October. The yield per hectare of cultivated land comes in at a dry mass of 20 to 40 tons or 2.5 to 4 tons of medicinal drug.3
From Wikipedia: Urtica dioica, often called common nettle, stinging nettle (although not all plants of this species sting) or nettle leaf, is a herbaceous perennial flowering plant in the family Urticaceae. Originally native to Europe, much of temperate Asia and western North Africa, it is now found worldwide. The species is divided into six subspecies, five of which have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation upon contact ("contact urticaria"). The plant has a long history of use as a source for traditional medicine, food, tea, and textile raw material in ancient societies.10
The stinging nettle serves various butterflies as caterpillar feed. The caterpillars of the small tortoiseshell, Aglais urticae, Syn .: Nymphalis urticae, need nettle leaves before the flowering of the nettle. The small tortoiseshell is one of the most beautiful butterflies in some areas. It is specialized almost exclusively on the stinging nettle and needs from egg to doll about a month. In warmer climates it can form two or three generations per year and flies from May to October. The small tortoiseshell can be found all over Europe and Asia as far as the Pacific Ocean.11
Literature / Sources:
- Kräuter. Die grosse Enzyklopädie. Anbau und Verwendung. (Herbs. The large enzyclopedia. Cultivation and use). Second edition. Munich: Dorling Kindersly Verlag GmbH; 2015.
- Fleischhauer, Steffen Guido; Guthmann, Jürgen, Spiegelberger, Roland: Enzyklopädie: Essbare Wildpflanzen: 2000 Pflanzen Mitteleuropas. (Encyclopedia: edible wild plants: 2000 plants of Central Europe). First edition. Aarau: AT Verlag; 2013.
- Wikipedia. Grosse Brennnessel. de.wikipedia.org/wiki/ Gro%C3%9Fe_Brennnessel
- Pflanzenmonografien zur Nationalen Datenbank: Die Kleine Brennnessel (Urtica urens) (Herbal monographs for the national databank: dwarf nettles (Uritca urens)).
- Pharmawiki. Brennnessel (Nettles).
- Carvalho AR, Costa G, Figueirinha A, Liberal J, Prior JAV, Lopes MC, Cruz MT, Batista MT. Urtica spp.: Phenolic composition, safety, antioxidant and anti-inflammatory activities. Food Res Int. 2017 Sep;99(Pt 1):485-494. doi: 10.1016/j.foodres.2017.06.008.
- Authors ns: Urtica dioica; Urtica urens (nettle). Monograph. Altern Med Rev. 2007 Sep;12(3):280-4. PMID 18072824
- Agus HH, Tekin P, Bayav M, Semiz A, Sen A. Drug interaction potential of the seed extract of Urtica urens L. (dwarf nettle). Phytother Res. 2009 Dec;23(12):1763-70. doi: 10.1002/ptr.2848.
- Pharmawiki. Brennnesselwurzelextrakt (Nettles extract).
- Wikipedia. Urtica diocica, en.wikipedia.org/wiki/ Urtica_dioica
- Heiko Bellmann: Der Neue Kosmos Schmetterlingsführer, Schmetterlinge, Raupen und Futterpflanzen, S. 172, Franckh-Kosmos Verlags-GmbH & Co, Stuttgart, 2003.