Both human and animal studies link stinging nettle to lower blood sugar levels 26 , 27 , 28 , 29 , In fact, this plant contains compounds that may mimic the effects of insulin In a three-month study in 46 people, taking mg of stinging nettle extract three times daily significantly lowered blood sugar levels compared to a placebo Despite promising findings, there are still far too few human studies on stinging nettle and blood sugar control. More research is necessary.
Consuming dried or cooked stinging nettle is generally safe. There are few, if any, side effects. However, be careful when handling fresh stinging nettle leaves, as their hair-like barbs can harm your skin.
These barbs can inject an array of chemicals, such as 1 , 2 :. Pregnant women should avoid consuming stinging nettle because it may trigger uterine contractions, which can raise the risk of a miscarriage Stinging nettle could interact with these medications.
Stinging nettle ointments are often used to ease osteoarthritis symptoms. The dried leaves and flowers can be steeped to make a delicious herbal tea , while its leaves, stem and roots can be cooked and added to soups, stews, smoothies and stir-frys.
However, avoid eating fresh leaves, as their barbs can cause irritation. That said, studies suggest that the following doses are most effective for certain conditions 14 , 17 :. Studies suggest that it may reduce inflammation, hay fever symptoms, blood pressure and blood sugar levels — among other benefits. While fresh stinging nettle may cause irritation, cooked, dried or freeze-dried stinging nettle is generally safe to consume.
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This article reviews their health benefits and how to grow your own. The sneezing, itchy eyes, congestion, and sinus pressure that come with seasonal allergies — all of these symptoms can become nearly unbearable. Herbal teas have a wide variety of tastes, flavors and even health benefits.
Integrative Medicine. Philadelphia, PA: Elsevier Saunders; chap Bone K, Mill S, eds. London: Churchill Livingstone; A comprehensive review on the stinging nettle effect and efficacy profiles. Part II: urticae radix. Ernst E, Chrubasik S. Phyto - anti-inflammatories. A systematic review of randomized, placebo-controlled, double-blind trials. Rheum Dis Clin North Am. Helms S, Miller A. Natural treatment of chronic rhinosinusitis. Altern Med Rev. Lipophilic stinging nettle extracts possess potent antiinflammatory activity, are not cytotoxic and may be superior to traditional tinctures for treating inflammatory disorders.
Koch E. Extracts from fruits of saw palmetto Sabal serrulata and roots of stinging nettle Urtica dioica : viable alternatives in the medical treatment of benign prostatic hyperplasia and associated lower urinary tract symptoms.
Planta Med. Antiproliferative effect on human prostate cancer cells by a stinging nettle root Urtica dioica extract. Combined extract of Sabal palm and nettle in the treatment of patients with lower urinary tract symptoms in double blind, placebo-controlled trial.
Nahata A. Ameliorative effects of stinging nettle Urtica dioica on testosterone-induced prostatic hyperplasia in rats. Pittler MH. Complementary therapies for treating benign prostatic hyperplasia. Efficacy of a combined Sabal-urtica preparation in the symptomatic treatment of benign prostatic hyperplasia. Results of a placebo-controlled double-blind study.
MMW Fortschr Med. Randomized controlled trial of nettle sting for treatment of base-of-thumb pain. When these toxins are delivered into the skin, a painful itching and burning sensation occurs that may last up to 12 h.
The hairs are naturally designed to protect the plant from insects. Nettles grow all over the world in mild to temperate climates. They prefer open or partly shady habitats with plenty of moisture and are often found in forests, by rivers or streams and on roadsides. Urtica spp. Both species of stinging nettle U. Heavy metals are poorly processed by the plant and tend to accumulate in the leaves. Long vegetation seasons lead to on-going growth, while harsh winters cause destruction of the plants [ 5 ].
Nettles are considered weeds due to their rapid growth and soil coverage. However, there are economic and ecological reasons for cultivating stinging nettles. They can also promote the biodiversity of local flora and fauna [ 6 , 7 ]. Over 40 species of insect are supported by nettles [ 8 ]. Due to their content of tough fibers, nettles were used in Germany and Austria to make textiles during the First World War [ 10 ].
Despite these benefits, most stinging nettles are wild harvested. Different factors affect the chemical composition of nettle plants, such as the variety, genotype, climate, soil, vegetative stage, harvest time, storage, processing and treatment [ 11 , 12 , 13 ].
Stinging nettles are a rich source of nutrients. Chemical composition of nettle leaf powders [ 10 ]. In a study of nettles by Rafajlovska et al. The content of proteins in the leaves ranged from The highest protein contents in the stem and roots were Other studies of nettle composition have found that the plants contain a significant number of biologically-active compounds. The leaves of Urtica spp. Interestingly, more chlorophyll and carotenoids are usually found in plants that have been harvested from shady places.
The concentration of chlorophyll increases in growing leaves and decreases during plant aging. The leaves are also known to contain particularly large amounts of the metals selenium, zinc, iron and magnesium. Rafajlovska et al. These two elements were present at quantities almost three-times higher in the leaves than in the stems and roots. The calcium content expressed in relation to the dry mass ranged from 2. Zinc was found in the highest concentrations in the leaves The mean values for cobalt content were significantly higher in leaves than in stems and roots.
The contents of cobalt in the leaves, stems and roots, respectively, were in the ranges of 0. Urtica leaves in addition contain boron, sodium, iodine, chromium, copper and sulfur [ 14 ]. The total phenolic content of one gram of nettle powder has been reported as mg GAE Gaelic Acid Equivalent , which is two-times higher than the phenolic content in mL of cranberry juice Stinging nettles have been shown to be richer in individual polyphenols than other wild plants [ 13 ].
Ghaima and co-workers found that the content of phenolic compounds in stinging nettle leaves was significantly higher than in dandelion leaves [ 28 ]. Differences in the chemical profiles were found. For example, after Soxhlet extraction, syringic, cinnamic and protocatechuic acids were detected in the products, which was not the case with the UA extract. On the other hand, ferulic, caffeic, chlorogenic and sinapic acids were detected only after ultrasound-assisted extraction [ 30 ].
The polyphenol profiles were dependent not only on the parts of the plants, but also on the location of their acquisition. The researchers found that inflorescence extracts were the richest in phenolics.
The most abundant compound was 5- O -caffeoylquinic acid chlorogenic acid , followed by quercetin 3- O -rhamnosylglucoside rutin and 3- O -glucoside isoquercetin. The quantitative and qualitative composition of the roots differs from that of the aerial parts of the plants [ 22 ].
The content of the majority of the phenols in the root extracts is significantly lower, and the only prominent compound is secoisolariciresinol. Therefore, the roots of stinging nettles are considered to be the poorest part in terms of bioactive compounds. The root extracts contain only a few acids and derivatives in significant amounts Table 3 [ 20 ].
They contain starch, gum, albumen, sugars and resins, as well as neurotransmitters and receptors, such as histamine, acetylcholine, choline or serotonin. Methanolic extracts of nettle roots have an inhibitory effect on aromatase, a key enzyme in the biosynthesis of estrogens. The lipophilic fractions usually contain phytosterols, pentacyclic triterpenoids, coumarins, ceramides and hydroxyl fatty acids. In turn, isolectins and some polysaccharides have been isolated from the hydrophilic fractions [ 31 ].
Krauss and Spitteler identified eighteen phenolic compounds including homovanillyl alcohol, vanillin, vanillic acid and phenylpropanes and nineteen ligands including isolaric, iresinol, secoisolariciresinol and neoolivil in root extracts [ 32 ]. Scopoletin, a coumarin derivative, has also been identified in nettle roots [ 24 ]. All these compounds are considered to be very important in medicine and pharmacology.
For example, homovanillyl alcohol has been shown to protect against cardiovascular disease [ 33 ], while histamine influences the complex physiology of brain systems, affecting cognitive processes, including learning and memory [ 34 ], as well as neurotransmitters involved in neuromodulation processes [ 35 ].
Phytosterols reduce the absorption of cholesterol in the gut and thereby lower blood cholesterol levels [ 36 ]. Scopoletin is a stimulator of lipoprotein lipase activity and protects against cardiovascular diseases [ 37 ]. Lignans improve immune responses [ 38 ]. The phenolic profiles in U. Bolded compounds are those that occur at the highest concentration.
Fresh nettle leaves contain smaller amounts of sterols and higher concentrations of flavonol glycosides. Weglarz and Roslon studied the content of polyphenolic acids in leaves and rhizomes. They found that the level of these compounds was higher in the male forms, but the chemical profiles of polyphenolic acids from the female plants were much more diverse [ 40 , 41 ].
Moreover U. Fifteen hydroxycinnamic acid derivatives and sixteen flavonoids, flavones and flavonol-type glycosides were identified in hydroalcoholic extracts from the aerial parts of U.
Of these, 4-caffeoyl p -coumaroylquinic acid and three statin-like 3-hydroxymethylglutaroyl flavone derivatives were identified for the first time in U. The hairs of Urtica plants contain an acrid fluid with the active components: acetylcholine, histamine and formic acid, as well as silica, serotonin and 5-hydroxy tryptamine.
Many of these chemicals are smooth muscle stimulants [ 44 ]. The fresh hairs of U. The results of numerous experiments suggest that each species of nettle, as well as each part of the plant root, stalk or leaves have a different content and profile of bioactive compounds. Therefore, different species of nettle may have different uses, depending on their chemical characteristics [ 21 ]. Generally, the phenolic composition of plants is affected by different factors, including the variety, genotype, climate, soil, vegetative stage of the plant, harvest time, storage, processing and treatment [ 46 , 47 ].
When and how nettles are harvested strongly determines the final product. During the first year, the stalks are too thin, too ramified and have too many leaves. If the main product is to be the leaves, younger plants are harvested. The time of year for nettle harvesting depends on the purpose. Plants collected in April are used for fodder, medicine or chlorophyll production. Nettles harvested at the end of June are used for fiber production.
The second harvest in September may be used for the collection of leaves [ 7 ]. Nettles possess noticeable antimicrobial activity against Gram-positive and Gram-negative bacteria when compared with standard and strong antimicrobial compounds, such as miconazole nitrate, amoxicillin-clavulanic acid, ofloxacin and netilmicin [ 48 ]. Different fractions of various Urtica species have been studied to determine their antimicrobial activity.
The results indicate the great potential of this plant for the discovery of novel effective compounds Table 4 and Table 5 [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. In vitro activity of Urtica spp.
The results presented in Table 5 show the antimicrobial activities of various nettle extracts obtained by different researchers. These differences appear excessive, and the results should therefore be viewed with caution. Such variations may be associated with the location of the plant habitat and climactic conditions, as well as being due to the use of different extraction techniques and evaluation methods.
Despite their significant differences, however, the results of these studies show that nettle plants exhibit antimicrobial activity against a wide spectrum of microbial strains, often isolated from foods of low microbiological quality. Mahmoudi et al. In recent studies conducted by Antolak et al. On the other hand, Shale et al. Different antimicrobial properties may be the result of the isolation of different compounds in different solvents, of different extraction efficiencies and possibly of chemical degradation by polar and non-polar solvents.
The extraction method, the plant type, the geographical and ecological status, the climate, seasonal and experimental conditions, the age of the plant, environmental stress factors, as well as inter-species differences all play a role and may explain the diversity of results in different studies [ 21 , 65 , 66 ].
Nettles are one of the most commonly-used medicinal plants in the world, due to their health-enhancing qualities. Because of their high content of nutritive substances, nettles are also used in folk veterinary medicine [ 48 , 67 , 68 ]. There are many dietary supplements based on Urtica spp. Their popularity can be explained by their non-toxic chemical composition, relatively low cost and wide availability. The most recognized health benefit of using stinging nettles is activity against Benign Prostatic Hyperplasia BPH , also known as an enlarged prostate, as well as urinary tract infections.
Clinical studies suggest that Urtica spp. In addition, nettle root extract shows activity against prostate cancer cells. In therapy, nettles are usually used in combination with saw palmetto Serenoa repens [ 69 , 70 ].
They are also used as a home remedy for bladder infections. Nettles can help alleviate the symptoms of osteoarthritis and joint pain, typically in the case of hands, knees, hips and spine.
In a study by Randall and co-workers, nettles were able to decrease osteoarthritic pain in the base of the thumb when applied to the painful area.
In a clinical trial of 37 people with acute arthritis, 50 g of stewed nettle leaves consumed daily, combined with 50 mg of diclofenac, were shown to be as effective as the full mg dose of diclofenac over a two-week period [ 71 ].
Studies have also shown that applying nettle leaves directly decreases joint pain and can treat arthritis. In a study by Christensen and Bliddal, it was found that a combination of nettles, fish oil and vitamin E reduced the need for analgesics and other drugs for the symptoms of osteoarthritis [ 72 ].
Another study conducted by Klingelhoefer et al. Nettle leaves contain histamine, which may seem inadvisable for allergy medication.
However, histamine has been already used to treat strong allergy symptoms [ 74 ]. Histamine production causes unwanted allergic reactions, associated with unpleasant nasal congestion, sneezing or itching. In addition, because of their anti-histamine and anti-inflammatory properties, stinging nettles can be used as a natural component in eczema medications. Infusions of the plant can be used for nasal and menstrual hemorrhage, diabetes, anemia, asthma, hair loss and to promote lactation [ 76 ].
Terpenes and phenols are major groups associated with the inhibition of cancers, as well as with the treatment of headache, rheumatism and some skin diseases [ 58 , 77 , 78 ]. Phenols also have been associated with the inhibition of atherosclerosis and cancer, as well as age-related degenerative brain disorders [ 79 , 80 ].
The combination of U. This traditional medicine works on endothelium, blood cells, angiogenesis, cellular proliferation, vascular dynamics and cell mediators to stop bleeding [ 81 ].
In a study conducted by Bourgeois et al. These properties could be ascribed to the ursolic acid and quercetin present in the nettle extracts [ 82 ]. Herb extract of Urtica plants is useful for bladder disorders, reduces postoperative blood loss and prevents hemorrhagic and purulent inflammation following adenomectomy.
Aqueous infusions of U. For a long time, the hypoglycemic effects of U. Recent studies show that nettles possess anti-diabetic properties [ 84 ]. Thus, nettles could serve as good adjuvant to other oral hypoglycemic agents and seem promising for the development of phytomedicines for diabetes mellitus. In addition, as organic nitrogenous compounds, amino acids from nettles are building blocks in the process of protein biosynthesis [ 85 ]. The safety of aqueous extracts of U.
Nettles have traditionally been used as a nutritious food, particularly in spring time in rural areas. In Greek and Roman times, nettle roots were used for meat tenderization. Nowadays, nettles are used in a large number of recipes. Stinging nettles remain popular, especially in poor countries and among the lower socioeconomic classes [ 87 ].
For example, amino acids from dehydrated nettle meal are nutritionally better in comparison to those of alfalfa meal [ 88 ]. These plants may be consumed primarily as a boiled or cooked fresh vegetable, which is added to soups, cooked as a pot herb or used in vegetable salads [ 10 ].
In the temperate region of the Himalayas, U. Upgrowths and leaves are collected with the help of bamboo or iron pincers and cooked as soup. The plants are boiled with maize, millet or wheat flour, with the addition of salt and chili to make a kind of porridge.
Due to their seasonality, U. In European countries, nettles are used in soup or as a steamed or wilted vegetable. Since it has a similar flavor and texture, cooked nettle can be used as a substitute for spinach. Raw nettles after blending can be also used in pesto sauces, salad dressings or dips.
Boiled nettles with walnuts is a common dish in Georgia, while Romanians make sour soup using fermented wheat bran, vegetables and young nettle leaves [ 89 ]. Mature leaves are used in the production of semi-hard Cornish cheese, made from grass-rich milk and wrapped in stinging nettles.
The nettle changes the acidity of the outside of the cheese, affecting the way the curd breaks down and matures. It has also been documented that nettle leaves can be used to coagulate milk in the process of fresh cheese making [ 90 ].
Compared to barley and wheat flour, nettle flour has a much higher content of proteins, crude fibers, fats, ash, calcium and iron and has a low glycemic index. As compared to barley and wheat, nettles have much higher levels of tannins and total polyphenols [ 10 ]. Nettle leaves can also be used to make an herbal tea, which is rich in vitamins and minerals. Depending on the amount used, nettle tea has a mild to strong flavor and tastes similar to vegetable broth. Concentrated nettle tea can be used as a soup base or as a component in drinks or green cocktails.
Nettle tea can also be used as a nutritional replacement for water. Nettle roots can be used as liquid or powdered extracts, as well as in special decoctions. Nettles are also used in herbal liquors [ 91 ]. Learn more about if it's right for you.
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Health Conditions Discover Plan Connect. The Health Benefits of Nettle Tea. Medically reviewed by Gerhard Whitworth, R. What is nettle? Urinary tract health Arthritis and pain Lowers blood sugar Fights chronic disease How to make nettle tea Warnings Takeaway Overview Steeping dried leaves and drinking tea dates back thousands of years.
Urinary tract health. Arthritis and pain.
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