Nettle (Urtica dioica and Urtica urens) is a perennial herb that grows usually in temperate regions. Many of the species have stinging hairs on their leaves and stems. The needles pump a mixture of formic acid, histamine, serotonin (5-hydroxytryptamine), acetylcholine, moroidin and leukotrienes into the epidermis, producing a stinging or burning sensation.
Nettle Study Results and Health Benefits
The roots stems and leaves of the plant are used for health problems for many including anemia, arthritis, hay fever, allergic rhinitus, urinary tract infection and for an enlarged prostate. Stinging nettle has analgesic effects, and it is frequently used to decrease inflammation and pain in muscles and joints and to treat diseases such as rheumatism and arthritis. Also this plant contains a complex of lectins known as UDA (urtica dioica agglutinin) and different polysaccharides such as arabinogalactans and glucans, which are believed to stimulate the immune system.
Urinary Tract Infection
Stinging nettle may alleviate UTI (Urinary Tract Infection) symptoms by increasing urinary volume and helping to flush bacteria out of the urinary tract. The German Commission E (an official government agency similar to the FDA) approves the use of nettle leaf as supportive treatment in patients with lower urinary tract infections and to prevent and treat formation of urinary gravel.
Benign Prostatic Hyperplasia
Especially useful for men, nettle root plays a key role in promoting a healthful prostate and urinary tract function. Nettle root extracts is used common extent in Europe to treat Benign Prostatic Hyperplasia or BPH. These extracts have been shown to help alleviate symptoms compared to placebo both by themselves and when combined with other herbal extracts. BPH problems include nighttime urination, too frequent urination, inability to urinate, painful urination and irritable bladder. Lignans obtained from nettle roots attach to and alter prostate membranes. This in turn leads to less prostate tissue stimulation, and a decrease in prostate swelling.
Stinging nettle root contains several biologically active chemicals that may influence the prostate indirectly by interacting with sex hormones, or directly by altering the properties of prostate cells. Nettle root has 5-alpha reductase enzyme blocking properties and is thus beneficial for conditions associated with an enlarged prostate, such as frequent or difficult urination. Nettle root has been shown to inhibit the binding of sex hormone-binding globulin (SHBG) to the prostate cell membrane. Stinging nettle root contains chemicals that reduce the production of estrone and estradiol by inhibiting production of an enzyme called aromatase that is needed for their production, according to researchers.
Lab experiments have shown stinging nettle to be comparable to finasteride (Proscar®) in slowing the growth of certain prostate cells. Most of the researches have looked at the effects of a combination preparation that contains both saw palmetto and nettle. Germany Universitätsklinik Essen formally investigated the efficacy of nettle root extract and found the antiphlogistic and antiproliferative properties of the nettle extract to provide a safe treatment option for enlarged prostate. In 2000, German scientists reported a study in the journal Planta Medica after applying nettle root extract to human prostate cells. The nettle root extract significantly inhibited the cells from proliferating, according to the scientists, who concluded that nettle extract contains compounds that are biologically relevant for prostate enlargement and may be beneficial for treating patients with prostate problems.
The polysaccharide fraction, of the 20 percent methanolic extract of nettle roots, was able to decrease the induced growth of prostate gland by 33 % in mice. A 6-month double-blind, placebo-controlled, randomized a study (558 patients 120 mg taken three times daily) demonstrated that 81% of the therapy group experienced relief of lower urinary tract symptoms. At the end of the study period, urine flow rates measurably developed and urine retention in the bladder decreased. In a study in Poland 134 people with symptoms of BPH were assigned to receive 2 capsules of the standard dose of an nettle (300 mg) and pygeum africanum bark extract (25 mg) or two capsules containing half the standard dose, twice daily for 8 weeks. After 28 days of therapy, urine flow, residual urine, and nycturia were significantly decreased in both treatment groups. After 56 days of therapy, further significantly decreased in both treatment groups.
In a study reported in the 2007 International Urology and Nephrology journal, 120 milligrams nettle root extract was given to patients daily for 24 weeks. At the end of the study; revealed 53 % decrease in symptoms with 19 % increase in urinary flow and 44 % decrease in urine retention in the bladder. In a clinical trial, a combination of nettle and serenoa repens (saw palmetto) was just as effective as Proscar (finasteride) in improving symptoms of BPH in a 48-week, double-blind trial, with fewer and milder adverse effects in the herbal group than the drug group. In a randomized, double-blind clinical trial performed by Iranian researchers and reported in 2005 in Journal of Herbal Pharmacotherapy, extracts of nettle significantly improved symptoms of BPH, as measured by the International Prostate Symptom Score. Patients peak flow rates improved by 8.2 milliliters per second and they had a modest reduction in prostate size.
In vitro and animal-based studies demonstrate that stinging nettle extract has anti proliferative activities in human prostate cancer cells and protects against cisplatin-induced toxicity. Preliminary studies shows that an aqueous extract of nettle leaves can reduce adenosine deaminase activity in prostate tissue from men with localized prostate cancer. This plant contains beta-sitosterol. Lab experiments demonstrate beta-sitosterol might have antiproliferative effects on the prostate, by inhibiting growth factors.
Stinging nettle helps decrease symptoms related to hay fever, such as itching and sneezing. In vitro experiments show that stinging nettle extract inhibits different inflammatory events that are responsible for the symptoms of seasonal allergies. One preliminary study showed that nettle helps lessen sneezing and itching in patients with hay fever. Scientists think that may be due to nettle’s ability to decrease the amount of histamine the body produces in response to an allergen. A study of 69 participant reported in “Planta Medica” in 1990 found that taking freeze-dried nettle leaf capsules might ameliorate allergy symptoms. A clinical study was performed to test nettle use in allergies. At the end of the study, 57% of the patients found that the nettle was better than placebo in treating these symptoms. A study investigating the effects of nettle on allergic rhinitus found that 600 mg was able to decrease the adverse effects associated with allergic rhinitis, and that 48% of participants found it better than other over-the-counter drugs. In especially, nettle has been shown to be a histamine antagonist and inhibit mast cell tryptase; two mechanisms of action seen as anti-allergenic.
Nettle leaf is a important natural remedy for anemia. Plant contain high concentrations of chlorophyll, iron and vitamin C. Anemia is a health problem in which the blood has a deficiency of red blood cells or of the hemoglobin these cells need to carry oxygen.
Nettle contains a small-molecular-weight lectin (Urtica dioica agglutinin) purified from the rhizomes, which exhibits antiviral effect and is capable of favourably inducing a immune response. Research findings indicates that this lectin can inhibit a range of viruses including those responsible for colds, influenza and HIV. Scientists from the Pasteur Institute have said that Urtica dioica agglutinin “is an unusual plant lectin that differs from all other known plant lectins . its ability to discriminate a particular population of CD4+ and CD8+ T cells .” Nettle extract may provide preservation against viral infections, according to a research reported in the Feb 2011 edition of the journal “Antiviral Research.” When given on experimental animals, 5 mg per kg body weight of nettles provided important preservation against infection with SARS virus. A Netherlands study found important antiviral activity in stinging nettle extract and noted it may be useful for diarrhea caused by rotavirus infection.
Inflammation and Arthritis
Nettle polysaccharides and caffeic malic acid showed anti-inflammatory effect in vitro and in animal-based studies, via cyclooxygenase and lipoxygenase inhibition. An ethanolic extract was found to suppress HLE (human leukocyte elastase). Human leukocyte elastase is one of the most destructive enzymes released by polymorphonuclear granulocytes, which migrate into tissues during the inflammatory process. In several studies nettle extracts were documented with anti-inflammatory effects as well as to be helpful at relieving arthritis pain and inflammation in humans. Research findings suggests that nettle anti-inflammatory effects are attributed to its ability to interrupt the production and actions of inflammation-producing immune cells in the body. A German study shows that hox alpha, a new extract of nettle leaf, contains an anti-inflammatory substance that suppressed various cytokines in inflammatory joint ailments.
Findings from a some clinical trials suggest positive effects of nettle in the therapy of osteoarthritis of hip, knee and hand. In a study reported in the Journal of the Royal Society of Medicine in June 2000 issue that nettle leaf can decrease osteoarthritic pain in the base of the thumb when applied to the painful area. In a study reported in the Dec 2009 issue of “Arthritis Research and Therapy“, found that a combination of nettles, fish oil and vitamin E reduction the need for analgesics and other drugs to decrease the symptoms of osteoarthritis. Two case studies show topically applied nettle relieves osteoarthritis pain. In a double-blind study, topical applications of nettle and white nettle ( Lamium album; a herb that has evolved to look like nettle, however does not have stinging hairs) were compared. Just stinging nettle (urtica) was associated with relief of arthritic symptoms.
Stinging nettle leaf extracts lessen inflammation, in part, by suppressing the release of inflammatory cytokines. They do this by blocking a chemical inducer known as NF-KappaB, which alters gene expresion. This may be one explanation for the favorable effects has exhibited in rheumatoid arthritis. Using nettles may decrease the need for NSAID (Nonsteroidal Antiinflammatory Drug). In a clinical trial of 37 people with acute arthritis, 50 g of stewed nettle leaf consumed on a daily combined with 50 mg of diclofenac was shown to be as effective as the full 200 mg dose of diclofenac in the therapy of symptoms, over a two week period. In a study, researchers used a nettle leaf extract to observe its effects on dendretic cells. Dendretic cells play an important role in the initiation of rheumatoid arthritis (RA). In 2002 study reported in The Journal of Rheumatology, scientists treated dendritic cells, the cells that are involved in causing inflammatory diseases like rheumatoid arthritis, with nettle extract. The findings was favorable, with the maturation of the dendritic cells being suppressed, which led the scientists to conclude that nettle leaf extract has a therapeutic property on RA. Nettle extract was able to keep dendretic cells from growing, however did not kill the cells. Also the most important observation in this study was that nettle extract had a positive effect against the genes associated with rheumatoid arthritis.
Typical daily dosage include 360 mg aqueous extract, 460 mg dried extract, and 600 mg freeze-dried nettle. One study used 50 g stewed nettle leaf daily for rheumatic problems. Doses of 300 mg of freeze-dried nettle leaf 2 to 3 times per day or 2 to 4 ml of tincture 3 times per day have been used to reduce allergy symptoms. For BPH; 120 mg of root extract three per day (totalling 360mg) or 2 to 4 ml of tincture 3 times per day.