Urtica dioica, commonly called nettle, nettles, or stinging nettle, is often regarded as a noxious weed. Urtica comes from the latin urere, meaning “to burn,” and is the source of the medical term urticaria. Direct contact with the mature plant can break off tiny trichomes or hairs on the leaves and stems, injecting chemicals into the skin that cause long-lasting irritation and stinging. The flowering plant and its roots are used medicinally, and the toxic trichomes are destroyed in processing.
Uses and Benefits:
Nettle is predominately employed in Western cultures for the treatment of arthritis pain, allergies, and benign prostatic hypertrophy (BPH). In European herbal traditions, it is also considered to have diuretic properties. Historical and folk uses of nettle include treatment for diarrhea, constipation, asthma, pleurisy, and eczema; it has also been used as an astringent or hemostatic for nose bleeds, uterine hemorrhage, and the like. The leaves are used for their analgesic, anti-inflammatory, and diuretic properties, while the root is used for its anti proliferative effect on prostatie cells.
The major constituents of the leaves include organic acids (e.g., carbonic, formic, citric), amines, and flavonoid compounds. The stinging source of nettle is in the leaf and stemandular hairs, which contain acetylcholine, serotonin, formic acid, and histamine. The roots containsitosterol and other sterols, lectins, polysaccharides, hydroxycoumarins and lignans. In addition, the plant is rich in amino acids, vitamins, and other nutrients.
Nettle extracts can partially inhibit prostaglandin and leukotriene synthesis in vitro,and have been found to inhibit specific inflammatory mediators such as IL-2, IFN-gamma, and NF-kappa B,l,8
A decreased release of lipopolysaccharide-stimulated TNF-alph, and IL-1 was demonstrated in blood from human volunteers takinu a nettle leaf extract, but other in vitro effects were not validated:
Hormonally responsive prostate tissue is altered in subject Husing nettle root extracts, and this has been attributed to severnl compounds present in the roop, A steroidal-like hydrophobio compound inhibits Na+/K+-ATPase, which can suppress prostatic cell growth, Lignans inhibit the binding of sex hormone-binding globulin (SHBG) to androgens and nettle decreases SHBG serum levels in controlled studies. Specific compounds may also inhibit 5-alpha-reductase or aromatase activity in the prostate, blocking the formation of dihydrotestosterone or estradiol, respectively. Further, polysaccharide fractions of methanolic extracts have anti-proliferative effects on prostate epithelia.
A diuretic effect was observed in rats after intravenous or intraperitoneal injections of a nettle extract, but no effect was observed after oral administration. Parenteral administration of nettle extracts can also cause depression of the central nervous system (CNS), hypotension, and bradycardia in animals.
Many of these studies have been performed in Germany.
Arthritis-The anti-inflammatory/analgesic property of nettle leaf has been used for arthritis symptoms. Topical application appeared to be beneficial in a randomized controlled trial (RCT) for base-of-thumb osteoarthritis; however, the double-blinding (which is difficult to provide for a stinging preparation) was incomplete. Oral preparations were reported to be beneficial in four German studies, primarily in terms of NSAID dose reduction. However, the quality of these studies is questionable because only two were controlled, one randomized, and none blinded.
Allergies-For the treatment of allergic rhinitis, a double-blind RCT in the U.S. evaluated the effect of an orally administered freeze-dried preparation for 1 week. Global assessments of subjective effectiveness were favorable after therapy was completed, but personal diary data revealed only a slightly better outcome than placebo. The large drop-out rate (mainly in the nettle group), unclear dosing, and lack of statistical analysis weaken the results of this study.
Nettle is well tolerated; side effects are generally similar to placebo in the controlled studies. Mild gastrointestinal irritation has been reported, but is uncommon.
Side Effects and Interactions:
Because nettle extract has CNS-depressant effects in rodent toxicity studies, some authorities warn against conmmitant use with CNS depressants. However, it is doubtful that these results apply to humans; there are no reported adverse CNS effects or drug interactions with nettle in the herbal or medical literature.
Uteroactivity has been reported in pregnant and non-pregnant mice, so caution is warranted in pregnant and breast-feeding women. Herbalists have generally found no adverse effects in these populations, however.
Preparations and Doses:
Multiple preparations and formulations of nettle are available, and controlled studies have examined different oral dosing regimens. For the anti-inflammatory effect in acute arthritis, 1340 mg/day of a powdered extract or 50 g/day of stewed nettle leaf was used. For allergic rhinitis, two 300-mg capsules of freeze-dried stinging nettle were dosed 1-7 times per day (mean t.i.d.). For BPH, typical doses are 300-600 mg b.i.lt of a methanol extract of the root. In the herbalist literature, 2-5 g t.i.d. of dried herb is usually taken as an infusion or extract. Topical application of the fresh leaf can be an effective analgesic, as long as the nettle produces a stinging sensation with wheals (it may act as a simple counterirritant), and treatment is repeated daily for several days.
Several clinical trials have found nettle to be beneficial for arthritis pain and BPH symptoms, but poorly designed or unknown study methodology limits the potential benefits reported in these investigations. Minimal clinical evidence is available for the use of nettlo in allergic rhinitis and as a diuretic. As the use of nettle appears to be safe and well tolerated, it is acceptable for patients to try this herb for mild arthritic, allergic, or BPH symptoms. However, the efficacy for any indication remains unproven.
Steve Mathew is a writer, who writes many great articles on herbal medicines for common ailments and diseases. For more information on herbal remedies and home remedies visit our site on health care.