Rare is the herb that grows virtually unnoticed in a field yet makes itself conspicuous by contact. Such is the case with the humble stinging nettle (Urtica dioica), considered a weed by most but now a rising star as stinging nettle benefits include its use as a natural diuretic and a treatment for benign prostatic hyperplasia.
Stinging nettle is a perennial member of the nettle family (Urticaceae). Two varieties of U. dioica are found in North America. The native variety, U. d. var. procera, has male and female flowers on the same plant, whereas those of the European variety, U. d. var. dioica, are on different plants. Plants grow from 2 to 6 feet tall from a creeping rootstock. The square stems of the European variety bear opposite ovate, sharp-pointed, toothed leaves with a heart-shaped base that may reach 6 inches in length. The leaves of the North American variety are narrower and may lack the heart-shaped base. Drooping from the leaf axils, racemes of inconspicuous greenish flowers bloom from June to September. Stinging nettle is found in fields, waste places, and moist thickets.
I learned to identify stinging nettle in a sheep pasture—the hard way. The sheep had left the stands of green, weedy plants alone, and while herding them one summer afternoon clad in shorts, I discovered why. Both the leaves and the fibrous stems are covered with tiny, hollow, silica-tipped hairs that when touched inject an irritant from their bladderlike base. A variety of compounds act in concert to produce the stinging, which usually lasts for about an hour but may persist for up to twelve hours in some individuals. Folk treatments for the sting include rubbing the affected area with either mashed jewelweed leaves (Impatiens pallida or I. biflora), yellow dock leaves (Rumex crispus), or juice from the stems of the nettle. The last treatment might be worth trying, given the obvious availability of the raw materials.
Traditional Stinging Nettle Benefits and Uses
If you can avoid contact with the stinging hairs (wear gloves and long sleeves when harvesting the leaves), you will find stinging nettle to be a plant of many uses. The spring leaves make a tasty spinach substitute when boiled as a potherb and have been used to treat scurvy. They also provide dietary fiber. The dried herb may be sprinkled on salads, soups, vegetables, and other foods for a subtle salty flavor and a rich supply of iron, magnesium, potassium, calcium, vitamins A and C, and protein. (The sting is tamed by cooking or drying.)
European herbal practitioners consider nettle a diuretic, astringent, and treatment for anemia (due to its high iron content). It is also believed to purify the blood and stimulate milk flow. Both the powdered leaves and the fresh juice have been applied to cuts to stop bleeding and taken as a tea to lessen excessive menstrual flow as well as to treat nosebleeds, hemorrhoids, and diarrhea. Nettle tea has also been taken to stimulate blood circulation and to treat mild acne and eczema.
Even the sting has been utilized. Some people used to keep a pot of stinging nettle in the kitchen window in the belief that an occasional sting would alleviate their arthritis, and in King’s American Dispensatory, authors Harvey Wickes Felter and John Uri Lloyd write that paralysis “is said to have been cured by whipping the affected limbs” with fresh nettle leaves.
Stinging Nettle Studies
The diuretic activity of stinging nettle leaves was the subject of a number of German studies during the 1980s. Animals fed stinging nettle in one study excreted more chlorides and urea than controls. Nettle juice given to patients with heart disorders or chronic venous insufficiency for two weeks in another study distinctly promoted urine flow. Researchers have suggested that the herb’s high potassium content and flavonoids contribute to its diuretic action.
It is the roots of stinging nettle that are attracting the most attention from researchers today. German health authorities allow root preparations to be sold for symptomatic relief of urinary difficulties associated with early stages of benign prostatic hyperplasia, the most common prostate condition of aging men. A dose of 4 to 6 grams of herb per day is intended to increase urinary volume while decreasing the urge to urinate at night.
In testing the effects of an extract of the root of U. dioica and an annual European species, U. urens, on sixty-seven men with varying degrees of prostate enlargement, French researchers found that of twelve men who had had to get up twice in the night to urinate, ten no longer needed to get up. Of twenty-seven men who had had to get up three times, thirteen no longer had to get up, and ten had to get up only twice; four showed no improvement. The remaining twenty-eight men, all of whom had had to urinate more than three times a night, showed little improvement.
Several steroids and phenolic compounds have been identified from stinging-nettle root. The steroid stigmast-4-en-3-one has been shown to strongly inhibit an enzyme associated with benign prostatic hyperplasia, leading researchers to postulate that it may thus suppress prostate inflammation. Another enzyme, aromatase, is known to mediate the conversion of androgens to estrogens, which have been implicated in promoting prostate growth. The potential inhibition of aromatase by stinging-nettle components is now under study.
While it will take more research to elucidate nettle leaf’s value as a diuretic and nettle root’s mechanism of action in the treatment of benign prostatic hyperplasia, it is clear that this lowly weed has a greater role to play in health care.
References
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• Bradley, P. R. (ed.). British Herbal Compendium 1. Bournemouth, Dorset, England: British Herbal Medicine Association, 1992.
• Foster, S. Herbal Renaissance. Layton, Utah: Gibbs Smith, 1993.
• Foster, S., and J. A. Duke. A Field Guide to Medicinal Plants: Eastern and Central North America. Boston: Houghton Mifflin, 1990.
• Gansser, D., and G. Spiteller. Planta Medica 1995, 61:138–140.
• Hirano, T., et al. Planta Medica 1994, 60:30–33.
• Leung, A. Y., and S. Foster. Encyclopedia of Common Natural Ingredients Used in Foods, Drugs and Cosmetics. New York: Wiley, 1996.
• Patten, G. Australian Journal of Medical Herbalism 1993, 5(1):5–13.
