When Roman soldiers invaded the dank climate of Great Britain, they kept warm by rubbing their chilled arms and legs with nettle, a common weed found along the trails. The hairy spines covering the plant released histamines and formic acid that caused their skin to burn and itch, but the soldiers from Mediterranean climes preferred the irritation to the chill. As far back as biblical times, people throughout Europe practiced urtication, the practice of flogging or swatting themselves with nettle. They believed that by thus injecting irritating chemicals into their skin, they could ease rheumatism and arthritis pain.
Because the histamines in nettle limit the body’s response to pollen and other irritating substances, nettle was also a favored treatment for asthma and allergies. The astringent or constricting quality of the roots and leaves led to its use to stop diarrhea, dysentery, and bleeding.
Old-time herbalists favored nettle for its diuretic action and prescribed it for many urinary tract conditions. Today, several companies in Europe manufacture a nettle extract to combat urine retention caused by an enlarged prostate.
"It was used for a long time as a detoxifying agent, helping to flush the body," says Debra Gibson, N.D., a naturopathic doctor in Woodbury, Connecticut. "A lot of folks drank nettle tea in the springtime when hay fever season came on. It was a spring tonic."
A Worldwide Weed
The common or stinging nettle is a perennial plant and common weed that grows in temperate climates throughout the world. It stands two to three feet high and has dark green, serrated leaves and small, inconspicuous flowers.
Young shoots of nettle are edible when cooked. They contain about the same amounts of beta-carotene and vitamin C as spinach and other greens. Other parts of the plant are used for healing.
In North America, nettle was a popular plant medicine with mainstream physicians throughout the nineteenth century and into the twentieth. A popular medical textbook published in 1928 mentions that people used it to reduce inflammation from sprains and arthritis. Since then, scientists have learned that nettle contains about 20 different chemicals, including lectins, phenols, sterols, lignans, and histamines.
Histamines, which occur naturally in the body, are the culprits behind allergic reactions, says Stanley W. Beyrle, N.D., a naturopathic doctor at the Kansas Clinic of Traditional Medicine in Wichita. When you are exposed to allergens—substances that cause allergic reactions—your body releases histamines, which in turn cause hives, constrict bronchial vessels, and inflame the skin.
The histamines in nettle attach to histamine receptor sites in your cells and keep your body’s histamines from attaching to those cells during an allergic reaction. Nettle’s action is very similar to that of pharmaceutical antihistamine drugs, says Dr. Beyrle.
"What’s important here is that the plant histamines have a less sensitive trigger than the body’s histamines. Although they attach to the receptor sites, they are so weak that they rarely cause any allergic reaction in the person," he says.
SUPPLEMENTSNAPSHOT
| Nettle Botanical: Urtica dioica; also known as stinging nettle. May help: Allergies, rhinitis, urinary problems, asthma, diarrhea, dysentery, hemorrhage, gout, hair loss, and prostate problems. Special instructions: For maximum absorption, take with food. Origin: Found in temperate zones throughout the world; cultivated in Europe. Cautions and possible side effects: Rarely, may aggravate allergy symptoms; if you have allergies, take only one dose a day for the first few days. May cause stomach pain. |
Allergic reactions to nettle itself are rare but not unheard of. Although it is a very benign herb, touching the plant may cause skin irritation similar to an allergic reaction, notes Dr. Gibson.
"People with extreme mold sensitivity should be cautious when using nettle teas, since the leaves may harbor molds that would be ingested," she says. "This is less likely to be a problem with capsules containing the freeze-dried herb or with tinctures." If you have allergies, take only one dose a day for the first few days to avoid aggravating symptoms.
Nettle may help people who have a tendency toward rhinitis, an inflammation of the mucous membranes in the nose that can be brought on by colds, dust, and allergies. Initially, nettle can prevent rhinitis by stifling allergic reactions, but its strong anti-inflammatory properties make it a kind of balm for red, swollen tissues.
In a study of 69 people in Portland, Oregon, researchers found that a freeze-dried extract of the herb was better than a similar but inactive substance (a placebo) at improving the symptoms associated with rhinitis. Some chemicals in the plant also seem to inhibit a destructive enzyme that’s released into tissues during the inflammation.
Turning On the Flow
It’s only been within the last 20 years—and mainly in Europe—that nettle root has been employed in the treatment of benign prostatic hyperplasia (BPH). BPH is a noncancerous enlargement of the prostate gland that constricts the urethra, the tube that leads from the bladder to the penis. Some men with this condition have problems with frequent urination, but they may also have trouble urinating when they have a strong urge. This can be particularly disruptive at night, when the urge to go is like a frustrating alarm clock.
No one is really certain how nettle helps. It’s thought that the herb may limit the amount of testosterone, the male sex hormone, circulating in the blood, or it may inhibit an enzyme, aromatase, that leads to the formation of testosterone. BPH is caused mainly by an overabundance of testosterone, says Dr. Gibson.
Whatever the mechanism, German health authorities have concluded that nettle root extract is an effective treatment for urinary problems caused by BPH, but only when the prostate is slightly to moderately enlarged.
A French study found that men who had to get up several times a night to urinate found significant relief after taking an extract of nettle. Every eight hours, researchers gave a dilute extract of nettle root to 67 patients over 60 years of age. The men with the mildest problems found significant relief in just three to six weeks.
The results were less encouraging for men with more severe cases, as it took a few more weeks before any effect was noticed. Nevertheless, many of the subjects had fewer nighttime awakenings to urinate. The herb did not shrink the prostate but apparently reduced inflammation and swelling.
Commission E, a team of physicians, toxicologists, pharmacologists, and other specialists established by the German government to study herbal medicines, determined that nettle is also a good supportive therapy for inflammatory diseases of the lower urinary tract. All of these scientific conclusions fit with the traditional use of nettle as a diuretic, notes Dr. Beyrle. "This is really one of the great herbs for increasing the secretion of urine," he says. "I’ve also used it to treat chronic inflammation of the bladder."
Freeze-Dried Is Best
Nettle comes as a tincture, capsules, and dried root, from which you can brew a tea. "To get the full benefit of nettle, you really need a freeze-dried extract," says Dr. Beyrle. The freeze-dried preparation is made from nettle that is processed soon after harvesting, he says. Slow drying and processing remove many of the active ingredients.
