Nettle, or stinging nettle, is a perennial plant growing in temperate and tropical wasteland areas around the world. The plant has been naturalized in Brazil and other parts of South America. It grows 2 to 4 meters high and produces pointed leaves and white to yellowish flowers. Nettle has a well-known reputation for giving a savage sting when the skin touches the hairs and bristles on the leaves and stems. The genus name Urtica comes from the Latin verb urere, meaning 'to burn,' because of these stinging hairs. The species name dioica means 'two houses' because the plant usually contains either male or female flowers.

TRIBAL AND HERBAL MEDICINE USES

In folk medicine nettle plants have been used as a diuretic, to build the blood, for arthritis and rheumatism. Externally it has been used to improve the appearance of the hair, and is said to be a remedy against oily hair and dandruff.

The plant has been widely used by herbalists around the world for centuries. In the first century, Greek physicians Dioscorides and Galen reported the leaf of nettle had diuretic and laxative properties and was useful for asthma, pleurisy and spleen illnesses. Bandages soaked in a leaf and stem infusion were used in early American medicine to stop the bleeding of wounds; an account of this use was recorded by Dr. Francis P. Procher, a surgeon and physician in the Southern Confederacy during the Civil War. Nettle leaves were also recommended as a nutritious food and as a weight loss aid by the famous American plant forager and naturalist, Euell Gibbons.

In Brazilian herbal medicine the entire plant is used for excessive menstrual bleeding, diarrhea, diabetes, urinary disorders and respiratory problems including allergies. Externally, an infusion is used for skin problems. In Peru nettle is used against a variety of complaints such as muscular and arthritis pain, eczema, ulcers, asthma, diabetes, intestinal inflammation, nosebleeds and rheumatism. Externally it is used for inflammations, sciatica, wounds and head lice. In Germany today stinging nettle is sold as an herbal drug for prostate diseases and as a diuretic. It is a common ingredient in other herbal drugs produced in Germany for rheumatic complaints and inflammatory conditions (especially for the lower urinary tract and prostate). In the United States many remarkable healing properties are attributed to nettle and the leaf is utilized for different problems than the root. The leaf is used here as a diuretic, for arthritis, prostatitis, rheumatism, rheumatoid arthritis, high blood pressure and allergic rhinitis. The root is recommended as a diuretic, for relief of benign prostatic hyperplasia (BPH) and other prostate problems, and as a natural remedy to treat or prevent baldness.

The stinging sensation of the leaf hairs is caused by several plant chemicals including formic acid, histamine, serotonin, and choline. In addition to these chemicals, nettle leaf is rich in minerals, chlorophyll, amino acids, lecithin, carotenoids, flavonoids, sterols, tannins and vitamins. The root of the plant has other chemicals such as scopoletin, sterols, fatty acids, polysaccharides and isolectins. Several of nettle's lectin chemicals have demonstrated marked antiviral actions (against HIV and several common upper respiratory viruses). Other chemicals (flavonoids in the leaves and a lectin in the root) have been documented with interesting immune stimulant actions in preliminary research which led researchers to suggest that the lectin might be useful in the treatment of systemic lupus.

Nettle's main plant chemicals include: acetophenone, acetylcholine, agglutinins, alkaloids, astragalin, butyric acid, caffeic acids, carbonic acid, chlorogenic acid, chlorophyll, choline, coumaric acid, folacin, formic acid, friedelins, histamine, kaempherols, koproporphyrin, lectins, lecithin, lignans, linoleic acid, linolenic acid, neoolivil, palmitic acid, pantothenic acid, quercetin, quinic acid, scopoletin, secoisolariciresinol, serotonin, sitosterols, stigmasterol, succinic acid, terpenes, violaxanthin, and xanthophylls.

BIOLOGICAL ACTIVITIES AND CLINICAL RESEARCH

Nettle's long-standing use as an anti-inflammatory aid for rheumatism and arthritis has been confirmed with clinical research. In several clinical studies (including a randomized double-blind placebo trial) nettle leaf extracts were documented with anti-inflammatory actions as well as to be beneficial (and better than placebo) at relieving arthritis pain and inflammation in humans. Research suggests that nettle's anti-inflammatory actions are attributed to its ability to interrupt the production and actions of inflammation-producing immune cells in the body (cytokines, prostaglandins and leukotreines). Another randomized double-blind study was performed on nettle in 1990 which confirmed its traditional uses for allergies and rhinitis (a common inflammatory disorder causing sneezing, nasal congestion and discharge and itchy skin and often triggered by allergies). In this study with 69 patients, nettle extract again rated higher than placebo: 58% reported it relieved most all their symptoms and 48% stated it was more effective than other over-the-counter medications. It was still being confirmed as a beneficial treatment for rhinitis 10 years later when researchers then suggested the same sort of inflammatory immune cell suppression was responsible for the documented effects.

Other recent animal studies with rats (in 2000 and 2002) reported that water extracts of nettle lowered blood pressure, reduced heart rate, and had notable diuretic actions. One of the studies reported that a nettle root extract performed better than the control drug they used (furosemide) at reducing blood pressure, increasing urine output, and increasing sodium excretion. Earlier studies reported nettle had no effect on blood pressure in rats but demonstrated a notable hypotensive effect in cats. It was also shown to have an pain-relieving effect in mice, a sedative effect in rats and mice, as well as to inhibit drug-induced convulsions and lower the body temperature of rats.

The last area of research on nettle focuses on its usefulness for prostate inflammation (prostatitis) and benign prostate hyperplasia (BPH). In more than 20 clinical studies thus far, nettle root (and nettle combined with other herbs) has demonstrated an improvement of clinical symptoms in BPH and prostatitis. (Prostatitis is the inflammation of the prostate gland and surrounding tissues usually caused by a bacteria. BPH is an age-related non-malignant enlargement of the prostate gland due to increased numbers of cells triggered to grow in the prostate.) While nettle's benefit for prostatitis is most probably related to its documented anti-inflammatory properties demonstrated in the arthritis and rhinitis research, it's effect on BPH is quite different - it works on a hormonal level.

BPH, the most common disease of the prostate that generally affects men starting from the age of 40, actually occurs on a hormonal level. Androgens like testosterone as well as estrogens (such as estradiol and estrone) have been shown to cause BPH in animal studies. While testosterone plays a role in BPH, it is rather the conversion of testosterone to the extremely potent dihydrotestosterone that is the problem (and this conversion naturally increases as men age for some unexplained reason). In excess, dihydrotestosterone causes pathological prostate growth. Estrogens, which also increases as men age, influences prostate tissue by stimulating prostate-cell growth. These main hormones travel around the body in a free state, as well as bound to proteins. One such protein is called sex hormone binding globulin (SHBG); its role is to maintain a dynamic hormonal balance in the body. SHBG binds or attaches to hormones and carries them to different receptor sites on cell membranes throughout the body where they can be utilized in different ways. The effect it has depends on which hormone it binds to and which receptor site it is carried to. For instance, in men, estrogen and dihydrotestosterone bound to SHBG, are usually carried to the receptor sites on the prostate gland and once there in excessive amounts, it can stimulate prostate tissue cells to divide and grow rapidly - resulting in BPH.

Some of the more recent research on BPH and nettles indicates that nettle can interfere with or block a number these hormone-related chemical processes in the body that are implicated in the development of BPH. In clinical research, nettle has demonstrated the ability to stop the conversion of testosterone to dihydrotestosterone (by inhibiting an enzyme required for the conversion), as well as to directly bind to SHBG itself - thereby preventing SHBG from binding to other hormones. Other research also reveals that nettles can prevent SHBG that has already bound to a hormone from attaching to the receptor sites on the prostate, as well as to decrease the production of estrogens (estradiol and estrone) by inhibiting an enzyme required for their production.

It all sounds a bit complicated, but basically, most all of the complex intercellular processes required to trigger the prostate to grow new cells and enlarge seems to be inhibited by nettle. This is great news for men suffering from BPH (and there are millions)! Human and animal studies have confirmed these effects and benefits. In one study, a nettle root extract was shown to inhibit the growth of prostate cells by 30% in five days; another reported it inhibited BPH in mice by 51.4% (which suggested it could be used as a preventative as well as a treatment). In a study with 134 men with BPH, 300 mg of nettle root (with 25 mg of another plant called Pygeum) reduced retained urine (blocked by enlarged prostates) and reduced frequent urination at night (a bothersome symptom of BPH) in 28 days. A randomized double-blind clinical trial was conducted with 543 BPH patients who were given a combination of saw palmetto and nettle root or a drug called finasteride. The average urine flow increased in both groups, while urinary urgency and frequency decreased in both groups. Other BPH symptoms also decreased in both groups, and, as usual; fewer side effects were reported by those taking the herbal combination than those taking the drug.

It also should be noted that these same androgen hormones have profound effects on scalp and body hair in both males and females. Hair loss in both men and women has been linked to excessive dihydrotestosterone (DHT) levels. While no clinical studies have been conducted yet on the use of nettle in treating DHT-related hair loss and male pattern balding, research does indicate that nettle root can prevent the conversion of testosterone to DHT. Interestingly, a U.S. patent has recently been filed on an herbal combination containing nettle root for the treatment of male pattern baldness. More research is sure to follow as this is a highly popular and profitable area of research.

Over the last several years, more consumers and practitioners have been learning of nettle's many uses for prostate problems, arthritis and inflammation in general, allergies and hair loss and it follows that more nettle products are showing up on the shelves in stores. Nettle root, nettle leaf and whole herb (leaf, stem and root) products in tablets, capsules, and tinctures are now widely available at most health food stores at very reasonable prices. Consumers just need to remember that the root is much better for BPH and hair loss, while the leaf is better for inflammation (including prostatitis), allergies, and as a natural diuretic for people with hypertension.

Unfortunately, consumers (and even natural product manufacturers) overlook these important distinctions between the root and leaf when searching for natural remedies and products. Nettle is now an ingredient in many herbal formulas for prostate health which are sold in the U.S. market. Pay close attention to the ingredients stated on the labels however; the root is needed for BPH, and the leaves will provide much better results for prostatitis. As a general preventative to prostate problems, for maintaining healthy prostate functions as well as male hormonal levels; clinical research suggests the root will work better than the leaf as well.

Traditional Preparation: Both the root and the leaves are traditionally prepared as infusions. Dosages depend on what one is taking it for. In herbal medicine systems, as a healthy prevention to prostate difficulties or to maintain prostate health, one-half cup of a root infusion 2-3 times weekly is recommended (2-3 ml of a root tincture or 2-3 g of powdered root in capsules or tablets can be substituted if desired). The natural remedy for BPH is one-half cup of a root infusion 2-3 times daily for 30-90 days. (2-3 ml of a root tincture or 2-3 g in capsules or tablets 2-3 times daily can be substituted if desired.) For allergies, inflammation, and hypertension: one cup of a leaf infusion is taken twice daily in traditional medicine systems. This also can be substituted by taking 3-4 g of leaf tablets/capsules twice daily.

Contraindications:

• Nettle has been documented in animal studies to lower blood pressure and heart rate. Those with heart conditions should seek the advice and supervision of a health practitioner to determine if nettle is suitable for their condition and to monitor its effects.
• Nettle has been documented to have diuretic effects. Chronic use of this plant may be contraindicated in various medical conditions where diuretics are not advised. Chronic long-term use of any diuretic can cause electrolyte and mineral imbalances. Consult your doctor if you choose to use this plant chronically for longer than 30 days concerning possible side effects of long term diuretic use.

Drug Interactions: