STINGING NETTLE BENEFITS AND SIDE EFFECTS

STINGING NETTLE
BENEFITS side effects, research finds
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Nettle, a leafy plant, grows in most temperate regions. The Latin root of Urtica is uro
which means "I burn". This implies small stings caused by the little hairs on the leaves
of this plant burn when contact is made with the skin. Its root and leaves are used in
herbal medicine.

WHAT HEALTH BENEFITS DOES STINGING NETTLE OFFER?
People have made a good use of nettle. Its tough fibers from the stem have been used to
make cloth and its leaves were eaten as vegetables. People also believe that it may have
health benefits on various conditions such as coughs, tuberculosis and arthritis. With
limited or no scientific support, some manufacturers market it as a stimulant for hair
growth.

It contains lectins and certain types of complex sugars. Lectins and these complex
sugars are probably the major components contributing nettle?s benefits. In vitro studies
demonstrate that its leaf has anti-inflammatory actions, in which preventing
prostaglandin formation [1]. Nettle's root helps benign prostatic hyperplasia (BPH) by
affecting hormones and proteins that carry sex hormones in the body [2]. It was also
found that its freeze-dried leaves reduced sneezing and itching in people with hay fever
[3].

During the allergy season, two to three 300 mg nettle leaf capsules or tablets can be
taken three times a day. For benign prostatic hyperplasia (BPH), 120 mg of a
concentrated root extract has been taken twice a day traditionally [4].

COMMERCIAL PRODUCTS

Most commercial products suggest two to three 300 mg nettle leaf capsules or tablets
three times per day for to reduce allergies during allergy season. For mild benign
prostatic hyperplasia (BPH) in men, most product labels recommend to take 120 mg of a
concentrated root extract in capsules two times per day. However, products for BPH
always combine nettle root with saw palmetto or pygeum extracts.

RESEARCH NOTES ABOUT STINGING NETTLE EXTRACT BENEFITS AND SIDE
EFFECTS

ANTIOXIDANT ACTIVITIES
In a study of Wistar rats, researchers found that stinging nettle supplementation
decreased the free radical concentrations in both cerebellum and frontal lobe. [5]

Turkey scientists studied the antioxidant properties of stinging nettle extracts using
different antioxidant tests, including reducing power, free radical scavenging, superoxide
anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities.
They found that stinging nettle extracts had powerful antioxidant activities. Its antioxidant
activities were comparative to butylated hydroxyanisole (BHA), butylated hydroxytoluene
(BHT), quercetin, and alpha-tocopherol. [6]

ANTI-INFLAMMATORY ACTIVITIES
Stinging nettle?s benefits on inflammation is found (at least partly) related to its inhibitory
effect on NF-kappaB activation. It is because activation of the transcription factor
NF-kappaB is involved in several chronic inflammatory diseases including rheumatoid
arthritis. [9]

ANTI-MICROBIOL ACTIVITIES
Stinging nettle extracts showed antimicrobial activity against nine microorganisms,
antiulcer activity against ethanol-induced ulcerogenesis and analgesic effect on acetic
acid-induced stretching. [6]

ANTI-CANCER CELL ACTIVITIES
The anti-proliferative effect of stinging nettle roots extracts have been observed in in vivo
and in in vitro models.

In a study, researchers prepared the polysaccharide fraction of the 20% methanolic
extract of stinging nettle roots at different concentrations. They found inhibitory effect of
the stinging nettle root extracts on the growth of the lymph node carcinoma of the
prostate during 7 days except the two lowest concentrations. This inhibition was time-
and concentration-dependent. [10]

In another study, researchers investigated the activity of a 20% methanolic extract of
stinging nettle roots on the proliferative activity of human prostatic epithelial (LNCaP) and
stromal (hPCPs) cells. They found a concentration-dependent and significant
antiproliferative effect of the extract only on LNCaP cells during 7 days, whereas stromal
cell growth remained unaltered. On day 4 and 6, the reduction in proliferation of LNCaP
cells showed the minimal effective dose at 1.0E-9 mg/ml. No cytotoxic effect of ME-20 on
cell proliferation was observed. [14]

BENIGN PROSTATIC HYPERPLASIA
Direct implanting of fetal urogenital sinus tissue into the ventral prostate gland of adult
mice led to a 4-fold weight increase of the manipulated prostatic lobe. The induced
growth could be reduced by the polysaccharide fraction of the 20% methanolic extract of
stinging nettle roots by 33.8%. [11]

The effectiveness of stinging nettle extracts is highly dependent on the dose, dosage
form design and duration of supplementation. A 1 year randomized, double-blind,
placebo-controlled multicenter study of 246 patients has demonstrated 459 mg dry
extract of stinging nettle roots was effective to increase Q(max) with limited side effects,
in comparison to placebo. [15] Another study couldn?t shown any benefits of 300 mg
tinging nettle extracts even though 25 mg of pygeum africanum was added into the
supplement. [17]

MECHANISM Japanese researchers prepared the membrane Na+,K(+)-ATPase fraction
from a patient with benign prostatic hyperplasia by a differential centrifugation of the
tissue homogenate. They found that the stinging nettle (Urtica dioica) extracts inhibited
27.6-81.5% of the enzyme activity at 0.1 mg/ml. Steroidal components in stinging nettle
roots, such as stigmast-4-en-3-one, stigmasterol, and campesterol inhibited the enzyme
activity by 23.0-67.0% at concentrations ranging from 10(-3)-10(-6) M. These results
suggest that some hydrophobic constituents such as steroids in the stinging nettle roots
inhibited the membrane Na+,K(+)-ATPase activity of the prostate, which may
subsequently suppress prostate-cell metabolism and growth. [7]

CHRONIC COLITIS
Long-term use of stinging nettle extracts may have benefits on the prevention of chronic
colitis. Researchers induced colitis in C3H.IL-10-/- and BALB/c mice by treating them
with dextran sodium sulfate. They found that stinging nettle leaf extracts could reduce
fewer signs of colitis in these mice. Stinging nettle leaf extracts, furthermore, reduced the
faecal IL-1beta and mucosal TNF-alpha concentrations. [16]

JOINT PAIN/ARTHRITIS
In a study, researchers interviewed 18 patients who used stinging nettle for their joint
pain. Most felt nettle was beneficial to their conditions. [12] Researchers from Germany
found immunomodulating effects of stinging nettle leaf extract. The stinging nettle extract
IDS 23 inhibited lipopolysaccharide but stimulated monocyte cytokine expression. Thus,
stinging nettle extracts may inhibit the inflammatory cascade in autoimmune diseases
like rheumatoid arthritis. [13]

SIDE EFFECTS
Stinging nettle probably is safe with limited side effects. [12]
A frequent cause of contact urticaria is skin exposure to the common stinging nettle
(Urtica dioica). The urticaria is accompanied by a stinging sensation lasting longer than
12 h. There may be substances in nettle fluid directly toxic to nerves or capable of
secondary release of other mediators. [8]

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REFERENCE
[1] Obertreis et al. Antiphlogistic effects of Urtica dioica folia extract in comparison to caffeic malic acid. Arzneimittelforschung
1996;46:52-6. [2] Hirano et al. Effect of stinging nettle root extracts and their steroidal components on the Na+, K+-ATPase of the
benign prostatic hyperplasia. Planta Med 1994;60:30-3. [3] Mittman et al. Randomized, double-blind study of freeze-dried Urtica
dioica in the treatment of allergic rhinitis. Planta Med 1990;56:44-7. [4] Brown et al. BPH and Prostate Cancer Prevention. Seattle;
NPRC, 1997, 9-10. [5] Toldy A et al, The effect of exercise and nettle supplementation on oxidative stress markers in the rat brain.
Brain Res Bull. 2005 May 30;65(6):487-93. Epub 2005 Mar 31. [6] Gulcin I et al, Antioxidant, antimicrobial, antiulcer and analgesic
activities of nettle (Urtica dioica L.). J Ethnopharmacol. 2004 Feb;90(2-3):205-15. [7] Hirano T et al, Effects of stinging nettle root
extracts and their steroidal components on the Na+,K(+)-ATPase of the benign prostatic hyperplasia. Planta Med. 1994
Feb;60(1):30-3. [8] Oliver F et al, Contact urticaria due to the common stinging nettle (Urtica dioica)--histological, ultrastructural
and pharmacological studies. Clin Exp Dermatol. 1991 Jan;16(1):1-7. [9] Riehemann K et al, Plant extracts from stinging nettle
(Urtica dioica), an antirheumatic remedy, inhibit the proinflammatory transcription factor NF-kappaB. FEBS Lett. 1999 Jan
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Oct;65(7):666-8. [12] Randall C et al, Nettle sting of Urtica dioica for joint pain--an exploratory study of this complementary therapy.
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