INGREDIENTS & RESEARCH

Nettle

BACKGROUND

Ingredient Type: Botanical, Herb, Extract

Also Known As: Urtica dioica, Stinging nettle, Common nettle, Nettle leaf extract, Nettle root extract

Nettle is a flowering plant native to Europe, Asia, North Africa, and Western North America.  Many well-known varieties of nettle are covered with small hair-like structures known as trichomes.  These trichomes have extremely brittle tips that break off easily when touched.  Once the tips have been removed, nettle trichomes function like miniature hypodermic needles: piercing human or animal skin and injecting a complex mixture of defensive chemicals.  These chemicals cause the unlucky victim to experience a painful stinging sensation that can last for up to 12 hours (1).

These “stinging” trichomes have not, however, deterred humans from using the plant.  Archaeological evidence suggests that bronze-age Europeans used nettle fibers to make clothing (2).  These fibers have also been found in ancient fishing nets, sailcloth, and even paper (3).  Nettle also has a long history as a food and a traditional medicine.  While it's uncertain when humans first started eating nettle, it's believed that they discovered how to negate the effects of the trichomes via cooking thousands of years ago.  Since that time nettle leaf has been used worldwide as a cooked green or a soup additive (4).  The Polish of the 18th century even used it as a staple during times of scarcity (5). 

Ancient reports indicate that Egyptians from 2000 years ago used nettle infusions to relieve arthritis and lumbago pains (3).  Later writings from Greek physicians indicate that nettle was used as a diuretic and a general herbal medicine in the first and second centuries.  Nettle concoctions were later used throughout all of Europe to treat everything from serpent bites, constipation, and gout, to problems with the lungs (3,7).  It has also been used in the folk medicine systems of China, Russia, India, and Africa (6).  Knowledge of the consistent traditional uses of nettle, combined with findings from modern clinical trials, can give us valuable insight into how this interesting plant can be used to improve health.

 

TRADITIONAL USES

The first and second-century Greek physicians Dioscorides and Galen both recommended nettle leaves for the treatment of dog bites, nosebleeds, painful joints, and as a diuretic.  Although the nettle used by the ancient Greeks (probably Urtica pilulifera) was different than that commonly used today, it is a close relative thereof (7,8).  From the twelfth century on, nettle was used in Europe to treat over 50 different ailments.  Some records indicate that: nettle seeds were used for stomach aches; nettle leaf/root were boiled or smoked for lung congestion or asthma; nettle concoctions were used to counter poisons, as diuretics and to treat "bladder stones," gout, and joint aches; and nettle juice was recommended for bloody noses, internal bleeding, or other wounds (3,7).

Throughout history, the traditional medical uses of nettle that appear most consistent include:

  • As a diuretic and for urinary issues  
  • To relieve joint pain and treat osteoarthritis and gout
  • For wound healing and to treat external and internal bleeding

 

WHAT DOES SCIENCE TELL US?

  Nettle Possibly Helps the Joints:

Natural Medicines Comprehensive Database, which claims to be an unbiased scientific information source on complementary and integrative therapies, states that nettle leaf extract is "possibly effective" for osteoarthritis.  They reference one small clinical trial in particular that indicated a reduction in pain for osteoarthritis patients who took oral forms of nettle leaf extract.  This trial administered the extract in conjunction with conventional analgesics and concluded that stinging nettle use "might allow for lower analgesic doses in some patients" (9).

The effect of topical stinging nettle applications for osteoarthritis is much less clear.  A 2013 review concluded that existing placebo-controlled studies of topical stinging nettle leaf show disparate results and are "hampered by design flaws" (10). 

  Nettle Might Help the Prostate and/or Urinary Tract:

There are several trials examining the effect of nettle extract and mixed nettle-containing supplements on the symptoms of enlarged prostate (benign prostatic hypertrophy).  These studies vary widely in their approach and quality and some review papers have noted that there are contradictory outcomes between them.  There are, however; two double-blind, placebo-controlled clinical trials focused on pure nettle extracts that have very compelling results.  One trial involved 246 patients with benign prostatic hyperplasia and the other involved 558 patients.  The 246-patient trial lasted a year and noted much fewer urinary infections in the nettle group during the trial than in the placebo group (3 compared to 10) (11).  They also saw a small, but significant decrease in negative prostate symptoms in the nettle group relative to placebo.  The 558-patient study, which lasted for 6 months, also found significant improvements in negative prostate symptoms in the nettle treatment group relative to the placebo group (4,12).  Because these studies focused on benign prostatic hypertrophy, and therefore also on men, more trials are needed to determine the effect of nettle on the urinary tract of women.  

 

SAFETY

Nettle leaf, roots, or extracts thereof are possibly safe for most people ("some clinical evidence showing its safe use when used appropriately, but evidence is limited") (9).

Interactions:

Major

  •  None reported (9)

Moderate

  • Evidence for moderate interactions is strictly hypothetical at this point.  Because nettle is believed to be a diuretic it might reduce excretion.  This could increase lithium levels in the body beyond what is normally expected in someone taking lithium medications (9).

Side-Effects:

  • When taken orally, nettle or nettle extracts may cause gastrointestinal complaints and, in rare cases, allergic reactions (9,13).

 

REFERENCES

  1. Urtica dioica L. Plants of the World Online from Kewscience. http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:260630-2. Accessed February 21, 2018.
  2. Bergfjord C, Mannering U, Frei KM, et al. Nettle as a distinct bronze age textile plant. Sci Rep. 2012;2:664. doi:10.1038/srep00664.
  3. Kavalali GM. Urtica: the genus urtica. CRC Press. 2004.
  4. Baumgardner DJ. Stinging nettle: the bad, the good, the unknown. J Pat-Centered Research and Reviews. 2016;3(1):48-53. doi:10.17294/2330-0698.1216.
  5. Luczaj L and Szymanski WM. Wild vascular plants gathered for consumption in the Polish countryside: a review. J Ethnobiol Ethnomed. 2007;3:17. doi:10.1186/1746-4269-3-17.
  6. Pant V and Sundriyal RC. Nutritional and therapeutic efficacy of stinging nettle- a review. The J of Ethnolbio and Trad Med. 2106;126:1240-1254.
  7. Bombardelli E and Morazzoni P. Urtica dioica L. Fitoterapia. 1997;68(5):387-402.
  8. Dioscorides. Materia Medica in the Juliana Anicia codex. Austrian National Library in Vienna. 77AD/512AD.
  9. Monograph on Stinging Nettle. Natural Medicines Comprehensive Database. http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=&s=ND&pt=100&id=664&ds=&name=Nettle+(STINGING+NETTLE)&searchid=63269627. Accessed February 21, 2018.
  10. Cameron M and Chrubasik S. Topical herbal therapies for treating osteoarthritis. Cochrane Database Syst Rev. 2013;5:CD010538. doi:10.1002/14651858.CD010538.
  11. Schneider T, Rubben H. Stinging nettle root extract (bazoton-uno) in long term treatment of benign prostatic syndrome (BPS) Results of a randomized, double-blind, placebo controlled multicenter study after 12 months. Der Urologe. 2004;23(3):302-306. doi:10.1007/s00120-004-0532-7.
  12. Safarinejad MR. Urtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomized, double-blind, placebo-controlled, crossover study. J Herb Pharmacother. 2005;5(4):1-11.
  13. Assessment report on Urtica dioica L., and Urtica urens L. herba.  European Medicines Agency. 2008 http://www.ema.europa.eu/docs/en_GB/document_library/Herbal_-_HMPC_assessment_report/2009/12/WC500017975.pdf. Accessed February 22, 2018.

See the Examine.com entry for stinging nettle, the Michigan Medicine Health Library entry for nettle, this European Medicines Agency monograph on Urtica dioica, or the WebMD entry for stinging nettle for more information.