Indications
Allergic rhinitis, musculoskeletal disease such as osteoarthritis, urinary tract infections and inflammation, kidney stones, anemia, diabetes, thyroid disease, and other endocrine disorders. Also, a source of vitamins A, C, and K; potassium; phosphorus; and calcium.
Mechanism of Action
Flavonoids in Urtica dioica have demonstrated anti-inflammatory1 and antioxidant effects,2 particularly the phenolic compounds chlorogenic acid and caffeoylmalic acid and the anthocyanins.3 Urtica spp. also contain β-sitosterol, trans-ferulic acid, dotriacotane, erucic acid, ursolic acid, scopoletin, rutin, quercetin, p-hydroxybenzyl alcohol, dotriacontane, erucic acid, and scopoletin, many of which are credited with antioxidant and anti-inflammatory effects.4 In vitro studies show Urtica extracts reduce lipopolysaccharide-stimulated nitric oxide production by T lymphocytes.5 Urtica spp. contain polyphenol oxidase enzymes shown to affect the activity of catechols, tyrosine, and dopamine.6
Viral infections and elevated viral loads may be implicated in the etiology of some autoimmune disorders including autoimmune thyroiditis. Urtica may have antiviral effects7 and deter viral entry into cells by binding acetylglucosamine glycoprotein receptors.8,9 Urtica agglutinins may inhibit the entry of lymphotropic virus into healthy cells.10 Inhibition of human immunodeficiency virus (HIV) transmission between cells has also been demonstrated.11
Evidence-Based Research
Inflammation in the thyroid may contribute to both hyper- and hypothyroidism. Both whole plant extract and polysaccharide fractions of Urtica have been shown to have an anti-inflammatory effect.12 Urtica has antioxidant, anti-inflammatory, and tissue-tonifying effects on many organs and body systems. Urtica has shown regenerative effects in the brain,13 hepatoprotective effects,14,15,16 anti-inflammatory effects on connective tissues,17 restorative effects in acute pancreatitis,18 and both hormonal balancing and anti-inflammatory effects on the lower urinary tract and prostate.19 Because toxins can also burden the thyroid, a similar mechanism may offer thyroprotection.
A clinical trial showed Urtica to improve total antioxidant capacity and superoxide dismutase levels compared with controls.20 Another clinical trial showed Urtica supplementation to reduce interleukin-6 and C reactive protein in 8 weeks’ time in diabetic subjects.21 Although no studies have been conducted investigating the effects of Urtica on the thyroid or thyroiditis, these findings suggest that Urtica has general and systemic anti-inflammatory effects.
Safety in Pregnancy and Breastfeeding
Urtica is considered safe in pregnancy and lactation, even in food-like dosages.
General Safety
Human clinical trials for diabetes have shown Urtica to be safe and well tolerated.22
Dosage
Diabetes clinical trials have dosed 400 mg every 4 hours.22 However, Urtica spp. are a traditional wild food and have long been eaten in large amounts. Smaller amounts of Urtica are used when in combination with other similarly acting herbs in a formula.
References
Talanta. 2008;77(1):304–13. Combined HPLC-CUPRAC (cupric ion reducing antioxidant capacity) assay of parsley, celery leaves, and Urtica. Yildiz L, Başkan KS, Tütem E, Apak R.
2 J Agric Food Chem. 2007;55(14):5689–96. Antioxidant capacity changes and phenolic profile of Echinacea purpurea, Urtica (Urtica dioica L.), and dandelion (Taraxacum officinale) after application of polyamine and phenolic biosynthesis regulators. Hudec J, Burdová M, Kobida L, Komora L, Macho V, Kogan G, Turianica I, Kochanová R, Lozek O, Habán M, Chlebo P.
3 J Agric Food Chem. 2008;56(19):9127–32. Extraction and HPLC analysis of phenolic compounds in leaves, stalks, and textile fibers of Urtica dioica L. Pinelli P, Ieri F, Vignolini P, Bacci L, Baronti S, Romani A.
4 Zhong Yao Cai. 2007;30(6):662–4. Studies on the chemical constituents of Urtica dioica L. grown in Tibet Autonomous Region.
5 Phytother Res. 2005;19(4):346–8. Stimulation of lymphocyte proliferation and inhibition of nitric oxide production by aqueous Urtica dioica extract. Harput US, Saracoglu I, Ogihara Y.
6 J Enzyme Inhib Med Chem. 2005;20(3):297–302. Purification and characterization of polyphenol oxidase from Urtica (Urtica dioica L.) and inhibitory effects of some chemicals on enzyme activity. Güllçin I, Küfrevioğlu OI, Oktay M.
7 J Ethnopharmacol. 2005;98(3):323–7. Antiviral activity in vitro of Urtica dioica L., Parietaria diffusa M. et K. and Sambucus nigra L. Uncini Manganelli RE, Zaccaro L, Tomei PE.
8 Mol Pharmacol. 2007;71(1):3–11. Carbohydrate-binding agents efficiently prevent dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN)-directed HIV-1 transmission to T lymphocytes. Balzarini J, Van Herrewege Y, Vermeire K, Vanham G, Schols D.
9 Electrophoresis. 2005;26(9):1724–31. Urtica dioica agglutinin: separation, identification, and quantitation of individual isolectins by capillary electrophoresis and capillary electrophoresis-mass spectrometry. Ganzera M, Piereder D, Sturm S, Erdelmeier C, Stuppner H.
10 Antimicrob Agents Chemother. 2008;52(8):2771–9. Inhibition of cell-to-cell transmission of human T-cell lymphotropic virus type 1 in vitro by carbohydrate-binding agents. Balestrieri E, Ascolani A, Igarashi Y, Oki T, Mastino A, Balzarini J, Macchi B.
11 J Virol. 2005;79(21):13519–27. Sugar-binding proteins potently inhibit dendritic cell human immunodeficiency virus type 1 (HIV-1) infection and dendritic-cell-directed HIV-1 transfer. Turville SG, Vermeire K, Balzarini J, Schols D.
12 Crit Rev Food Sci Nutr. 2013;53(5):507–16. Plant food supplements with anti-inflammatory properties: a systematic review (II). Di Lorenzo C, Dell’Agli M, Badea M, Dima L, Colombo E, Sangiovanni E, Restani P, Bosisio E.
13 Folia Morphol (Warsz). 2008;67(3):196–204.The granule cell density of the dentate gyrus following administration of Urtica dioica extract to young diabetic rats. Fazeli SA, Gharravi AM, Ghafari S, Jahanshahi M, Golalipour MJ.
14 Food Chem Toxicol. 2009;47(2):418–24. Effects of Urtica dioica L. seed on lipid peroxidation, antioxidants and liver pathology in aflatoxin-induced tissue injury in rats. Yener Z, Celik I, Ilhan F, Bal R.
15 Phytother Res. 2007;21(11):1039–44. Elevation protective role of Camellia sinensis and Urtica dioica infusion against trichloroacetic acid-exposed in rats. Celik I, Tuluce Y.
16 J Vet Med A Physiol Pathol Clin Med. 2003;50(5):264–8. Effects of Nigella sativa L. and Urtica dioica L. on lipid peroxidation, antioxidant enzyme systems and some liver enzymes in CCl4-treated rats. Kanter M, Meral I, Dede S, Gunduz H, Cemek M, Ozbek H, Uygan I.
17 Clin Rev Allergy Immunol. 2013;44(3):284–300. Scientific basis of botanical medicine as alternative remedies for rheumatoid arthritis. Yang CL, Or TC, Ho MH, Lau AS.
18 Int J Clin Exp Med. 2014;7(5):1313–8. Effects of urtica dioica extract on experimental acute pancreatitis model in rats. Yilmaz B, Basar O, Aktas B, et al.
19 Phytomedicine. 2003;10 Suppl 4:53–5. Long-term efficacy and safety of PRO 160/120 (a combination of sabal and urtica extract) in patients with lower urinary tract symptoms (LUTS). Bondarenko B, Walther C, Funk P, Schläfke S, Engelmann U.
20 Pak J Biol Sci. 2012;15(2):98–102. The effect of hydro alcoholic Urtica (Urtica dioica) extract on oxidative stress in patients with type 2 diabetes: a randomized double-blind clinical trial. Namazi N, Tarighat A, Bahrami A.
21 Pak J Biol Sci. 2011;14(15):775–9. The effect of hydro alcoholic Urtica (Urtica dioica) extracts on insulin sensitivity and some inflammatory indicators in patients with type 2 diabetes: a randomized double-blind control trial. Namazi N, Esfanjani AT, Heshmati J, Bahrami A.
22 Clin Lab. 2013;59(9–10):1071–6. Improved glycemic control in patients with advanced type 2 diabetes mellitus taking Urtica dioica leaf extract: a randomized double-blind placebo-controlled clinical trial. Kianbakht S, Khalighi-Sigaroodi F, Dabaghian FH.