Urtica dioica L. · herb
Evidence tier: limited
Anti inflammatory, supports iron levels, and benefits joint health
Different parts, different stories. Nettle root contains beta-sitosterol, a lectin and lignans that in the laboratory bind sex hormone binding globulin and inhibit aromatase and 5 alpha reductase, which is the standard explanation for the prostate effect. The honest position is that the active principle has never been pinned down: reviews state that only a few components of the active principle have been identified and the mechanism of action is still unclear. Nettle leaf contains flavonoids and, in the fresh plant, histamine itself, which is the basis for the antihistamine speculation. None of this rises above hypothesis.
Two different plant parts with two different files, and neither is as strong as the seed implies. Nettle ROOT for lower urinary tract symptoms of benign prostatic hyperplasia is the best supported use and it is modest. A systematic review and meta analysis identified six randomised trials in 1,210 men and found that nettle root improved the International Prostate Symptom Score only SLIGHTLY compared with placebo or usual care, and stated that risk of bias in the included studies was mostly unclear or high. Europe's regulator is the clearest voice here: the HMPC monograph on Urticae radix registers nettle root as a TRADITIONAL herbal medicinal product, for urinary complaints and for lower urinary tract symptoms related to benign prostatic hyperplasia after serious conditions have been excluded by a doctor, on the basis of long standing use, and the assessment states that sufficient data on efficacy are not available. There is a second, bigger problem with the BPH literature that copy must respect: much of it tested nettle root COMBINED with saw palmetto in a fixed combination product, and a result from a two herb product cannot be credited to either herb alone. Nettle LEAF for allergic rhinitis is thin. The trial everyone cites is Mittman 1990, 69 people for one week, with 58 percent rating nettle moderately or highly effective against 37 percent for placebo, which is a weak signal from a small, old, short study. The more recent randomised trial (74 randomised, 40 completing) found symptom scores improved significantly in the nettle group and improved just as much in the placebo group, which is a negative result honestly reported. Nettle leaf for joint pain sits on an EMA traditional use registration only. For iron, energy, blood sugar, hair, testosterone and detox there is no adequate human evidence at all.
Root, as the EMA traditional preparation: 1 to 1.5 g of comminuted root three times daily, or the equivalent extract. Root, as used in the prostate trials: around 120 mg of standardised root extract twice daily. Leaf: no established dose; the rhinitis studies used freeze dried leaf preparations of a few hundred mg daily. Do not use if there is oedema from impaired heart or kidney function, which is EMA's contraindication.
As tea (daily) or capsule with meals.
Generally safe at food and tea doses. Higher dose supplements have diuretic effects, caution with diuretic medications or kidney disease. Fresh leaf may cause skin irritation on contact. May potentiate anticoagulants slightly.
Pregnancy: caution
Breastfeeding: caution
Active compounds: beta-sitosterol, Urtica dioica agglutinin (a lectin), lignans, polysaccharides, flavonoids (leaf)
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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.