Stinging Nettle for Testosterone

Popular traditional herb stinging nettle may have multiple T-boosting bio-activities.

Stinging nettle is a common plant prized in herbalism for its variety of health-supportive properties. In the context of testosterone, research suggests that stinging nettle root’s bio-active compounds may work by:

• Inhibiting aromatase, an enzyme which converts testosterone to estrogen.
• Inhibiting 5a-reductase, an enzyme which converts testosterone to its metabolite dihydrotestosterone (DHT).
• Binding with SHBG, a protein which normally binds to testosterone and makes it inactive.

Overview

Urtica dioica, also known as stinging nettle, is a flowering plant that has been used since antiquity as a wellness herb and food source. The ancient Greeks, for instance, used it as a laxative and diuretic, while both European and Asian peoples ate its boiled shoots for sustenance. It was also employed to make cordage for weaving, fishing, and sailing.¹

Stinging nettle gets its name from the fact that its leaves and stems are coated with tiny stinging hairs which can release several irritating chemicals onto the skin, causing a painful burning sensation, redness, and other possible symptoms including swelling, itchy bumps, and a rash.² Curiously enough, applying nettle to an already painful area of the body could actually decrease the pain, which has historically been one of its major uses.³

Stinging nettle is significant for its role as a global folk herb, used for centuries to help with everything from diarrhea to asthma.⁴ Although other plants under the Urtica genus are also believed have health-supportive uses, Urtica dioica — Stinging Nettle — is by far the most used and well-known.

In modern herbal practices, stinging nettle is primarily used to help with men’s health concerns. It is especially popular for helping to maintain a normal prostate size, which can in turn help with urinary health and sexual performance in men.

Stinging nettle root is also being investigated as a potential testosterone booster. Let’s look into some of the ideas behind nettle’s roles in testosterone levels.

Nettle’s Possible T-Boosting Bio-Activities

Stinging nettle root appears to have three main actions which could theoretically increase testosterone levels. Although these mechanisms show a lot of promise, most of the findings thus far are restricted to studies done with isolated compounds rather than whole, living organisms.

Inhibition of aromatase

Nettle blocks aromatase, an enzyme required to convert testosterone into estrogen. As a result of this action, stinging nettle could theoretically reduce estroge­­­n and increase testosterone levels at the same time. In fact, a whole class of drugs with this effect already exists: Aromatase inhibitors (AIs). AIs are used to treat a variety of sex hormone-related disorders in men, and appear to be effective at increasing testosterone levels in older men.⁵⁶ Nonetheless, this bio-activity remains in question due to lack of human research and because nettle contains relatively small amounts of the aromatase-inhibiting compounds.⁷

Binding SHBG

Stinging nettle also contains compounds known as lignans, which have the ability to bind with sex hormone-binding globulin (SHBG), a protein required to transport and store sex hormones in the bloodstream. The­ majority of testosterone is bound to SHBG and cannot be used by the body; only about 2% remains free and active. By binding with SHBG, lignans could thus theoretically increase free testosterone levels in the blood.

• Bonus: Stinging Nettle’s ability to block SHGB has also been suggested as one of the bio-activities that makes the herb so effective at maintaining normal prostate size.

Inhibiting 5-Alpha-Reductase

The third significant activity of stinging nettle appears to be inhibition of the enzyme 5a-reductase, which is required to convert testosterone into one of its more potent metabolites — dihydrotestosterone (DHT). In doing so, nettle could further boost active testosterone levels.⁸ Furthermore, given that elevated DHT is associated with the development of benign prostatic hyperplasia and male pattern baldness, stinging nettle could potentially be even better than a simple T-booster. Despite this, it is important to keep in mind that since DHT is also a sex hormone with many functions in the body, this activity could possibly be counter-productive.

The bottom line is that more research is needed to provide a conclusive answer for all 3 of these suggested mechanisms of action.

Research

Animal Research

Animal trials have shown stinging nettle to boost testosterone levels in rats.

Stinging nettle root extract appears to increase testosterone levels in rats with BPH by preventing its conversion to DHT

This study looked at the effects of stinging nettle on benign prostatic hyperplasia (BPH) in rats caused by testosterone administration. Rats were split into multiple groups: no treatment, testosterone only (T), T plus drugs used to treat BPH, and T plus varying concentrations and extract forms of stinging nettle root for 28 days.

All stinging nettle groups had significantly higher (25-45%) testosterone levels than the testosterone treatment alone after 28 days. The researchers explained this by nettle’s inhibition of the enzyme 5a-reductase, which converts testosterone to dihydrotestosterone (DHT).

• The researchers concluded that “Measurement of prostate/body weight ratio, weekly urine output and serum testosterone levels, prostate-specific antigen levels (on day 28) and histological examinations…led us to conclude that UD can be used as an effective drug for the management of BPH”⁹

Human Research

Human studies of stinging nettle as a testosterone booster are largely limited to in vitro work, meaning that the research has only been performed with isolated compounds rather than complete, living organisms. Furthermore, the only major study in human patients reported negative results.

Compounds found in stinging nettle root appear to reduce activity of aromatase, an enzyme which converts testosterone to estrogen

The goal of this study was to examine whether compounds isolated from stinging nettle could inhibit aromatase—an enzyme needed to convert testosterone to estrogen. After isolating 5 individual compounds from dried nettle roots, the researchers mixed compounds one-by-one in a solution with biological material containing aromatase. All 5 compounds were found to be effective, with aromatase inhibition ranging from 11-24%.

• The researchers concluded that “Methanolic extracts of stinging nettle (Urtica dioica L.) roots were investigated for aromatase inhibition…Inhibitory effects on aromatase could be demonstrated in vitro for a variety of compounds belonging to different classes”¹⁰

Lignans found in stinging nettle roots may increase blood testosterone levels by binding to sex hormone-binding globulin (SHBG)

This study investigated the interaction of plant compounds known as lignans with SHBG, a protein which transports and stores testosterone and other sex hormones. When SHBG is bound to these hormones, they cannot be used by the body.

The researchers isolated multiple lignans from nettle root extract and tested them separately in a solution containing SHBG and dihydrotestosterone (DHT), one of the male sex hormones. They found that all but one lignan compound bound to SHBG, resulting in less SHBG being available to bind with DHT. The most potent of these lignans, 3,4-divanillyltetrahydrofuran, was able to prevent 95% of DHT from binding.

• The researchers concluded that “Lignans may influence the blood level of free, i.e., active, steroid hormones by displacing them from the SHBG binding site”¹¹

Stinging nettle does not appear to increase testosterone levels in men with benign prostatic hyperplasia

The goal of this study was to examine the effects of stinging nettle (Urtica dioica) on symptoms of benign prostatic hyperplasia (BPH). A total of 558 patients were given either nettle or placebo treatment over 6 months. Although nettle was effective at treating BPH symptoms, there was no difference in testosterone levels between placebo and nettle treatment.

• The researchers concluded that “Serum PSA and testosterone levels were unchanged in both groups… Urtica dioica have beneficial effects in the treatment of symptomatic BPH”¹²

Dosage Notes

No current recommendations exist for the appropriate dosage of stinging nettle for boosting testosterone. However, dietary supplements (of stinging nettle root) typically recommend 250-750 mg per serving.

Side Effects

Stinging nettle may lead to minor side effects such as an upset stomach and sweating. But overall, nettle is regarded as safe and well-tolerated, with very low risk for side effects or toxicity.¹³

Available Forms of Nettle Urtica

Stinging nettle is sold in many different forms, including dried or freeze-dried leaf, root extracts, capsules, tablets, and even juice and tea. Other forms:

• Standardized Stinging Nettle: May supply 1% silicic acid
• Concentrated Extract: Commonly presented as a 10:1 herbal concentrate, though may range as high as 50:1

References