Stinging nettle extract is derived from the leaves and root of the plant, and is often used to treat anemia because the nettle leaves contain high concentrations of iron. In terms of body building, nettle extracts appear to impact the level of testosterone in the body. Testosterone tends to become “bound” to the sex hormone-binding globulin — SHBG — but it is more useful and less harmful when it is free to circulate. According to Bastyr University, nettle extract binds to SHBG by taking the place of testosterone, which is then free to roam.
Testosterone is concentrated in muscle tissue. By keeping testosterone freely moving in the body, an increase in free flowing testosterone may increase your level of muscle strength and the amount of lean muscle. There are anecdotal reports that nettle extract also helps to replenish the amount of testosterone in the body, which can be dramatically diminished during a body building workout; However, these claims have not been scientifically verified. According the University of Maryland Medical Center, clinical research demonstrates that stinging nettle relieves the symptoms of an enlarged prostate, but it doesn’t shrink the prostate, so its mechanism of action is still unclear.
Nettle extract is generally safe, with side effects including mild upset stomach and fluid retention. However, in commercial preparations, nettle extract is often combined with other supplements that are not so beneficial. The bodybuilding website Truly Huge touts Andro-Shock, a supplement containing nettle root extract, as one of “10 powerful testosterone boosters in one.” The ingredients also include tonkatali, DHEA and bulgarian tribulus terrestris, which can drive up testosterone levels.
While nettle root extract may decrease the risk of prostate problems, in part by freeing up testosterone, body builders run risks by driving up their testosterone levels. Side effects of excessive testosterone can include: adverse effects on cholesterol; headaches; anxiety; irritability; rage; decreases in libido and increases in the risk of cancers, including prostate cancer. If you are a body builder, you should consult a medical expert about nettle root supplement and any other supplements you are taking. Taking nettle root extract may also interfere with prescription drugs, another reason to consult your health care provider before using the extract.