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Testosterone performs a number of significant functions in the human body. In both men and women, testosterone governs muscle and bone formation, overall sense of vitality and sex drive. Like any hormone, testosterone has some negative side effects. The popular herbal supplement milk thistle might help to reduce the negative impacts of testosterone. Milk thistle has few known side effects, but can cause allergic reaction in some people. Consult your doctor.

Testosterone Production

In women, the ovaries and the adrenal glands both produce testosterone, according to the website Aphrodite Women’s Health. In men, the testes are responsible for testosterone production. In addition to playing a key role in the development of male sex organs in the womb, testosterone stimulates the changes that occur as boys enter puberty, including increases in penis size, muscle mass and bone density, notes the Merck Manual online. In adult men, testosterone stimulates sperm production.

Secondary Effects

One of the secondary effects of testosterone is acne, according to the late Phyllis A. Balch, certified nutrition consultant and author of “Prescription for Herbal Healing.” By stimulating the skin to produce more oil and increasing the production of the skin protein keratin, testosterone can lead to blocked and infected hair follicles. Dihydrotestosterone, a byproduct of testosterone, thickens and toughens the skin, which can further exacerbate acne. High blood levels of free testosterone — the biologically active form of the hormone — increase the risk of prostate cancer in men, according to the website Daily Science’s report of a 2004 study performed by Johns Hopkins and the National Institute on Aging.

Milk Thistle

A centuries-old herbal remedy for liver complaints, milk thistle has received a relatively large amount of attention from both mainstream medicine and complementary health researchers. The active component of milk thistle is called silymarin, a compound of three antioxidants. Although the quality of studies on milk thistle is mixed, silymarin has proved to protect and promote the growth of liver cells and inhibit inflammation, according to the National Center for Complementary and Alternative Medicine online.

Milk Thistle Action

Milk thistle stimulates the flow of bile. In addition to having positive effects on digestion, increased bile flow helps remove dihydrotestosterone via the stool, potentially easing acne, according to Balch. In “Prescription for Herbal Healing,” Balch reports that one study, performed at the Center of Cancer Causation and Prevention in Denver, found that silibinin — a key antioxidant component of milk thistle — induces prostate cancer cells to return to a normal life cycle, effectively slowing the growth of the cancer.


A 2010 study performed by Ales Vidlar and colleagues at the University Hospital and Palacky University in Olomouc, the Czech Republic, found that, in combination with the nutrient selenium, silymarin helped to significantly reduce low density lipoproteins and total cholesterol — two predictors of prostate cancer progression — in patients who had undergone radical prostatectomy. While mediating the effects of testosterone on prostate cancer, the herb did not reduce testosterone levels in those who took it.