As men grow older, they often face daunting health challenges caused by the age-related decline in testosterone levels. As levels of free testosterone dwindle and estrogen levels increase, many men experience diminishing energy levels, reduced libido, decreasing muscle mass, deteriorating mood, abdominal obesity, and perhaps even faltering cognition. At the same time, they become increasingly prone to benign prostatic enlargement (BPH) and prostate cancer.
Testosterone replacement drug therapy has gained enormous popularity in recent years. Those who choose this method need to find a doctor willing to prescribe a testosterone cream drug that is then rubbed into the skin each day.
Alternatively, there are natural testosterone-boosting methods that have been around for centuries. Plant extracts such as chrysin and certain plant lignans inhibit the aromatization (conversion) of testosterone to estrogen, effectively enhancing free testosterone levels. Nettle root liberates testosterone in the body by preventing it from being bound to sex hormone-binding globulin.
Lignans have also shown promising results against prostate cancer, while plants like muira puama have been shown to improve desire and performance, allowing aging men to recapture their sexual pleasures.
This article discusses how men can regain much of their youthful vigor, body composition, and sense of well-being by using plant extracts to naturally restore their testosterone levels.
Aging-Related Hormonal Changes in Men
After peaking in his 20s, a man’s levels of the sex hormone testosterone tend to gradually decrease and continue to further decline throughout the remainder of his years. This decrease is often accompanied by closely related changes in everything from skin tone and lean muscle mass, to a gradual erosion of libido and the beginning, in some cases, of erectile dysfunction. Although the evidence is preliminary, it appears that low testosterone levels may be a risk factor for cognitive decline and possibly for Alzheimer’s-type dementia, as well.1,2
Computer artwork of a molecule of the male sex hormone testosterone. The age-related decline in testosterone can result in a number of disturbing symptoms including reduced libido, stamina, muscle mass, and cognitive function, as well as making men increasingly prone to BPH and prostate cancer.
Testosterone occurs in two distinct forms in the body: free and bound. Free testosterone is useful and functional; bound testosterone is less so. Ironically, as a man’s production of testosterone declines, the amounts of a substance known as sex hormone-binding globulin (SHBG) often increase.3,4 Thus, remaining testosterone is increasingly bound by this protein, rendering already dwindling supplies less effectual. When assessing a man’s hormone status, clinicians frequently measure “total testosterone,” which includes free testosterone and testosterone bound to SHBG. It is free testosterone, however, that is the most relevant measure of a man’s testosterone status.5
Often called “testosterone deficiency syndrome,” male andropause is characterized by declining levels of free testosterone. Just as women undergo dramatic changes during menopause, men are now believed to suffer similar changes related to the age-associated decline in sex hormones, although these changes are more gradual, and perhaps less dramatic in men. “Consequences of testosterone deficiency syndrome…include depression, sexual dysfunction, mild cognitive impairment, osteoporosis, cardiovascular disease, and mortality,” Italian researchers wrote recently. “The consequences that are likely to impact on patients’ quality of life include sexual function, energy levels, body composition, mood, and cognitive function.”6 UCLA-based scientists noted, “manifestations of testosterone deficiency have included depression, anxiety, irritability, insomnia, weakness, diminished libido, impotence, poor memory, [and] reduced muscle and bone mass…”7
Just as free testosterone levels are declining with age, another detrimental process is taking place. Levels of the enzyme aromatase tend to increase with age (and increasing belly fat mass). Aromatase converts testosterone to estrogen, further depleting free testosterone levels and increasing estrogen levels. As a result, men become even more susceptible to complaints related to diminished testosterone levels, while becoming more prone to suffer the adverse effects of too much estrogen, which can include prostate enlargement and even increased risk for prostate cancer.8
Botanical Support for Male Virility
Recent insights into reversing the effects of male aging and preserving prostate health have led to new strategies for extending virility and youthfulness. It is possible to boost the availability of beneficial free testosterone and offset detrimental increases in estrogen using botanical extracts. This integrative approach to male aging may dramatically improve conditions ranging from flagging energy levels to fading libidos while simultaneously decreasing the chances that a man will fall victim to prostate enlargement or cancer.
Botanicals of interest include the Amazonian “nerve tonic” muira puama, which has been shown to possess antioxidant and antidepressant activities while benefiting male sexual function; the Peruvian “aphrodisiac,” maca, which has been shown to increase libido in cases of sexual dysfunction; the aromatase inhibitor chrysin (which may increase free testosterone, while decreasing potentially carcinogenic estradiol); the antioxidant/anti-inflammatory botanicals ginger and nettle, which may relieve the symptoms of enlarged prostate; and natural plant lignans, which offer impressive aromatase-inhibiting and prostate cancer-prevention activity.9-31
Maca (Lepidium meyenii)
Maca has been used among indigenous people in the Andes region for centuries. Maca is a vegetable in the same family as broccoli. It is a reputed aphrodisiac and fertility enhancer. Research has shown there is sound scientific basis for this belief. Maca improves libido while enhancing sperm production and sperm motility, according to recent research. And it achieves this without affecting male sex hormone levels.18,32,33 In 2002, Peruvian researchers conducted a randomized, placebo-controlled, double-blind study on a small group of men aged 21-56 years. Results showed that maca improved subjective reports of male sexual desire versus placebo. Subjects consumed either 1,500 mg or 3,000 mg maca, or placebo, for three months. After eight weeks, improvements were noted in sexual desire among the subjects who consumed maca.33
In late 2008, investigators at Massachusetts General Hospital conducted a double-blind, randomized, parallel group study of two different doses of maca for the treatment of sexual dysfunction related to the use of the selective-serotonin reuptake inhibitor (SSRI) class of modern antidepressant drugs20 (such as Prozac®, Zoloft®, or Paxil®). SSRI-induced sexual dysfunction, in the form of severely depressed libido among women, and inability to achieve orgasm among men, is a common side effect of these antidepressants.
Male and female subjects receiving 3,000 mg maca per day experienced a significant improvement in a standardized score of sexual function, while subjects taking placebo did not. “Maca root may alleviate SSRI-induced sexual dysfunction,” concluded researchers, “and there may be a dose-related effect. Maca may also have a beneficial effect on libido.” Importantly, maca was well tolerated by all subjects.20
In addition to improving sexual desire,33 semen quantity, and sperm quality in human males,18 maca has also repeatedly been shown to reduce prostate enlargement among animals with experimentally induced prostate enlargement.16,34-36 In one experiment, maca reduced prostate enlargement as effectively as a common drug used in men for the treatment of benign prostatic hyperplasia (BPH).35
Interestingly, maca has also been shown to significantly improve glucose tolerance, antioxidant levels, and lipid profiles among rodents with a hereditary tendency to develop abnormally high blood triglyceride levels. Despite their genetically abnormal lipid profiles, rats given maca while consuming a sugar-rich diet experienced significant improvements in a number of parameters related to cardiovascular disease risk, including lower total cholesterol and low-density lipoprotein (LDL) levels, and increased levels of the potent natural antioxidants, glutathione, superoxide dismutase, and glutathione peroxidase. “Results demonstrate that maca seems to be promising for a positive influence on chronic human diseases (characterized by atherogenous lipoprotein profile, aggravated antioxidative status, and impaired glucose tolerance), and their prevention,” researchers concluded.37
Muira puama (Ptychopetalum olacoides)
Depression, anxiety, and irritability are common side effects of age-induced testosterone deficiency. Muira puama has long been used by Amazonian people to manage various age-related conditions and support the body’s response to stress, and modern research shows that this reputation is well deserved. A recent rodent study conducted by Brazilian researchers showed that muira puama and the standard antidepressant drug, imipramine, were equally effective at alleviating symptoms of chronic mild stress-induced depression.9 Muira puama is marketed in Brazil as a “body stimulant, energetic, tonic, and aphrodisiac,” in combination with several other herbal extracts, including ginger and guarana (a source of caffeine).38 Research on human volunteers demonstrated that this cocktail of ingredients was safe and well tolerated. “No severe adverse reactions or haematological and biochemical changes were reported,” researchers concluded.
Muira puama is reputed to enhance erectile function and orgasm in aging men suffering the effects of fatigue or age-related complaints.31 In one study of 262 men suffering from poor sexual desire, more than 60% reported improvements with muira puama. Additionally, more than 50% of the men reported that muira puama improved their ability to attain an erection.39 While muira puama’s mechanism of action remains unknown, it is interesting to note that the plant contains sterols—the building blocks of sex hormones such as testosterone.
Muira puama may also alleviate age-related cognitive complaints. A notable experiment showed that muira puama alone “facilitates memory retrieval” in adult and aging mice. “Indeed, aging mice treated with [muira puama extract] performed as well as adult mice,” researchers concluded.40 Researchers have subsequently replicated these findings.41 At least one research team has proposed that muira puama acts as an acetylcholinesterase inhibitor. Acetylcholine is an important neurotransmitter involved in memory and cognition. One of the hallmarks of Alzheimer’s disease is a gradual decline in acetylcholine levels and the receptors for this neurotransmitter, especially in the hippocampus region of the brain. Although there is currently no cure for the disease, modern drugs to combat its progression include acetylcholinesterase inhibitors such as Aricept® (donepezil), which block the activity of an enzyme that breaks acetylcholine down.
In test tube experiments on rat brain tissue, scientists showed that muira puama extract “significantly inhibited [acetylcholinesterase] activity,” prompting the researchers to conclude, “we propose that such [acetylcholinesterase] inhibitory activity is a neurochemical correlate of a number of therapeutic properties traditionally claimed for [muira puama], particularly those associated with cognition.”42
Chrysin is a natural flavone found in numerous plants, but especially in passionflower (Passiflora incarnata). Research suggests that chrysin reduces anxiety by binding with receptors in the brain that are also targeted by anxiety-reducing drugs known as benzodiazepines (such as Xanax® or Valium®).25 In one study, chrysin’s anxiety-reducing effect was roughly comparable to that of a reference benzodiazepine drug.25 Recent research on rats demonstrates that chrysin may also promote healthy natural killer cell activity, which could minimize the metastatic spread of cancer.24 But chrysin’s primary benefit to human sexuality may derive from its ability to block aromatization.43
Aromatization is a chemical transformation that takes place in the body, whereby testosterone or other androgen hormones are converted to estrogens by the aromatase enzyme. Aromatase inhibitors are beneficial because they prevent the loss of free testosterone and the buildup of potentially dangerous estrogens. Synthetic aromatase inhibitors have quickly gained in popularity for the treatment of estrogen receptor-positive breast cancer, for instance, since the growth of these tumors is driven by estrogens.44,45
But men may also benefit from aromatase inhibition. A recent controlled clinical trial of the synthetic aromatase inhibitor, anastrozole, for the treatment of hypogonadism in aging men showed, “anastrozole administration normalized androgen production in older hypogonadal men and decreased estradiol production modestly.” There were no changes in lipid levels, prostate-specific antigen (PSA) levels, or red blood cell levels in this one-year study.46
These findings echo results reported earlier by the same team at Massachusetts General Hospital. Working with anastrozole, the scientists concluded, “these data demonstrate that aromatase inhibition increases serum bioavailable and total testosterone levels to the youthful normal range in older men with mild hypogonadism. Serum estradiol levels decrease modestly but remain within the normal male range.”47
Although chrysin has low oral bioavailability,48 its bioavailability may be significantly enhanced by co-administration with the pepper extract, piperine.49 The combination of chrysin with piperine may thus represent an important botanical strategy to optimize free testosterone levels and minimize excess estrogen levels by blocking aromatization.