Mucuna pruriens (cow-itch) also known as Velvet Bean is just one of the ingredients in Onnit’s T-Plus supplement that contains high concentrations of L-DOPA which is a precursor to the neurotransmitter dopamine.  This botanical also contains bioactive alkaloids mucunine, mucunadine, mucuadinine, pruriendine, nicotine, Beta-sitosterol, glutathione, lecithin, oils, yenolic and gallic acids.  It has been used as a carminative (relieves flatulence), hypertensive agent, hyperglycemic agent, anti-infertility agent, and has the ability to lower cholesterol.

L-DOPA is an amino acid that can be converted into dopamine.  Dopamine is an important neurotransmitter involved with locomotion, reward, and punishment.  Deficiencies cause your muscle to become tense and tremble.  Dopamine production starts with the amino acid tyrosine which gets converted into L-DOPA which in turn is converted into dopamine. 

Dopamine is reported to promote deep sleep, reduced body fat, improve skin texture, increase bone density and muscle mass, enhance libido and sexual performance, increase energy levels, elevate mood, lower cholesterol, and strengthen the immune system.

L-DOPA boosts growth hormone, converts to dopamine, inhibits prolactin, stimulates luteinizing hormone which increases testosterone production, and regulates stAR (steroidalgenic acute regulatory protein) which is responsible for transporting cholesterol from the cytosolic space into the mitochondria.  There are a number of stARs.  One such stAR carries cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane and there are those that transport cholesterol in the cytoplasmic space to where ever it needs to go.  The stAR regulatory proteins are the rate limiting step for making testosterone from cholesterol.  Dopamine made from L-DOPA inhibits the production of prolactin which in turn allows testosterone to be made.  These pathways are peculiar to the adrenal glands, testes and ovaries.  No doubt, Mucuna may be an excellent testo booster.

L-DOPA promotes the release of growth hormone.  When converted to dopamine, this increases human growth hormone (GH) production in the pituitary gland.  GH is released into the blood and circulates to the testes were it binds to cell surface receptors and activates an internal pathway the initates the production of testosterone.  The release of testosterone from the testes stimulates muscle growth and fat catabolism in adipose tissue.  The testosterone that remain behind is used for spermatogenesis.  The L-DOPA in Mucuna packs a double punch as a testo booster by stimulating GH and inhibiting prolactin (PR).

Animal and Human Studies

Animal studies indicate that Mucuna increases sperm count.  The molecules purienine and purienidine were found to increase secretion of testosterone making more available to the testes which leads to an increased sperm count (spermiogenesis) as well as an increase testes size.

Human growth hormone is an anabolic agent known to burn fat and increase lean muscle mass.  Although it is not effective nor safe to take growth hormone, L-DOPA is.  L-DOPA increases the production and release of growth hormone effectively increasing blood serum levels. 

Mucuna has also been shown to increase testosterone levels and spermtogenesis both in animal and human studies by way of prolactin inhibition.  This hormone is known to suppress male testosterone production.  L-DOPA inhibits prolactin production thereby allowing testosterone to be made. 

Studies done at C.S.M. Medical University in Lucknow, India have elucidated the mechanism of action of Mucuna in male patients who were infertile.  Seventy-five male patients who where infertile were compared to 75 healthy fertile men.  Before and after treatment, serum testosterone, luteinizing hormone, follicle stimulating hormone, prolactin, dopamine, adrenaline, and noradrenaline in seminal fluid and blood plasma were measured. 

Before administration of Mucuna, infertile men had decreased sperm counts and motility.  Testosterone, dopamine, adrenaline, noradrenaline, and luteinizing hormone (LH) serum levels were low as well as seminal levels of dopamine, adrenaline, and noradrenaline.  Treatment with Mucuna significantly increased testosterone, LH, dopamine, adrenaline, and noradrenaline levels while reducing their levels of follicle stimulating hormone (FSH) and prolactin (PRL).  This group of researchers concluded that Mucuna treatment regulates steroidogenesis while improving semen quality in infertile men.  

A rat study administered ethinyl estradiol to generate a rat model that had compromised spermatogenesis (down-regulated the endocrine axis).  Mucuna was administered to see if they could get recovery.  Sperm counts and motility, testis architecture, reactive oxygen species (ROS), mitochondrial membrane potential, apoptosis, peripheral hormone levels, and testicular germ cell populations were analyzed.  It was observed that Mucuna regulated ROS levels, apoptosis (programed cell death), mitochondrial membrane potential and was able to restore the hypothalamic-pituitary-gonadal axis leading to an increased sperm count and motility. 

Ethinyl estradiol is known to generate an imbalance between cell proliferation and cell death, along with hormonal disruption (decreased hormonal levels) in cell culture.  Increases in ROS were observed, sperm maturation failure and depletion of serum testosterone.  In fact, the whole hypothalamic-pituitary-gonadal endocrine axis was suppressed.  The rise in reactive oxygen species (ROS) increased sperm cell death along with a decrease in mitochondrial membrane potential.  This group of researchers remarked that the physiological abnormalities they observed with ethinyl estradiol administration matched the disturbances seen in infertile human individuals suggesting that this was a reasonable animal model to extrapolate to the human pathways.

Furthermore,  research over the past decade has been able to demonstrate that oxidative stress is a major factor in male infertility.  It has also been suggested that deficiencies in various cofactors (B vitamins) and essential minerals (magnesium, zinc, etc) add insult to injury.

This group of researchers found that the major effect of Mucuna on spermatogenesis came by way of restoration of the endocrine axis that had been suppressed by ethinyl estradiol administration. 

One needs to consider there are a number of environmental estrogens that are capable of mimicking estradiol that we are exposed to everyday.  These include prescription drugs, supplements, industrial products, agriculture, and materials in our homes.  Exposure could severely damage spermatogenesis in the adult male but could also affect a developing fetus with serious consequences showing up in the neonate and beyond.  Given the results of this study, Mucuna may be able to reverse the averse affects of environmental exposure to estrogens.  Mucuna could be used as a protective health supplement maintaining a healthy reproductive system.    

The presence of L-DOPA in Mucuna accounts for the majority of its overall health benefits however, it contains a mixture of alkaloids, nutrients, antioxidants, and adaptogens that act in a synergistic way.  These researchers suggest that their studies on animals and humans demonstrate that Mucuna improves spermatogenesis by recovery of the endocrine axis and testicular homeostasis which leads to better semen quality.

Looking for a healthy dose of Mucuna to boost testosterone levels?  Consider Onnit’s T-Plus.  It contains 3 different proprietary blends to enhance testosterone levels and adds estrogen blockers to ensure testosterone levels remain high.  This product is meant to build lean muscle, burn fat, and prevent feminization.


Mucuna pruriens contains L-DOPA and a number of bioactive alkaloids and antioxidants.  Research has demonstrated that Mucuna has the ability to raise dopamine levels, luteinizing hormone, and growth hormone and in turn raise testosterone levels.  It also has the ability to inhibit the production of prolactin which allows for even greater production of testosterone.  Powerful antioxidants have the ability to repair mitochondrial damage due to reactive oxygen species accumulation.  Mucuna has been suggested to be able to restore an abnormal endocrine axis bringing back health testosterone levels and spermatogenesis.  Onnit’s T-Plus includes Mucuna to raise testosterone levels to help boost lean muscle mass and inhibit free radical production.

Resource List:

Mucuna pruriens improves male fertility by its action on the hypothalamus-pituitary-gonadal axis.

Nikolaeva AA, Koroleva SV, Ashmarin IP. [Research of interactions in the dopamine-serotonin-somatostatin system promises new outlook in fundamental and practical respects] Nikolaeva AA, Koroleva SV, Ashmarin IP. Eksp Klin Farmakol. 2009 Mar-Apr;72(2):60-4. Review

Cordido F, Isidro ML, Nemiña R, Sangiao-Alvarellos S.Ghrelin and growth hormone secretagogues, physiological and pharmacological aspect. Curr Drug Discov Technol. 2009 Mar;6(1):34-42.

Mucuna pruriens and Its Major Constituent L-DOPA Recover Spermatogenic Loss by Combating ROS, Loss of Mitochondrial Membrane Potential and Apoptosis

Chaki SP, Misro MM, Gautam DK, Kaushik M, Ghosh D, et al. (2006) Estradiol treatment induces testicular oxidative stress and germ cell apoptosis in rats. Apoptosis 11: 1427–1437. doi: 10.1007/s10495-006-8761-4Find this article online

Agarwal A, Makker K, Sharma R (2008) Clinical relevance of oxidative stress in male factor infertility: an update. Am J Reprod Immunol 59: 2–11. doi: 10.1111/j.1600-0897.2007.00559.xFind this article online

Agarwal A, Said TM (2005) Oxidative stress, DNA damage and apoptosis in male infertility: a clinical approach. BJU Int 95: 503–507. doi: 10.1111/j.1464-410X.2005.05328.xFind this article online

Gulcin I (2007) Comparison of in vitro antioxidant and antiradical activities of L-tyrosine and L-Dopa. Amino Acids 32: 431–438. doi: 10.1007/s00726-006-0379-xFind this article online

The Molecular Biology, Biochemistry, and Physiology of Human Steroidogenesis and Its Disorders