Z-Core PM Review

Z-Core PM is a sleep-aid designed to support healthy testosterone levels at rest. As a sleep-aid it may be moderately effective, due primarily to the inclusion of Melatonin. As a testosterone optimizer, its iffy…

MusclePharm Z-Core PM



Zinc is an essential trace mineral that is required for a wide range of bodily functions, the most well-documented of which is its role in immune function. Several studies have demonstrated the ability of zinc to shorten cold symptoms. Zinc has also been studied for its possible role in testosterone production.

A 2005 study noted that men with fertility issues stemming from low testosterone also had low plasma zinc levels. While these findings certainly cannot be considered conclusive in any way, they do suggest that zinc is linked to testosterone in some way. However, the overall consensus among medical professionals seems to be that there is not enough evidence to support these claims and just because a correlation exists, does not mean that more zinc equals more testosterone.

People who eat a diet with plenty of meats and seafood (especially shellfish) receive enough dietary zinc to fulfill all physiological needs. If you are considering buying this product, you probably already eat plenty of these foods for protein, and thus, you are most likely NOT zinc deficient.


Magnesium is the fourth most abundant element in the human body, with about half being found in bone and the other half being found in various cells throughout the body. It is essential maintaining normal muscle and nerve function, keeping a steady heart rhythm, supporting a healthy immune system, and maintain optimal bone health. Claims have been made that magnesium deficiency may result in trouble sleeping, and given that magnesium is required for proper nerve/muscle relaxation, so it is quite possible that a severe deficiency would disrupt sleep quality. However, no study has proved that magnesium supplementation in individuals with no deficiency can increase sleep quality


ZMA is a combination of zinc, magnesium, and Vitamin B6, which has gained a lot of popularity as a testosterone enhancing sleep supplement. Muscle Pharm claims that Z-core PM: “Supports Natural Testosterone Levels, Muscle Strength And Recovery!”, but is this claim substantiated by any scientific evidence?

A 2004, placebo-controlled, double-blind study, published in the Journal of the International Society of Sports Nutrition, found that 8 weeks of ZMA supplementation before bed failed to have an effect on the anabolic/catabolic hormone profile of resistance-trained males. In 2006, a European study found that ZMA supplementation had no effect on serum testosterone levels or testosterone metabolite levels in urine. These results indicate the same as the previous study, which is that ZMA DOES NOT increase testosterone.

So where do these claims come from? It seems the only study that has ever “proved” the efficacy of ZMA supplements is a study conducted by SNAC Systems, the company responsible for the original ZMA, and owner of the ZMA trademark. As if the conflict of interest here wasn’t obvious enough, a co-author of the study, Victor Conte, holds a significant amount of equity in SNAC. The study was carried out in a Bay Area Laboratory Co-operative (BALCO) research facility which Victor Conte helped found. Due to the massive conflict of interest, we have no choice but to disregard this study and, without it, the claims that ZMA increases testosterone are entirely lacking any factual basis.


Trigonella Foenum Greacum (A.K.A. Fenugreek) is an herbal extract that has gained traction in the supplement industry as a libido enhancer. However, a 2009 study, published in the International Journal of Exercise Science, found that males who supplemented with fenugreek extract showed no increase in anabolic hormones. This study was supported by Indus Biotech, a company that manufactures fenugreek as an aromatase inhibitor.

Furthermore, a 2011 double-blind, placebo controlled study found that 6 weeks of supplementation with a Fenugreek derived supplement (Testofen) led to scoring 25% higher on a libido test (sexual arousal and orgasm in particular) than the placebo group. However, for the purpose of this analysis, it’s worth noting that “serum prolactin and testosterone levels remained within the reference range”, meaning that the mechanism of action was not an increase in testosterone. So if these studies have concluded that Fenugreek does not result in a significant increase in testosterone, then how has this supplement gained traction?

Well, one 2010 study, published in International Journal of Sports Nutrition, found that supplementation with 500 mg of fenugreek extract resulted in a significant increase in free-testosterone levels. While the results of this study seem to support the claims made by various supplement companies who sell fenugreek supplements, it’s worth mentioning that this study has a bit of a conflict of interest. It was funded by Indus Biotech, the above mentioned company that manufactures fenugreek extract, and supplied the extract used in this study. Now, most studies on supplements are funded by supplement companies, so we can’t rule this study out just because it was too, but given that the results of this study conflict with the results of the earlier (2009) study funded by the same company, so it does pose the question: what changed between the two studies?


Melatonin is a hormone secreted by the pineal gland, found in the brain. Melatonin is heavily involved in the sleep-wake cycle (by causing drowsiness when secreted), as well as possessing antioxidant properties. Due to its role in promoting sleep, supplemental melatonin has been used to correct to treat mild sleep disorders, as well as by people who wish to achieve deeper, sounder sleep. All evidence suggests that melatonin works very well when it comes to promoting and enhancing sleep.

However, the effects on melatonin supplementation on testosterone production are much more unclear. A 2001 study in the Journal of Clinical Endocrinology & Metabolism found that testosterone production was significantly hindered when sleeping subjects were unable to enter first REM sleep. These findings indicate that “sleep-related rise in serum testosterone levels is linked with the appearance of first REM sleep”.

A 2004 study, also published in the Journal of Clinical Endocrinology & Metabolism, found that melatonin significantly increased REM sleep in subjects who suffer from lower than normal REM sleep durations. Several other studies have demonstrated the ability of melatonin to increase REM sleep duration. Therefore, it is possible that melatonin increases testosterone production via increasing REM sleep.

However, studies that directly compare the effects of melatonin administration on testosterone production are lacking, and it is possible that there is a limit on the amount of testosterone produced during REM. In other words, more REM does not necessarily translate to more testosterone production. However, people suffering from REM deprivation may benefit greatly from melatonin supplementation. As far as the dose, melatonin has been demonstrated to be very effective at inducing sleep at 3mg which is the dosage that Z-core contains.


Z-Core PM is not likely to have much of an impact on Testosterone levels accept in those who are Zinc/Magnesium deficient.  Due to the melatonin content in Z-core PM, users may experience deeper sleep, but it is doubtful that anyone using this product would experience increased testosterone levels. The same restful sleep could be achieved by using a simple OTC melatonin supplement purchased for $5-$10.

[expand title=”REFERENCES” tag=”h5″]

  1. Wilborn, Colin D., et al. “Effects of zinc magnesium aspartate (ZMA) supplementation on training adaptations and markers of anabolism and catabolism.” J Int Soc Sports Nutr 1.2 (2004): 12-20.
  2. Prasad, Ananda S., et al. “Zinc status and serum testosterone levels of healthy adults.” Nutrition 12.5 (1996): 344-348.
  3. Koehler, K., et al. “Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement.”European journal of clinical nutrition 63.1 (2007): 65-70.
  4. Rondanelli, Mariangela, et al. “The Effect of Melatonin, Magnesium, and Zinc on Primary Insomnia in Long‐Term Care Facility Residents in Italy: A Double‐Blind, Placebo‐Controlled Clinical Trial.” Journal of the American Geriatrics Society59.1 (2011): 82-90.
  5. Netter, A., K. Nahoul, and R. Hartoma. “Effect of zinc administration on plasma testosterone, dihydrotestosterone, and sperm count.” Systems Biology in Reproductive Medicine 7.1 (1981): 69-73.
  6. Ali, Hasan, et al. “Relationship of serum and seminal plasma zinc levels and serum testosterone in oligospermic and azoospermic infertile men.” Journal of the College of Physicians and Surgeons–Pakistan: JCPSP 15.11 (2005): 671-673.
  7. “Zinc.” — Health Professional Fact Sheet. N.p., n.d. Web. 11 July 2013. .
  8. “Magnesium.” — Health Professional Fact Sheet. N.p., n.d. Web. 11 July 2013. .
  9. Steels, Elizabeth, Amanda Rao, and Luis Vitetta. “Physiological Aspects of Male Libido Enhanced by Standardized Trigonella foenum‐graecum Extract and Mineral Formulation.” Phytotherapy Research 25.9 (2011): 1294-1300.
  10. Bushey, Brandon, et al. “Fenugreek Extract Supplementation Has No effect on the Hormonal Profile of Resitance-Trained Males.” International Journal of Exercise Science: Conference Abstract Submissions. Vol. 2. No. 1. 2009.
  11. Wilborn, Colin, et al. “Effects of a Purported Aromatase and 5 α-Reductase Inhibitor on Hormone Profiles in College-Age Men.” International journal of sport nutrition 20.6 (2010): 457.
  12. Luboshitzky, Rafael, et al. “Disruption of the nocturnal testosterone rhythm by sleep fragmentation in normal men.” Journal of Clinical Endocrinology & Metabolism 86.3 (2001): 1134-1139.
  13. Kunz, Dieter, et al. “Melatonin in patients with reduced REM sleep duration: two randomized controlled trials.” Journal of Clinical Endocrinology & Metabolism 89.1 (2004): 128-134.
  14. Brzezinski, Amnon, et al. “Effects of exogenous melatonin on sleep: a meta-analysis.” Sleep medicine reviews 9.1 (2005): 41-50.
  15. Cajochen, Christian, et al. “Melatonin and S-20098 increase REM sleep and wake-up propensity without modifying NREM sleep homeostasis.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 272.4 (1997): R1189-R1196.

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