Long term melatonin supplementation may decrease sperm quality in men

[Nelson Vergel]

Melatonin administration alters semen quality in healthy men. Luboshitzky R, et al.Journal J Androl. 2002 Jul-Aug;23(4):572-8.
Androl. 2004 Mar-Apr;25(2):185-6; author reply 186-7.

Abstract
The role of melatonin in the regulation of reproduction in humans is unknown. We conducted a 6-month, double-blind, crossover study of a daily treatment dose of 3 mg melatonin or placebo given orally at 1700 hours in 8 healthy men. Semen quality (concentration, motility, and morphology), serum and seminal plasma 17-beta-estradiol (E(2)), testosterone, melatonin, and serum gonadotropin levels were determined every 3 months throughout the study. In 6 men, there was no change in semen quality or in serum and seminal plasma hormone levels during the study period. In 2 men, during the melatonin treatment period, sperm concentration decreased to 3 x 10(6)/mL and 12 x 10(6)/mL, and motility declined to 32% and 30%. These coincided with a decline in seminal plasma and serum E(2) levels and with an increase in testosterone:E(2) ratios. Six months after the cessation of melatonin, sperm concentration and motility were normal in 1 man but remained abnormal in the other one with a still elevated testosterone:E(2) ratio. Serum gonadotropin levels were unchanged during the study in all 8 men. Our preliminary observations suggest that long-term melatonin administration is associated with decreased semen quality in a number of healthy men, probably through the inhibition of aromatase at the testicular level.

 

[Jeffrey Becker]

Well, 2 of 8 men were negatively affected whereas the other were not affected. And the melatonin was administered at 5pm, which seemingly would disrupt the circadian cycle.

 

[Nelson Vergel]

Highlights
· Melatonin regulates the secretion of two key neurohormones, GnRH and LH.
· Melatonin regulates testosterone synthesis and testicular maturation.
· Melatonin prevents testicular damage caused by environmental toxins or inflammation as a potent free radical scavenger.


Li C, Zhou X. Melatonin and male reproduction. Clin Chim Acta. http://www.sciencedirect.com/science/article/pii/S0009898115002284


Melatonin is a neurohormone secreted by the pineal gland whose concentrations in the body are regulated by both the dark-light and seasonal cycles. The reproductive function of seasonal breeding animals is clearly influenced by the circadian variation in melatonin levels. Moreover, a growing body of evidence indicates that melatonin has important effects in the reproduction of some non-seasonal breeding animals. In males, melatonin affects reproductive regulation in three main ways. First, it regulates the secretion of two key neurohormones, GnRH and LH. Second, it regulates testosterone synthesis and testicular maturation. Third, as a potent free radical scavenger that is both lipophilic and hydrophilic, it prevents testicular damage caused by environmental toxins or inflammation. This review summarizes the existing data on the possible biological roles of melatonin in male reproduction. Overall, the literature data indicate that melatonin affects the secretion of both gonadotropins and testosterone while also improving sperm quality. This implies that it has important effects on the regulation of testicular development and male reproduction.

 

[Dr. John Crisler]

I love melatonin.

....and it loves me.

 

[JPB]

It seems melatonin's influence on gonadotropins and LH, FSH remains unclear in humans, and in regards to dosage, and age. Some think melatonin levels, which are quite high in childhood, may be an inhibiting factor on sexual maturation. Others point to seasonal variations in hormone levels, with T levels noted to increase in the late summer early fall (subsequent to a period of lower melatonin output from longer daylight hours). With aging melatonin levels typically fall off, as do gonadotropin levels.

Unfortunately the full articles usually require paying if you do not have access otherwise.


Melatonin and human reproduction: shedding light on the darkness hormone.

Srinivasan V1, Spence WD, Pandi-Perumal SR, Zakharia R, Bhatnagar KP, Brzezinski A.
Author information



Abstract

Melatonin, N-acetyl-5-methoxytryptamine, is a molecule with diverse physiological functions. This neuro-hormone affects reproductive performance in a wide variety of species. In most animals, but not exclusively all, melatonin has an antigonadotrophic effect. The seasonal changes in the number of hours per day that melatonin is secreted mediate the temporal coupling of reproductive activity to seasonal changes in day-length. These observations stimulated a search for a role for the pineal gland and melatonin in human reproduction. Clinical experience related to this issue has yielded inconclusive and sometimes conflicting results. This article reviews the current available evidence concerning the effects of melatonin on human reproductive processes (e.g., puberty, ovulation, pregnancy, and fertility). Possible reasons for the vagueness and elusiveness of the clinical effects are discussed.

 

[Dr. John Crisler]

Once we have seized control of the endocrine system, it doesn't matter.

 

[JPB]

Well I get your point but I'm not sure you get mine. If one is trying to stimulate their systems with Clomid, and they are taking big dosages of Melatonin, there is a possibility it could hinder this. With Melatonin there is not much hard data to guide its use. Yes it is probably very safe, but its interactions with the reproductive systems are complex and not fully sorted out.

With TRT you shutdown natural systems via replacement, certainly logical when identifying deficits in natural output. I suppose you could consider that seizing control, but in regards to measurement and tracking of target levels such is not really viable with Melatonin. But a good night's sleep is desirable and that is the reason most people take it. Dosing is really based solely on subjective response. 10 years ago it was rather uncommon to see people taking dosage upward of 10mg, now its becoming more common. Its also being used more with children.

I'm going to try to be more conservative with my own use of it, until there is more data.

 

[Dr. John Crisler]

The multitude and magnitude of the various negative influences which downgrade endogenous testosterone production may never be known. From the lectures I have attended by Dr. Reiter, re-establishing circadian rythm--and getting proper sleep--trumps all.

The simple and most basic fact is (1) we are ALL quite deficient in melatonin, and (2) we really need melatonin to be healthy.

Yes, administering TRT is definitely seizing control of the HPTA (and very much influencing many other systems as well). That is how we should always look at it.

Dr. Reiter has published over 1,200 papers on melatonin. We indeed know a lot about it. Unfortunately, most of what people think they know is BroScience i.e that melatonin inhibits its own production.

IF it turns out to be true melatonin is also an aromatase inhibitor, all the better.

 

[Nelson Vergel]

(305) Impact of Melatonin Supplementation on Testosterone Levels in U.S. Adult Men

AbstractIntroduction. Among US adults, the prevalence of melatonin supplement consumption significantly increased in the last two decades across all demogr

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