Melatonin
Researchers at Hamek Medical Centre in Israel performed a six month,
double-blind, placebo-controlled study of a daily treatment dose
of three milligrams of melatonin in eight men.
The men consumed the melatonin or placebo orally at 6pm. Semen
quality (concentration, motility and morphology), serum and seminal
plasma 17-beta-estradiol (E(2), testosterone, melatonin and serum
gonadotropin levels were determined after three months and at the
end of the study.
In six men, there was no change in semen quality or in semen and
seminal plasma hormone levels.
On the other hand, during the melatonin treatment period, two men
experienced a significant drop in sperm concentration and motility
(32% and 30%, respectively).
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 one 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 eight men.
According to the authors, "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."
Reference
Luboshitzky R, Shen-Orr Z, Nave R, Lavi S, Lavie P. (2002). Melatonin
administration alters semen quality in healthy men. Journl
of Andrology, 23, 572-578
|