Testosterone is observed in most vertebrates. Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes (jawed vertebrates).[193] Agnathans (jawless vertebrates) such as lampreys do not produce testosterone but instead use androstenedione as a male sex hormone.[194] Fish make a slightly different form called 11-ketotestosterone.[195] Its counterpart in insects is ecdysone.[196] The presence of these ubiquitous steroids in a wide range of animals suggest that sex hormones have an ancient evolutionary history.[197]
^ Butenandt A, Hanisch G (1935). "Umwandlung des Dehydroandrosterons in Androstendiol und Testosterone; ein Weg zur Darstellung des Testosterons aus Cholestrin" [About Testosterone. Conversion of Dehydro-androsterons into androstendiol and testosterone; a way for the structure assignment of testosterone from cholesterol]. Hoppe-Seyler's Z Physiol Chem (in German). 237 (2): 89–97. doi:10.1515/bchm2.1935.237.1-3.89.
In many of the studies we found, those who saw the most improvement in health, testosterone, or muscle gain were those with existing nutrient or vitamin deficiencies. This means that some gains may be due more to dietary changes and generally restoring nutrient and vitamin levels than any one magic ingredient, but also that making sure your diet includes healthy amounts of nutrients should be your first step.
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Testosterone, historically believed to be important only for male sexual function, has over the past decades transformed from niche hormone to multi-system player.22 There is increasing recognition of the harmful consequences of hypogonadism (also known as testosterone deficiency) wide spectrum of beneficial health effects of testosterone therapy and.23, 24
Testosterone levels generally peak during adolescence and early adulthood. As you get older, your testosterone level gradually declines — typically about 1 percent a year after age 30 or 40. It is important to determine in older men if a low testosterone level is simply due to the decline of normal aging or if it is due to a disease (hypogonadism).
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