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-diol or 4AD (4-androsten-3,17-diol)
Target Hormone: Testosterone
Molecular name of target hormone: 4-androstene-3-one,17ß-ol
Target conversion: High (15.76 %)
Conversion enzyme: 3-ß-hydroxysteroid dehydrogenase (3HSD)
DHT conversion: low, only from target hormone
Estrogenic effects: no aromatisation from compound, some from target hormone
According to many, this is the very best prohormones have to offer, but I beg to differ. Nonetheless my second choice. Because it's a diol it has no aromatisation prior to conversion, significantly lessening the risk of excessive estrogenic formation. It also doesn't make a direct conversion to DHT. Its structurally incapable of doing so. DHT is still a risk, because of the higher amount of testosterine produced and the fact that testosterine (through 5-alpha-reducates) can be converted to DHT in the Sertoli cells. This makes this a definite winner. If it doesn't give you results due to bad conversion, it also won't give you the side effects, because basically if it doesn't convert it can't make estrogens or DHT. That only makes the risk increase with the gains, and makes 4AD one of the safer prohormones.
4-diol is also by far the most anabolic of the three testosterone prohormones, offering almost three times as much conversion as andro and over 20 times higher than DHEA or 5-diol. In the real world that translates to 310% greater increase in testosterone and 256% greater increase in free testosterone (available) than andro (based on results compared to a control group) and 129% more anabolic than 5-diol¹
For testosterone conversion and pure legal anabolic, androgenic action, nothing beats 4-diol at this point. Especially once you pass 30 and your test levels begin to taper, the effects of 4-diol will exert a major effect on both gains and strength. 4-diol, after all, also seems to have a strong pre-workout energizing effect and a positive influence on libido.
¹ Ristovic L.J., Cobanovic M., Kem Ind, 24(7), 389-92