Based on our testing and research, TestoGen works for many but not all men. Many TestoGen users report that the supplement has been very effective in encouraging testosterone production in their bodies, and it’s a generally quite safe alternative for people who don’t want to engage in full hormone-replacement therapy (HRT). Our testing suggests that consistency is crucial for seeing the gains you’re looking for, in addition to patience; this isn’t an overnight transformation. Animal studies confirm that D-aspartic acid raises testosterone levels. Clinical trials on humans are still somewhat lacking for d-aspartic acid, with some studies indicating clear increase in testosterone and others showing a lack of effect.