Acetyl-l-carnitine is a substance chemically corresponding to the acetyl ester of carnitine, a substance naturally present in animal tissues whose best known function is to transport fatty acids within the mitochondria, where they are converted into energy. There are several properties that are ascribed to acetyl-l-carnitine, thanks to which this substance is currently marketed and included as an ingredient in various supplements: it seems that it has antioxidant functions for the human body, and that in particular it performs a protective action on the brain. The cytoprotective action of Acetyl-L-Carnitine has proved effective in neurodegenerative diseases such as neuropathies, Alzheimer’s disease, Down syndrome and senile dementia. Among the other properties that would characterize it, there would also be the stimulation and release of various hormones, including testosterone.