The main active ingredient in most of the commercially available natural testosterone boosters is Tribulus. Tribulus is derived from a plant, and when it is taken for extended periods, it is known to enhance testosterone production. The amino acid D-Aspartic Acid is gaining popularity as a testosterone booster because it has been shown to enhance testosterone production. Some people may confuse natural testosterone boosters with prohormones or steroids, and most of the disparaging media coverage of supplements is linked to prohormones. Unlike natural testosterone boosters, prohormones are metabolized into anabolic steroids inside the body. The FDA is the process of reviewing the supplements that are currently on the market and they have begun to ban those that are considered prohormones.