Testosterone is produced by the pituitary gland and in many cases, it is not known whether testosterone is a good supplement or a bad supplement. A medical doctor specializing in testosterone, however, can review the evidence and advise you to take a product that is best for your needs. Here are some of the best testosterone supplements out there. 1. Testosterone Gels The most common testosterone supplements are gel testosterone products. Gel testosterone products come in a wide variety of colors, but you can't have a good product if the color doesn't match the color of your skin. A gel testosterone product is made up of several substances. The first ingredient is the testosterone molecule. The other ingredients are often a form of an amino acid that has been chemically altered in order to make the gel an effective testosterone treatment. The other common ingredients in a gel testosterone product are calcium carbonate (a white powder) and magnesium stearate (a white powder). The calcium carbonate is typically used as a thickening agent, and it adds stability to the gel product. The magnesium stearate is used to add lightness and to reduce the gel to a soft gel. The gel may look like a natural gel, but in fact, it is the result of a process called electrolysis (which is done to separate the fatty acids from the water). The gel is then mixed with water to form a liquid.