What are the causes of impotence, depression and fatigue in four million American men? Natural supplements are an alternative to creams gels patches. Dietary changes take longer but have fewer side effects. After 40, testosterone and DHEA (a precursor hormone to testosterone) begin to decline in men. The peak age for testosterone production is actually 17 years old. After that, it slowly declines over the course of your entire life. It is not noticeable until you are 40+. A simple…