What causes a man's testosterone to be low?
Low testosterone is not limited to one cause. Aging, environmental stressors, and injury to the testicles can disrupt testosterone production. As men age, their ability to produce/maintain adequate testosterone levels diminishes. Secretion of hormones that further spur the testosterone-producing capacities of the testicles are affected by this diminished activity.
Environmental stressors can further disrupt production. Preservative-rich food can interfere with this process. Food products containing soy can actually raise estrogen levels. Males with elevated estrogen levels typically have increased belly fat and less lean muscle composition. Furthermore, increased estrogen levels can attribute to erectile dysfunction and loss of sexual interest. Research has even shown that some plastics containing food-products can further disrupt testosterone production; such as BPA - a biochemical utilized in some plastics production.
The stress of life can negatively impact testosterone production. Increased stress is directly related to increased cortisol levels. Cortisol is a hormone associated with inflammation and immune responses. But elevated cortisol levels over a sustained period of time can hamper testosterone production.