Which hormones can affect male libido?

For some men, decreased levels of testosterone may be to blame for a flagging libido. This hormone helps maintain sex drive and sperm production, as well as muscle mass, bone density, and red-blood-cell production. Testosterone peaks in adolescence and early adulthood and naturally declines with age. It's also greatly affected by lifestyle factors: Exercise boosts testosterone, while chronic stress depletes it. Depending on your guy's age, he may want to ask his doctor for a blood test to check his testosterone levels. Supplemental testosterone can help boost libido in men who are deficient but needs be prescribed carefully, since high amounts can inhibit a man's natural production of testosterone.

Adequate levels of the brain chemical dopamine are necessary for sexual desire. There's some evidence that dopamine-boosting medications used to treat Parkinson's disease may also increase sex drive in men. On the other hand, too much dopamine can cause psychosis. It's all about balance. Foods that are rich in tyrosine (building block of dopamine), such as avocados, pumpkin seeds, bananas, and dairy products, can help boost levels, while sugar and refined foods tend to deplete levels of dopamine in the brain.