Cruciferous vegetables like broccoli are rich in indoles, anti-cancer compounds that indirectly boost testosterone production by breaking down and flushing the system of excess estrogen, which inhibits the production of male sex hormones. As men age, their estrogen levels gradually rise, while testosterone levels fall. Indoles can help strike the balance. In one study, supplementing with indole-3-carbinol from cruciferous vegetables for just 7 days cut the estrogen hormone estradiol in half for men. Another study found indole supplementation significant increased urinary excretion of estrogens among men.
Vitamin D and zinc are both essential to testosterone production. A year-long study looked at the vitamin D and testosterone levels of 2299 men. It found that men with vitamin D levels above 30 nmol/L had more testosterone and lower levels of sex hormone-binding globulin (SHBG). SHBG binds to hormones so your cells can’t use them, and if you have too much of it, your testosterone levels drop . Men with vitamin D deficiency had lower testosterone and higher SHBG levels.
Although some men believe that taking testosterone medications may help them feel younger and more vigorous as they age, few rigorous studies have examined testosterone therapy in men who have healthy testosterone levels. And some small studies have revealed mixed results. For example, in one study healthy men who took testosterone medications increased muscle mass but didn't gain strength.