4 MEN’S HEALTH Manly Minerals When you think of minerals, sex is probably the last thing on your mind. But two minerals have proven themselves indispensable for healthy testosterone levels and sperm quality. Zinc is an essential mineral that’s involved in many bodily functions including testosterone production. A 1996 study showed a very clear relationship between zinc and testosterone levels. Young men were fed a diet deliberately low in zinc. After 20 weeks, blood testosterone levels were nearly 75 percent lower than at the start of the study. Fortunately, the study also examined zinc supplementation in elderly men. Researchers showed that increasing zinc intake almost doubled testosterone levels in the elderly population. Selenium is another essential trace mineral that is found in the testis. Because selenium is a powerful antioxidant, preliminary studies have found that it plays a protective role against reproductive toxicity in men.As a happy bonus, this mineral also increases the synthesis of testosterone. The Secret of L-citrulline Best known as a sports performance supplement, this amino acid is quickly gaining a reputation for its ability to improve a man’s performance in the bedroom as well. In one study that appeared in the journal Urology, 24 men with mild ED were given a placebo for one month followed by a daily dose of l-citrulline for another month. Half of the men reported that taking the supplement fully restored erectile function. What’s l-citrulline’s secret? Once consumed, it is converted into arginine—the amino acid that enhances blood flow by boosting nitric oxide. Another bonus? Taking l-citrulline increases arginine plasma levels over a considerably longer period of time than if you took a supplement containing only l-arginine. Maca is a Peruvian herb purported to boost endurance, stamina, and sexual virility. It’s also used by both men and women to stimulate both libido and pelvic blood flow. But does it work? A 12-week double-blind, placebo-controlled study found that healthy men who took the herb did indeed have an increase in desire. Earlier studies had found that maca also increases stamina. The key to maca’s effectiveness are glucosinolates, natural plant compounds that help balance hormone levels, particularly testosterone. Research in the journal Urology shows that glucosinolates help to decrease the amount of time it takes to achieve and maintain an erection. But what’s really astounding is that this same research also showed that the compound can boost libido by over 300 percent versus a placebo. For best results, seek out a supplement that provides a 4:1 extract of the maca root. Tribulus terrestris has been used throughout Europe to balance hormone levels and encourage longer-lasting erections. Preliminary research discovered that a proprietary tribulus compound extended the period of sexual activity thanks to elevated testosterone levels. Tribulus may increase testosterone levels indirectly by raising blood levels of luteinizing hormone (LH). LH is produced by the pituitary gland and plays a role in regulating natural testosterone production and serum levels by “turning on” natural testosterone production in humans. In two separate analyses of tribulus, Turkish and Korean researchers found that the herb also relaxes smooth muscle, allowing enhanced blood to flow into the penis. In addition, Bulgarian scientists found that tribulus increases the quality and quantity of sperm production, improves sperm motility, and helps ensure the sperm’s survival. Look for a 12:1 tribulus extract for optimal results.