"Age is just a number. But for men that number says a lot about whats going on in their bodies. Starting at about age  men start producing less testosterone the hormone that helps spark sex drive build muscle and stoke energy ambition and aggression. In short it helps men feel manly. For all of the talk about male menopause the loss of testosterone isnt anything like the hormonal nose dive that women go through. Instead of essentially disappearing all at once testosterone levels usually decline by about  every year although they can drop more dramatically especially if a man becomes ill. Men diagnosed with unusually low levels of testosterone are sometimes treated with prescription testosterone injections patches or creams. Men who want to regain the levels of their younger days without a prescription may be interested in a different route overthecounter products that promise to boost testosterone naturally. TestoJack  a supplement from NOW Foods contains a blend of herbs including Eleutherococcus senticosus Tribulus terrestris and Eurycoma longifolia along with zinc magnesium and vitamin B among other ingredients. Users are instructed to take two capsules once or twice a day. Its available at many healthfood stores and you can expect to pay roughly  to  for a bottle of  capsules.   HGH Up a widely available supplement from Applied Nutriceuticals contains among other ingredients the herbs Chlorophytum borivillanium Mucuna pruriens and Huperzia serrata along with green tea magnesium and a vitamin B complex. Users are instructed to take five capsules every day on an empty stomach  three in the morning and two in the afternoon. A bottle of  capsules costs about . The claims The NOW website says TestoJack supports male reproductive function and healthy testosterone levels. The tribulus in the product is said to be especially helpful for virility. Despite the suggestive name of the product NOW doesnt claim that TestoJack actually increases testosterone says Neil Levin the companys nutrition education manager. It supports healthy testosterone levels he says. According to the label HGH Up promotes radical increases in growth hormone and testosterone production. The website says that it can provide the physiological benefits comparable to that of fully hormonal products while minimizing potential side effects. Though the product is marketed mainly to weightlifters and bodybuilders it has a growing following among older men looking for rejuvenation says Don Orrell president of Applied Nutriceuticals. For an older man who has low testosterone there is absolutely no downside to taking this he says. Orrell notes that the way in which the product boosts testosterone is a bit of a mystery  thats the magic pixie dust part he says  but he has no doubt that it works. The anecdotal evidence is overwhelming he adds. The bottom line Dr. John Morley a testosterone expert and director of geriatrics at St. Louis University says that theres not a lot of scientific evidence for any supplement that claims to boost or promote testosterone. And for him thats a real problem. These sorts of products have been around forever he says. As far as I know none of them have been proven to work in a carefully controlled trial. Some of the individual ingredients in these products have been tested with lessthanimpressive results. In a  study in the Journal of Strength and Conditioning Research Australian researchers found that giving rugby players daily doses of Tribulus terrestris for five weeks had no effect on their testosterone levels. Chlorophytum one of the ingredients in HGH Up has long been used as a supposed aphrodisiac for men. A search of the medical literature uncovers a single study suggesting that it may have testosteronelike effects including enhanced sex drive and stronger erections but the study was conducted on rats not humans. Morley often prescribes testosterone for men who have a significant deficit of the hormone a condition called hypogonadism. The prevalence of this condition is controversial  it depends on how one measures testosterone and defines normal levels  but Morley estimates that  to  of middleaged men dont have enough testosterone to feel their best sexually and otherwise. Even among these men about onethird dont respond to testosterone treatment. In other words testosterone is hardly a surefire remedy against the ravages of aging.   Overthecounter testosterone products may carry hidden dangers. A  study in Clinical Cancer Research found that two men taking a supplement called Teston developed unusually aggressive fastgrowing prostate cancer. Lab tests showed that the product contained hormones including testosterone that werent on the label a common issue with nonprescription products. The manufacturer quickly pulled it from the market. The problem with these sorts of supplements is that they dont have to meet the regulations of the Food and Drug Administration says Dolores Lamb a coauthor of the Teston study and professor of urology at Baylor College of Medicine in Houston. A man who thinks hes short on testosterone shouldnt be looking in a health food store for answers Morley says. He needs to go to a doctor to get checked out."