Libido/Strength/ Stamina/Vitality. Helps to. Increase sex Drive. Enhance Muscle Mass. Boost Free Testosterone. Reclaim Your Strength, Stamina, and Sexual Performance. As you age, testosterone levels can decrease resulting in lowered muscle mass and decreased libido All natural Nugenix helps your body restore testosterone levels by delivering a proprietary testosterone-boosting compound of Testofen, L-Citrulline, and Tribulus terrestris. Clinical studies have shown Testofen to increase free testosterone levels by over 98%. Nugenix also incorporates vitamins B12, B6 and Zinc to augment the benefits of Testofen. As the primary male sex hormone, testosterone plays a key role in maintaining active sexual performance, plus overall health, relationships and well-being.