Renu 4 Month Renual Serum Program Softness and Manageability. Joico Re:nual Serum is the most advanced solution for graying hair. The result of 10 years of the most advanced hair care research and development, this revolutionary scalp treatment formulated by Shiseido Laboratories slows the graying process to keep gray hair at bay and maintain hairs youthful color and texture. With continued use, this exclusive formula is scientifically proven to slow down the graying process, restore hairs soft, silky, manageable texture and create the optimal environment to grow healthy, lustrous, radiantly youthful hair. Over a 5 month period, Re:nual Serum users noticed 50 percent less NEW gray hair than non users.