Renu Renual Serum Refill. Joico Re:Nu Age Defy - Re:nual Serum is the first-of-its kind innovative formula that actually reverses the graying process, the number one sign of aging hair. This renewal serum, formulated by Shiseido, inhibits the development of new grays as it creates an optimal environment for the growth of healthier, shinier, more youthful 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 hair's youthful color and texture. With initial use of Re:nual Serum, you can expect stronger, healthier-feeling hair in two-to-six weeks and fewer new gray hairs in two-to-four months. An actual reduction in gray hair and a gradual restoration of natural hair color can occur after six months. Over a 5-month period, Re:nual Serum users noticed 50% less NEW gray hair than non-users. With continued use, this exclusive formula is scientifically proven to: slow down the graying process, restore hair's soft, silky, manageable texture, and create the optimal environment to grow healthy, lustrous, radiantly youthful hair.