Carnosic acid, the antioxidant found in rosemary leaves, may significantly improve wound healing and reduce scarring, according to new research published in JCI Insight.
The inspiration for this study stemmed from TikTok and Instagram. After seeing beauty influencers and other social media users touting the skin-healing benefits of homemade rosemary extract serums and products with rosemary, Penn undergraduate student Jiayi Pang and Penn PhD candidate Emmanuel Rapp Reyes decided to test it out under the guidance of Thomas Leung, MD, PhD, an Associate Professor of Dermatology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, PA.
“We hypothesized there was likely something real behind the hype because rosemary contains many antioxidants,” says Pang, Co-lead author of the study, in a news release. “But we knew in order to really uncover its potential, we needed to prove its healing properties and uncover how exactly it was facilitating healing.”
Conducting the research in mice, the researchers made cream with carnosic acid to accelerate wound closure and restore hair follicles, oil glands, and cartilage. They also found that a particular nerve sensor in the skin previously identified as essential to scarless healing, TRPA1, was critical for stimulating the healing in this instance, too. When tested in mice without the TRPA1 sensor, which previous research showed is responsible for scarless healing, carnosic cream lost its impact.
“We also identified other herbs, such as thyme and oregano, that may activate TRPA1. But rosemary stood out for its potency and safety,” says Rapp Reyes, Co-lead author of the study. “Other natural ingredients, such as mustard oil, or the topical medication imiquimod, are known to also stimulate the TRPA1 receptor, but unlike rosemary, those can cause irritation and inflammation.”
The researchers also found a localized effect from rosemary; scarless healing only occurred when carnosic acid cream was applied to the site of the injury but not when it was applied to skin far from the wound.
Don’t try this at home. Individuals should speak with their doctors before incorporating rosemary skincare products in their daily regimens or mixing up their own rosemary-based concoctions, the study authors note. Nevertheless, given rosemary’s accessibility and low cost, the researchers hope their findings will inspire further investigation into its use in human wound care, especially for patients at risk of excessive scarring.
“If rosemary is part of your skincare regimen and you think it’s working, it likely is,” says Dr. Leung.
PHOTO CAPTION: Penn undergraduate student Jiayi Pang (left) and Penn PhD candidate Emmanuel Rapp Reyes (right) found that rosemary can help skin wounds heal without causing scars.
PHOTO CREDIT: Courtesy of Penn Medicine
