A commentary article published in the Journal of Cosmetic Dermatology outlined the methodologic flaws of studies claiming to support the anti-aging effects of bakuchiol. Derived from the plant psoralea corylifolia, bakuchiol is purported to be a functional, gentler alternative to retinol. However, the studies describing bakuchiol’s skincare efficacy are sparse at best, with major methodology issues, noted the paper’s author. Dermatologists should avoid promoting products without first clinically appraising them, it was suggested.
To date, just 2 clinical studies have been performed to test the efficacy of bakuchiol cream for cosmetic dermatology. The first study comprised a cohort of 17 women, who were instructed to apply the cream twice daily for 12 weeks. The trial reported improved “smoothness of skin” and decreased appearance of lines within 12 weeks. However, the lack of a vehicle/placebo group is a major study flaw, wrote the commentary author. The vehicle used to apply bakuchiol likely had its own physiological effect on the skin, and the act of moisturizing alone could account for improved skin appearance. In addition, no baseline objective measures of “smoothness” were reported, preventing any assertion that bakuchiol caused changes from baseline. The small sample size also limits data generalizability.
The second study compared bakuchiol 0.5% cream with retinol 0.5% cream during 12 weeks in 44 patients. Although this study had clear primary endpoints and used robust statistical tools, it still had methodological drawbacks, it was pointed out. First, although the study claimed to be “blinded,” retinol was applied once daily at night and bakuchiol was applied twice daily. In this way, participants could have been aware of their treatment assignment, which could introduce bias, it was noted. Secondly, although the study claimed that bakuchiol displayed “comparable” effects to retinol in improving photoaging, the trial design does not support this assertion. A non-inferiority study is necessary to assert “comparable” efficacy of 2 agents. Instead, investigators performed a superiority study. As a superiority study, the trial had a null result: bakuchiol was not superior to retinoid. Instead, however, investigators reported results as if the trial were positive, asserting that bakuchiol was comparable to retinoid. The paper’s author maintains that this claim is not backed by the study design and should not be considered putative evidence of bakuchiol’s efficacy.
These 2 studies represent what the commentary’s writer describes as “marketing studies”: performed with an aim to promote bakuchiol rather than interrogate its effectiveness. To date, no high-quality clinical trials support the cosmetic utility of bakuchiol. Also, its safety profile is unclear: 1 patient reported a full year of dermatitis of the face secondary to 0.1% bakuchiol product. Its role as a contact allergen requires further study.
“As the billion-dollar skincare industry continues its rapid growth, we must both maintain the integrity of our profession and protect the consumer from being misled by critically appraising products that make significant medical claims,” the commentary author wrote.
Spierings NMK. Cosmetic commentary: is bakuchiol the new “skincare hero”? [published online September 4, 2020]. J Cosmet Dermatol. doi: 10.1111/jocd.13708