BAKUCHIOL: What is it and do you need it in your skincare?
This is the claim: ‘Bakuchiol is the gentler yet just as powerful sister to retinol.’ Bakuchiol is derived from the seeds and leaves of the plant psoralea corylifolia. It is claimed that it is a ‘functional analogue of retinol’ based on its effects on gene expression profiles of skin cells in a test tube.
This is an example of how Big Skincare takes an unsubstantiated claim for an ingredient, spins the ‘research’ to make it sound like ‘a new skincare hero,’ creates products and marketing buzz and ends up making millions of pounds selling, basically, just another moisturiser.
Aside from the fact that OTC retinols have no high-quality evidence to back up any of their skincare claims, is there any evidence to support that bakuchiol has an impact on skin at all?
The Answer? No.
Despite its presence in an array of cosmetic skincare products, there have been only two studies performed looking at bakuchiol 0.5% cream and its effects on the signs of skin aging.
The first one (Chaudhuri + Bojanowski 2014) had 17 females apply bakuchiol 0.5% cream as a finished skincare product twice daily for 12 weeks. There are many methodological issues with this ‘trial,’ but the major problem is that there is no vehicle control. The vehicle response in all skincare studies can range from 35% to 80% - that means that the cream without the ‘active’ in it is effective in improving the signs of aging in a large number of the subjects because moisturising alone every day with any moisturiser improves the signs of aging (skin roughness, appearance of fine lines, smoothness of skin, etc). You HAVE to have a vehicle control in an efficacy study of anything in order to show that your active is more effective than just the cream vehicle. Without a vehicle control, the ‘results’ are just completely meaningless. So the study showed that the signs of skin aging improved with the use of the bakuchiol cream after 12 weeks. You would probably have had the same results if they had used plain old Vaseline twice daily for 12 weeks.
The other one (Dhaliwal et al 2018) compares bakuchiol 0.5% cream to retinol 0.5% cream over 12 weeks in 44 patients. This study was published in the BJD which is a reputable journal and it has many positive aspects to its design (clear primary endpoints, power calculation, correction for multiple comparisons) but there are two big issues:
This is meant to be a double-blinded study (which means both the investigators and the subjects don’t know which treatment they are using) but the protocol is that retinol is used once a day at night and the bakuchiol is used twice daily. How was this blinded? Did the retinol group use a vehicle in the morning and retinol at night to ensure it was indeed double blinded? This is not explained and could represent an important source of bias.
The study design is that of a superiority study but the hypothesis stated in the paper is that bakuchiol is similar in efficacy to retinol, not that it is better. To show similar efficacy you need to do a non-inferiority trial. The study did not show that bakuchiol is better than retinol so therefore this is a failed or negative study. The investigators conclude that ‘bakuchiol is comparable with retinol in the ability to improve photoaging’ but that is a misleading and incorrect statement because that is not what the study showed; it was designed to show superiority and it did not show that. This sounds like a ‘minor’ technical issue but it isn’t: the hypothesis does not agree with the study design. Why would that be? Probably because they knew that bakuchiol would not show superiority so if that had been stated as the hypothesis, they would have been forced to say that this was a negative study. And that wouldn’t make great PR. Also, to show similar efficacy you need to use a non-inferiority design and that would necessitate more patients, more time and a lot more money.
These are what I call ‘marketing’ studies – they are performed purely to be used as part of the marketing and sale of a product, not to provide any real, informative scientific data. Is bakuchiol the new ‘skincare hero’? Not based on these publications. It is concerning to see doctors/dermatologists promoting the use of this ingredient when the evidence-base for it just doesn’t exist. In my opinion, that is poor practice. We shouldn’t be helping Big Skincare propagate grossly unsubstantiated claims.
Interestingly bakuchiol has already been shown to be a contact allergen by Malinauskiene et al (2019) in a case report of a 33-year old woman with a 1-year history of dermatitis of her face secondary to a 0.1% bakuchiol cosmetic product.
Bottomline: Don’t bother with bakuchiol – it has even less ‘evidence’ for its ‘effectiveness’ than OTC retinols