Shea butter is a common moisturising ingredient but AAK’s Jari Alander claims that its efficacy has never been properly tested.
“As one of the biggest buyers of shea kernels from Africa today we thought we would scientifically test the ingredient,” he told CosmeticsDesign.
Unlike active ingredients, emollients are not usually tested for efficacy.
However, according to Alander, the industry is becoming increasingly strict on the data needed to back up efficacy claims, and companies have less freedom to make statements that have not been proven.
Soft shea butter
The company’s research investigated the Sheasoft ingredient, which combines a high melting point with a soft consistency at room temperature and focused on the short term moisturising effect.
Skin care manufacturers need to provide short term effects as daily showering can remove skin lipids and put skin under stress, explained Alander.
AAK’s researchers stimulated daily washing by treating the skin of volunteers with ethanol causing an increase in trans-epidermal water loss (TEWL). They then applied the Sheasoft and compared its moisturising properties to a mineral oil equivalent.
According to Alander, the TEWL rapidly recovered after the application of Sheasoft and after two hours returned to basement levels. After three and four hours the barrier properties of the skin were improved on pre-treatment levels.
With the mineral oil, there was a slower recovery and starting values were not recovered, he said.
AAK also investigated the moisture levels deeper in the skin using a corneometer, finding that the sheasoft led to a consistent increase over four hours. The mineral oil also led to an increase in moisture levels as measured by the corneometer. However, this increase was not as marked as that of the shea butter, according to Alander.
February 2018 update
Since this article was first written, in May 2009, there has been a significant body of research carried out on the moisturizing properties of Shea Butter.
In response to this, the research team at consumer facing digital publication Healthybutsmart.com delved into 13 of the highest quality scientific papers currently available on the subject.
The results of that research were compiled as a comprehensive report, which can be viewed by clicking here.