Researching the difference between the two kinds of arbutin, you can read in multiple places on the internet that alpha-arbutin is stronger in effect. Unfortunately, it's never backed up with a credible source. :( Our own research resulted in conflicting results: a study from 1995 found that alpha-arbutin is 10x as effective on mouse melanoma as beta-arbutin. On the other hand, a more recent study from 2015 found that beta-arbutin is more effective both on mouse melanoma cells and on human melanoma cells (btw, kojic acid was the most effective on human melanoma cells).
None of the studies we could find is in-vivo (made on real people) anyways, so who knows. We think you cannot go wrong with trying both beta- and alpha-arbutin and see if one works better for you than the other.
- Biological and Pharmaceutical Bulletin, Vol. 27 (2004) No. 4 P 510-514, Inhibitory Effects of α-Arbutin on Melanin Synthesis in Cultured Human Melanoma Cells and a Three-Dimensional Human Skin Model
- Masataka Funayama, Hirokuni Arakawa, Ryohei Yamamoto, Toyokazu Nishino, Takashi Shin & Sawao Murao (1995) Effects of α- and β-Arbutin on Activity of Tyrosinases from Mushroom and Mouse Melanoma, Bioscience, Biotechnology, and Biochemistry, 59:1, 143-144
- Planta Med Lett 2015; 2(01): e39-e41, Assessment of the Effect of Arbutin Isomers and Kojic Acid on Melanin Production, Tyrosinase Activity, and Tyrosinase Expression in B16-4A5 and HMV-II Melanoma Cells