Features key ingredients: biotin and healthy fats. A study showed women who were given biotin had Increased nail thickness, reduced splitting, and made the irregular dorsal surface of the nails more regular in women with brittle nails.The composition of blackcurrant seed oil (BCSO) corresponds to the recommended dietary intake of EFAs, and as a dietary supplement could, in small doses, modify the imbalance of EFAs in an efficient way in cases of skin conditions associated with an altered intake of EFAs.