I read the B Vitamin Biotin can help 2.5 mg. daily. Brittle Nails could be a sign of an underactive Thyroid. Perhaps your Primary care Physcian could examine this. Evening Primrose Oil has Gamma Linolenic Oil which has shown to help Brittle Nails. Fish Oils and I think Flax (Linseed Oil) can also help. Brittle Nails can be a sign of a poor diet, so you may want to make substitution changes. Comments from our Resident Physcians in the CR who have a proclivity to Natural Remedies will be appreciated. Smart Cookie I hope this helps good luck.
