What are white stains on nails?
The reasons why you get white marks
If you notice that there are white stains on your nails, do not be alarmed. It is not life-threatening and will not really affect your lifestyle apart from the strange feeling of having your nails smeared with something.
It is often said that white marks are caused by calcium deficiency. This is not true. Another theory for the white stains is the lack of zinc in the body. Again, this is just a supposition that has no medical basis.
The real cause
The truth is, white marks on the nail are caused by a past injury to the base or matrix of the nails. This is a condition called, leukonychia. You might have banged or knocked your fingers or hands and have probably forgotten all about it. Usually, the white marks do not show up until after 6 weeks.