The actual reason of those white marks on our nails isn't Calcium deficiency

[Hamartia Antidote]

Not a single white mark on my nails. I drink a jug of milk everyday.

Same here and I can't remember ever having lines in my nails even as a kid.

 

[somebozo]

Zinc Deficiency also causes these spots

 

[paki_rambo]

used to have HB deficiency in childhood and there were lot of the marks on my nails.Eventually they disappeared by drinking milk

 

[Nakash Ahsan]

It indicates protein deficency specifically albumin one that is found in white of egg