The white spots you may sometimes notice on your fingernails are not caused by a calcium deficiency. They are called “leukonychia” and are very common. There is a congenital form of the condition, meaning that you’re born with it, but that’s very rare. Most of the time the white spots are simply a sign of some past injury to the matrix (base) of your nails. By the time they show up (about six weeks after the injury) you’ve probably forgotten all about banging or knocking your fingers. Sometimes, the injury can stem from a manicure that put excessive pressure on the base of a nail. White fingernail spots also can be a sign of an allergic reaction to nail polish or nail hardeners and, sometimes of a mild infection. Interestingly, the condition was first described in 1919 as a result of arsenic poisoning, but most people don’t have to worry about that!
Whatever the cause, white spots on fingernails are almost always temporary and will grow out as your nails grow. However, it can take more than eight months for nails to grow out completely so the spots may be around for a while.
Sometimes, a change in the appearance of your nails does indicate an underlying disease, but these changes would be more dramatic than just the occasional white spot. Nails that turn completely white, for example, can indicate liver disease, but by the time this happens, you probably would have other symptoms.
Incidentally, in addition to the myth that white spots in fingernails are a sign of calcium deficiency, you may also have heard that they indicate a zinc deficiency. That isn’t true either. Neither is the bizarre notion that the spots are due to eating too much Hellmann’s mayonnaise (I’m not making this up).
Andrew Weil, M.D.
Kristin R. Stevens, Paula F. Leis, Sarah Peters, Susan Baer, Ida Orengo. “Congenital leukonychia,” Journal of the American Academy of Dermatology, Volume 39, Issue 3,1998, Pages 509-512, ISSN 0190-9622. https://doi.org/10.1016/S0190-9622(98)70341-X. https://www.sciencedirect.com/science/article/pii/S019096229870341X
Ates D, Kosemehmetoglu K. “Acquired Leukonychia of the Distal Nail Plate: A Morphologic and Proteomic Analysis.” Am J Dermatopathol. 2020 Apr;42(4):261-264. doi: 10.1097/DAD.0000000000001473. PMID: 31415249.
Updated December 2021.