Why you get white spots on your fingernails

Do you ever get little white spots or streaks across your fingernails? A lot of people do.

There's an old wives' tale about how the appearance of these marks indicates a calcium deficiency – a reason to drink your break-time milk. Some people even know the marks as 'milk spots'.

But, generally, you can rest assured that white dots – known scientifically as punctate leukonychia – on your nails are nothing sinister and they actually mean something very different.

Typically, they appear simply because there's been some trauma to the nail.

This doesn't have to be anything major. If you slam your nails in a door, of course, your nails are going to suffer. But even small things like excessively tapping them at your desk can cause them.

Chewing can also lead to white marks, as can flicking your pen, or even bashing them about while cleaning.

The little white spots form at the base of the nail bed. They grow out gradually before surfacing. By the time you notice them, you'll probably have forgotten what caused the trauma in the first place.

However, very occasionally the dots might tell you something more.

Puncate might not mean a lack of calcium but could suggest a zinc deficiency. Eating foods such as spinach, kidney beans, beef, and seeds is a good way to combat this.

In worse cases, the white marks might reveal signs of malaria, Hodgkin's disease, or sickle cell anemia. But these are extremely rare, and shouldn't really be your primary concern if you get normal leukonychia. There are usually other signals to tell you're unwell.

A time to worry would be if you were to see signs of leukonychia totalis. This is when the entire nail goes white. If you notice this happening, book an appointment with your GP as it could mean something like heart disease or diabetes.

Mees lines are also something to look for. This is when a white mark stretches across the whole nail, forming a sort of 'band'.

Got Mees' lines? You've likely been poisoned – probably by arsenic or thallium. If you can see them, though, you can't have been, because if you had, you'd almost certainly already be dead.