The middle toenail on my left foot has been
growing out curved during this past year,
and I am afraid it might cause an ingrown nail
sometime. Here is a pic of the nail :

The fourth smaller toe (the next one on the
left) also has a curved nail, but is milder
and is not so likely to cause an ingrown nail.

Does anyone know what might cause a nail
to grow out curved ? I've read that vitamin B12
deficiency might be one possible cause.

Can the curvature be corrected, say by a podiatrist ?