London - Toenails, like fingernails, are thought to be an evolutionary leftover from claws. Their function is to protect the toes from damage. They endure being rubbed against shoes and stubbed, and bacteria and fungi, so are vulnerable to problems.

WHAT CAN GO WRONG:

* Nails become ingrown when their edge grows into skin. Contributing factors are tight shoes or socks and injury (a stubbed toe or torn nail). Treatment involves having the ingrown part removed — but it can recur.

* A fungus (onychomycosis) causes white, brown or yellow discolouration and thickening. Oral anti- fungal medicine can help. Green nails can be due to a bacterial infection. A black or brown nail which hasn’t been caused by bruising can very rarely indicate skin cancer.

* Doctors often examine toenails as they can indicate problems in other parts of the body. Any change in colour can be a sign of cardiac disease, auto-immune disease or metabolic disorders such as chronic liver disease, renal failure, or even lymphoma.

According to podiatrist Mike O’Neill, very pale toenails could indicate the heart is having trouble pumping blood to the extremities. Another sign to look out for in this case is ridges on the nail or losing the hairs on your toes, as this can mean underlying vascular disease.

* Spoon-like or indented toenails can indicate the iron deficiency anaemia. Ridges across the nail can occasionally be a sign of rheumatoid arthritis. - Daily Mail