Here’s what Professor Hallux has to say:
Fingernails do lots of important things – they protect our fingers, help us pick up small objects and scratch any itches we have. So biting this nails all the time make them less effective at doing these jobs.
Most importantly, just think about everything you touch over the course of the day. Bacteria and germs are constantly getting in contact and staying on your fingernails.
So if you bite your nails you’re putting those germs in your mouth and it could lead to you feeling poorly.