Man dies of heart attack caused by ... nail biting

It's a good thing you listened to your mom when she told you not to bite your nails: The bad habit ended up costing one UK man his life.

John Gardener, a 40-year-old amateur football referee, bit his fingernails so badly that they bled—leading to an infection that turned septic and caused a fatal heart attack, the Mirror reports.

Gardener may have become immune to the pain after years of nail-biting; his doctor says the man's fingernails were "always in poor condition and ... often bleeding," and he'd lost nearly all feeling in them.

The habit had only gotten worse in recent years, as he also suffered from anxiety and depression. He was admitted to the hospital in September with septicemia, and was initially treated just with antibiotics because he didn't want to lose his finger, but eight days later, doctors were forced to amputate the tip.

Even so, he died two weeks after being admitted, despite showing signs of improvement and no fever. His surgeon says Gardener's death was "upsetting and shocking." His mother insists, "there could've been more done to help him." The family is taking action against the hospital, the Express reports.

Gardener, who was also diabetic, had previously had his lower right leg amputated due to leg ulcers. (Click to read about how another bad habit, peeing in the pool, can be dangerous.)