Extreme fitness risk dental decay, scientists have warned, as a new study finds half of elite athletes have rotting teeth.

A study of 352 Olympic and professional athletes found high rates of dental problems, even though they brushed their teeth on average twice a day.

Researchers believe the relentless intake of sports drinks, energy gels and bars are to blame, due to their high sugar content.

Intensive exercise may also prompt changes in saliva and the immune system that further exacerbates the damage.

Published in the British Dental Journal, the study included professional athletes across 11 sports, including football, rugby, cycling, rowing and gymnastics.

It found that 49.1 per cent had untreated tooth decay, with a large majority showing early signs of gum inflammation.

Almost a third - 32 per cent - reported that their oral health negatively impacted their training and performance.

Dr Julie Gallagher, a researcher at University College London, said: “We found that a majority of athletes in our survey already have good oral health related habits in as much as they brush their teeth twice a day, visit the dentist regularly, don’t smoke and have a healthy general diet.

“However, they use sports drinks, energy gels and bars frequently during training and competition.