The battle against dementia should be refocused to the benefits of a Mediterranean diet and away from “dubious drugs”, a group of doctors and health experts said ahead of the G8 summit on the condition in London this week.

In a letter to the Health Secretary, Jeremy Hunt, they said persuading people to eat fresh fruit and vegetables, nuts, fish and olive oil was “possibly the best strategy currently available”.

They said a healthier diet could have a far greater impact in the fight to reduce increasing rates of the disease than the “dubious benefit of most drugs”.

Signatories to the letter included Professor Clare Gerada, former chair of the Royal College of GPs, and Professor David Haslam, chair of the National Obesity Forum.