The battle against dementia should be refocused away from “dubious” drugs to the benefits of a Mediterranean diet, a group of British doctors and health experts say ahead of an international summit.

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

But it was being largely ignored because of the “low awareness and prestige given to diet by many in the medical profession”, they warned, calling for an education program.

Dementia experts from G8 countries will gather in London this week for a meeting convened by David Cameron as part of the UK’s presidency of the group of leading economies.

Hunt has called dementia a health and care “time bomb” with the number of people living with the condition expected to triple worldwide to 135 million by 2050, according to a recent report.

Critics are also concerned about high levels of anti-psychotic drug prescription.

Among signatories to the letter were former chair of the Royal College of General Practitioners, Professor Clare Gerada, the chair of the National Obesity Forum, Professor David Haslam, Professor of Clinical Epidemiology at the University of Liverpool Simon Capewell and London cardiologist Dr Aseem Malhotra.

They said successfully encouraging people onto a healthier diet could have a “far greater impact in the fight to reduce the dramatic increasing rates of the disease than pharmaceutical and medical interventions” than the “dubious benefit of most drugs”.

It can also protect against coronary heart disease, hypertension and diabetes.

Research by the University of Exeter’s Medical School found a majority of studies suggested the diet could improve cognitive function, lower rates of decline and reduce the risk of Alzheimer’s disease.

However, results for mild cognitive impairment – the stage before Alzheimer’s or dementia, when someone could be experiencing some cognitive difficulties – were inconsistent.

“The evidence base for the Mediterranean diet, in preventing all of the chronic diseases that is plaguing the western world is overwhelming,” Dr Malhotra said.

“This includes cardiovascular disease, type 2 diabetes, Alzheimer’s and cancer.

“Policy makers and the public need to know that such a diet is far more potent than the often dubious benefit of many medications and without side effects.”

Dr Simon Poole, a leading advocate of the Mediterranean diet who organised the letter, said: “Educating all generations, including our children, in the importance of a good diet in maintaining health in old age is a project which will take years, but is absolutely essential.”