An effort to change people’s diets would be more effective in preventing dementia than focusing on drug treatments, a multinational group of high-profile physicians said in a recent letter to U.K. Prime Minister David Cameron and Health Secretary Jeremy Hunt.

Numerous studies have shown the long-term cognitive benefits of a Mediterranean-style diet rich in fruits, vegetables and olive oil, while most dementia drugs offer “dubious benefits,” the letter stated.

The 11 signatories included doctors from the United States, United Kingdom, France, Italy and Greece, according to The Telegraph. They were organized by Simon Poole, M.D., a long-time proponent of the Mediterranean diet and former chairman of the Cambridge Medical Committee.

Poole took aim at pharmaceutical companies in comments to the press after the letter was delivered. He said these companies “talk up their medicine” but the drugs fall short in practice, and the promotion of healthy diets will have a greater effect in preventing dementia in future generations, according to the Daily Mail.

Other prominent signatories included Clare Gerada, M.D., former chairman of the Royal College of General Practitioners, and David Haslam, M.D., chairman of the National Obesity Forum.

The group delivered their letter in the run-up to the G8 Dementia Summit, which takes place today in London. Cameron explained the purpose of the summit and reaffirmed his commitment to battling dementia in a Sunday Express column Sunday.