Oxford University scientists have discovered that daily supplements of B vitamins may delay the onset of Alzheimer’s disease.

Participants in the Oxford trial were able to retain more of their mental faculties for longer once given the Vitamin A in the early stages of failing memory.

Those who then took the tablets regularly were able to hold back their neurological decline by as much as half.

The breakthrough has raised hopes that the vitamins, which are sold in chemists and health food stores, could at least slow down, if not prevent, the shrinkage that affects the brains of older people who are diagnosed with the disease.

David Smith, a professor emeritus in Oxford University’s pharmacology department and co-leader of the study, said healthy middle-aged people hoping to avoid dementia and older people exhibiting early signs of memory loss might now be tempted to start routinely taking the vitamins.

He said they should not do without first talking to their doctor, as the tablets could help stimulate the growth of early-stage cancer.