The reports said the international team believes a simple supplement of folic acid, which is found in many green vegetables and can be taken as a vitamin tablet, could shelter potential sufferers against the debilitating disease, the main cause of senile dementia.
"It is a very promising finding," the Sunday Telegraph quoted one of the research team, Professor Helga Refsum of Norway's Bergen University, as saying. "We need something to go for, and the idea of reducing the risk of Alzheimer's disease by diet is a promising hypothesis."
Refsum stressed that the results had so far only revealed an association, not a direct cause and effect, and pointed out that many older people suffer from conditions that can be exacerbated by taking folic acid.
Reporting from London, CBS News Correspondent Mark Phillips reports that Alzheimer's researchers are approaching the study with caution.
"My own view at this stage is we should be cautious," Harry Cayton of the Alzheimer's Disease Society told Phillips. "It is most likely that Alzheimer's disease will turn out to be a disease that has many different levels of damage to the brain and which also has many causes. There will never be a simple answer to Alzheimer's disease. It will never be, I'm afraid, as simple as just eating the broccoli."
The research is to be unveiled at an international scientific conference in the Netherlands this week.
The newspapers said the study of hundreds of British patients revealed a link between Alzheimer's and high levels of a chemical produced by the body that is known to be affected by diet.
The discovery, made by an international team co-ordinated at Oxford University, opens the way to a simple blood test for identifying those most at risk.
It also raises the possibility of avoiding the disease altogether by cutting levels of a compound known as homocysteine. This could be brought about by increasing a patient's intake of folic acid.
The disease affects 500,000 people in Britain and causes progressive memory loss. It is the fourth commonest cause of death in the Western world.
"If the interpretation being placed on these results is correct, it is potentially dynamite," the Sunday Times quoted one senior scientist as saying.