There is insufficient evidence that a healthy diet protects against dementia, health officials have declared in a new report.
The Scientific Advisory Committee on Nutrition warned there is no magic nutrient or supplement that slashes the risk of the neurological disorder.
Scores of medical trials that delved into the link between diet and dementia were examined by the Government advisers.
The report concluded that adhering to a Mediterranean diet is associated with a reduced risk of mild cognitive impairment and dementia.
However, it stressed most evidence behind this comes from observational studies - meaning no firm conclusions can be drawn about cause and effect.iPhone transfer software
The Scientific Advisory Committee on Nutrition warned there is no magic nutrient or supplement that slashes the risk of dementia
They also found there is little evidence to draw any conclusions on the association between other 'healthy' diets and risk of cognitive impairment.
And there is not enough evidence currently to confirm a link between taking B, C and E vitamins or omega-3 fatty acids and risk of dementia.
The authors also found that the evidence is 'limited' and indicates that there is no association between caffeine intake and cognition over the longer term.
SACN - comprised of leading researchers from British universities - advises Public Health England and other UK Government organisations on nutrition.
Following the publication of the report, the committee has now called for more scientific trials to establish links between diet and dementia.
Commenting on the review, PHE said the report broadly supports existing advice to eat healthily.
Eating a healthy diet can help people to achieve lifestyle factors linked to a lower risk of dementia such as maintaining a healthy weight and blood pressure.
But PHE said overall, there is not enough evidence to support a relationship between prevention of dementia and diet.
Dr Alison Tedstone, chief nutritionist at PHE, said: 'This report broadly supports existing advice to eat a healthy diet as depicted in the Eatwell Guide.
'However, the report indicates that, overall, there isn't currently enough evidence to support a relationship between diet and the prevention of dementia.'
NHS advice to reduce the risk of dementia is to eat a healthy diet, maintain a healthy weight, exercise regularly, do not drink too much alcohol, stop smoking and maintaining a healthy blood pressure.
The report indicates that, overall, there isn't currently enough evidence to support a relationship between diet and the prevention of dementia
Dr Alison Tedstone, chief nutritionist at Public Health England
Dr Matthew Norton, director