UK Edition
No firm proof that a healthy diet protects against dementia, government scientists conclude
There is no firm evidence to conclude that a healthy diet protects against dementia, government advisers say.
The Scientific Advisory Committee on Nutrition (SACN) said there is no proof that any specific nutrient or food supplement can ward off the brain-wasting disease.
The review considered dozens of trials examining the role of different types of diets and supplements.
It said several studies found those eating the Mediterranean diet - a regime rich in fish, vegetables, fruit and legumes - were less likely to develop dementia
But the review concluded that such evidence was “observational” - meaning it could not demonstrate that the healthy eating habits were the reason for the lower rates of disease.
Those choosing such a diet may have had other habits - such as higher exercise levels - which are also linked to a lower rate of dementia.
Previous research has suggested omega-3 fish oils and vitamin B may ward off the brain-wasting disease. But the review said: “There is no evidence that specific nutrients or food supplements affect the risk of cognitive impairment or dementia”.
The committee advises the Department of Health and Public Health England (PHE) on health matters.
Dr Alison Tedstone, PHE chief nutritionist, said: “This report broadly supports existing advice to eat a healthy diet, as depicted in the Eatwell Guide.
“However, while the report indicates there isn’t currently enough overall evidence to support a relationship between diet and the prevention of dementia, a healthy balanced diet is vital in achieving a healthy weight and avoiding obesity-related health problems - including type 2 diabetes, heart disease and some cancers.”
Britain’s obesity rates are the worst in western Europe, with rates rising even faster than those in the US.
The SACN report concluded that that adherence to a Mediterranean dietary pattern is associated with a reduced risk of mild cognitive impairment and dementia, including Alzheimer's disease.
But the authors stressed that most evidence behind this finding comes from observational studies - which means that no firm conclusions can be drawn about cause and effect - and they called for more evidence to establish the link.
And there is not enough evidence to confirm a link between taking individual nutrients - including B vitamins, vitamins C and E and omega-3 fatty acids - and risk of dementia.
Dr Matthew Norton, director of policy and impact at Alzheimer's Research UK, said: "The brain, just like other parts of the body, can be affected by the way we live our lives. While a balanced diet is one way to maintain a healthy brain, the best current evidence suggests supplements or nutrients offer no additional preventative value.
"Wider evidence points to a number of other lifestyle factors that can also play a role. Not smoking, staying mentally and physically active, only drinking in moderation and keeping blood pressure and cholesterol in check are all ways to keep the brain healthy into later life."