A Mediterranean diet could help to stop our brains shrinking as we age, researchers say.
A study of people with an average age of 80 showed that those who had followed the diet, which is rich in vegetables, fruit and olive oil, had bigger brains.
It suggests that people could prevent their brains shrinking simply by changing their diet.
Eating more fish and less meat was also associated with less brain shrinkage, the US study of 674 people found.
Lead scientist Dr Yian Gu, of Columbia University in New York, said: 'These results are exciting, as they raise the possibility that people may potentially prevent brain shrinking and the effects of ageing on the brain simply by following a healthy diet.'
'The magnitude of the association with brain measures was relatively small, but when you consider that eating at least five of the recommended Mediterranean diet components has an association comparable to five years of ageing, that is substantial.'
Dr James Pickett, of the Alzheimer's Society, said: 'There is an increasing amount of evidence that eating a healthy diet, rich in fish, vegetables, legumes and nuts, is good for your brain.'
However, he insisted that this study, which was published in the journal Neurology, 'does not prove that a Mediterranean-style diet can stop your brain from shrinking as you age'.
He added: 'Other key ways to keep your brain healthy is to take as much physical exercise as you can, stop smoking and keep your blood pressure in check.'
Brain shrinkage is seen in patients with dementia.
But Dr Laura Phipps, from Alzheimer's Research UK, said: 'While this study suggests there is an association between eating a Mediterranean diet and brain volume in healthy older people, we don't know whether these particular food choices alter dementia risk.
'It's hard to know from this study what the underlying reason for the link between diet and brain volume might be, and what other factors may be involved.'