Results of a four-year trial have suggested that a Mediterranean diet, supplemented with either olive oil or nuts, may help thinking skills in some older people. The study is published on Monday 11 May in the journal JAMA Internal Medicine.
The study, run by researchers at the Biomedical Research Institute of Barcelona, in Spain, included data from 334 people with an average age of 67. None of the participants had problems with thinking or memory, but all were considered to be at high risk of cardiovascular disease and had been recruited to the PREDIMED trial – a much larger study investigating whether diets could prevent cardiovascular disease. As part of this trial, participants were assigned to one of three diets:
- a low-fat diet
- a Mediterranean diet (high in fruit and vegetables, fish, nuts and olive oil), with participants given 1 litre of extra virgin olive oil per week
- a Mediterranean diet with participants given 30g of nuts per week
At the start and end of the study, participants were given a series of tests to measure their memory and thinking skills. When the researchers analysed the results, they found that those on the low-fat diet tended to have worse scores in these tests after four years, while the two Mediterranean diet groups were more likely to have maintained their scores on some tests over the four years.
However, the results also showed that for the group assigned to a Mediterranean diet with olive oil, 13% developed mild cognitive impairment (MCI) – a condition that causes memory and thinking problems, although not to an extent that could be classed as dementia. For the Mediterranean diet with nuts, 7% of the group developed MCI, while 13% of the low-fat group developed the condition.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, the UK’s leading dementia research charity, said:
“The results of this trial appear to be encouraging but the effects seen were very subtle and as the researchers themselves point out, more work is needed to understand these findings fully. This study looked at a relatively small subset of people involved in a larger trial, but this trial was not designed to assess the effects of diet on memory or thinking, and these results should therefore be treated cautiously. It’s important to note that the people in this study did not have dementia, and this trial does not tell us whether a Mediterranean diet could prevent the condition. These findings suggest a need for much larger trials to understand better the effects of changes in diet on memory, thinking and dementia risk.
“With 850,000 people affected by dementia in the UK and that number on the rise, research into preventions is crucial to help people to make lifestyle choices that could reduce their risk of the condition. While there is currently no certain way to prevent dementia, evidence suggests the risk can be lowered with a healthy lifestyle including a balanced diet, regular exercise, not smoking, and keeping weight and blood pressure in check.”