Over recent years many pieces of research have identified a link between adherence to a Mediterranean diet and a lower risk of age-related disease such as dementia.
Until now there has been no systematic review of such research, where a number of studies regarding a Mediterranean diet and cognitive function are reviewed for consistencies, common trends and inconsistencies.
A team of researchers from the University of Exeter Medical School, supported by the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care in the South West Peninsula (NIHR PenCLAHRC), has carried out the first such systematic review and their findings are published in Epidemiology
The team analysed 12 eligible pieces of research, 11 observational studies and one randomised control trial. In nine out of the 12 studies, a higher adherence to a Mediterranean diet was associated with better cognitive function, lower rates of cognitive decline and a reduced risk of Alzheimer's disease.
However, results for mild cognitive impairment were inconsistent.
A Mediterranean diet typically consists of higher levels of olive oil, vegetables, fruit and fish. A higher adherence to the diet means higher daily intakes of fruit and vegetables and fish, and reduced intakes of meat and dairy products.
The study was led by NIHR PenCLAHRC researcher Iliana Lourida. She said: "Mediterranean food is both delicious and nutritious, and our systematic review shows it may help to protect the ageing brain by reducing the risk of dementia. While the link between adherence to a Mediterranean diet and dementia risk is not new, ours is the first study to systematically analyse all existing evidence."
She added: "Our review also highlights inconsistencies in the literature and the need for further research. In particular research is needed to clarify the association with mild cognitive impairment and vascular dementia. It is also important to note that while observational studies provide suggestive evidence we now need randomized controlled trials to confirm whether or not adherence to a Mediterranean diet protects against dementia."