Consumption of a traditional Mediterranean-type diet – rich in foods such as seafood, fruit, and nuts – is associated with a reduced risk of dementia, reports a study published in BMC Medicine. Individuals with a higher adherence to a Mediterranean diet had up to 23% lower risk for dementia compared with those who had lower adherence to a Mediterranean diet.

Diet may be an important modifiable risk factor for dementia that could be targeted for disease prevention and risk reduction but previous studies exploring the impact of a Mediterranean diet have typically been limited to small sample sizes and low numbers of dementia cases. Oliver Shannon and colleagues analysed data from 60,298 individuals from the UK Biobank who had completed a dietary assessment. The authors scored individuals using two measures for adherence to the Mediterranean diet. During the mean follow-up of 9.1 years there were 882 cases of dementia. The authors also considered each individual’s genetic risk for dementia by estimating their polygenic risk, a measure of all the different genes that are related to risk of dementia.

The authors found that participants with the highest adherence to the Mediterranean diet had a 23% lower risk of developing dementia in comparison with those with the lowest adherence score, equivalent to an absolute risk reduction of 0.55%. There was no significant interaction between the polygenic risk for dementia and adherence to a Mediterranean diet, which the authors suggest may indicate that the association of greater adherence to a Mediterranean diet and a reduced dementia risk remains, irrespective of the individual genetic risk for dementia. This finding was not consistent across all the sensitivity analyses and the authors propose further research is needed to assess the interaction between diet and genetics on dementia risk.

The authors caution that their analysis is limited to individuals who self-reported their ethnic background as white, British or Irish, as genetic data was only available based on European ancestry, and that further research is needed in a range of populations to determine the potential benefit. They conclude that, based on their data, a Mediterranean diet that has a high intake of healthy plant-based foods may be an important intervention to incorporate into future strategies to reduce dementia risk.