A diet rich in fish may help improve the cognitive function of middle-aged men, new findings suggest.

According to a study conducted by scientists at the University of Manchester, vitamin D intake from eating fish can benefit the brain by reducing the risk of degeneration.

The researchers found that men aged between 40 and 79 with higher levels of vitamin D performed consistently better in neuropsychological tests.

Lead author of the report, Dr David Lee from Manchester's School of Translational Medicine, revealed a link between slower information processing and lower levels of the fat-soluble vitamin.

"The positive effects vitamin D appears to have on the brain need to be explored further but certainly raise questions about its potential benefit for minimising ageing-related declines in cognitive performance," he explained.

Oily fish such as sardines, herring, mackerel, trout and salmon are all rich sources of vitamin D and omega 3 fatty acids and should incorporated into balanced diet plans where possible for optimum health, the Food Standards Agency suggests.