A new study has suggested that eating green leafy vegetables can help keep mental abilities sharp.

Something as easy as adding more spinach, kale, collards and mustard greens to your diet could help slow cognitive decline, according to Rush University Medical Centre's research, which also examined the nutrients responsible for the effect, linking vitamin K consumption to slower cognitive decline for the first time.

Losing one's memory or cognitive abilities is one of the biggest fears for people as they get older, said team leader Martha Clare Morris, adding that increasing consumption of green leafy vegetables can offer a very simple, affordable and non-invasive way of potentially protecting your brain from Alzheimer's disease and dementia.

The researchers tracked the diets and cognitive abilities of more than 950 older adults for an average of five years and saw a significant decrease in the rate of cognitive decline for study participants who consumed greater amounts of green leafy vegetables. People who ate one to two servings per day had the cognitive ability of a person 11 years younger than those who consumed none.

When the researchers examined individual nutrients linked with slowing cognitive decline, they found that vitamin K, lutein, folate and beta-carotene were most likely helping to keep the brain healthy.