Eating two portions of mushrooms per week could halve your risk of abnormal brain decline in old age.
Researchers found people who eat 300g or more of cooked mushrooms – about equal to a medium-sized punnet – have a reduced risk of mild cognitive impairment.
And even eating smaller amounts could still be beneficial, they said.
MCI is between natural brain decline and dementia, and people with the condition may experience forgetfulness and reduced language and attention skills.
Mushrooms contain an amino acid which the body can't make for itself and which is found in particularly low levels in people with MCI, scientists said.