Researchers at Brigham and Women’s Hospital, an affiliate of Harvard, looked at the effect of saturated or trans fat – which is found in red meat and butter – on women’s ability to think and remember.
The results have “significant health implications”, according to researchers, since even small declines in cognitive function can increase the risk of developing more serious conditions, such as Alzheimer’s disease and other forms of dementia.
Almost 40,000 women took part in the trial, from which data on 6,000 women over the age of 65 was studied in detail.
They were given three cognitive function test over four years, filling out detailed food questionnaires before each one.
Overall, women whose diet was high in animal products scored worse over the course of the study, while women whose diet was high in “good” monounsaturated fat – which is found in products such as olive oil – scored highest.
“When looking at changes in cognitive function, what we found is that the total amount of fat intake did not really matter, but the type of fat did,” said Olivia Okereke of BWH’s department of psychiatry.
“Substituting good fat in place of the bad fat is a fairly simple dietary modification that could help prevent decline in memory.”