Eating large amounts of processed red meat is associated with a higher risk of dementia and cognitive decline, according to research published online in the American Academy of Neurology’s medical journal Neurology.

The research looked at health and nutrition data of 133,771 people with an average age of 49 at the start of the study. Of these, 11,173 were diagnosed with dementia up to 43 years later.

His researchers American health system “Mass General Brigham,” of Harvard’s THChan School of Public Health and the Broad Institute of MIT and Harvard found that those who consumed a quarter or more of a serving of processed red meat daily had a 13% higher risk of dementia compared to those who consumed less than a tenth of a serving every day.

A portion of red meat was defined as approx 85 gramsas much as the size of one bar of soap. As for unprocessed red meat, they compared people who consumed an average of less than half a serving a day with people who consumed one or more servings a day and found no difference in dementia risk.

In addition, the researchers measured objective cognitive function in a different group of 17,458 women with an average age of 74 using standardized cognitive assessments (tests of memory and thinking) and found that cognitive function was worse in those with higher consumption of processed red meat, calculating that cognitive aging is accelerated by about 1.6 years for each additional serving per day.

When they looked at the self-reported subjective cognitive decline (SCD) of 43,966 people with an average age of 78, in which people report problems with memory and thinking before any impairment shows up on tests, they found that the risk of SCD increased by 14% for those who consumed a quarter or more servings of processed meat per day compared to the least consuming group and by 16% for those consuming one or more servings of unprocessed meat per day compared to those who consumed less than half a serving.

Researchers continue to investigate the factors linking red meat to dementia risk, particularly those involving the gut microbiome. They point out that replacing processed red meat with nuts and legumes can reduce the risk of dementia by around 19%, with chicken by 16% and with fish by 28%.