The association was observed in a US study. Consuming large amounts of processed red meat increases the risk of dementia by 13 per cent, and subjective cognitive decline by 14 per cent.
Diets rich in processed red meats, such as cold cuts, sausages and hot dogs, are associated with a higher risk of developing dementia. This is what the results of a study by Mass General Brigham, the Harvard T.H. Chan School of Public Health and the Broad Institute of MIT and Harvard in Boston reveal, published in Neurology.
Not only that, the evidence also suggests that replacing processed red meat with other protein sources can, in turn, reduce the risk of dementia.
The researchers examined health data and dietary information from 133,771 Americans starting from an average age of 49; of these, 11,173 received a dementia diagnosis up to 43 years later. As a typical serving of processed red meat, a quantity of 85 grams was considered, equivalent to approximately two slices of bacon, one and a half slices of mortadella or one hot dog.
According to the results, those who consumed, on average per day, a quarter (21 g) or more of a serving of processed red meat had a 13 per cent higher risk of developing dementia compared to those who consumed a minimal amount (less than 8 g per day).
The measurement of objective cognitive function was worse among those who consumed more processed meat, with accelerated cognitive ageing of approximately 1.6 years per average daily serving.
Furthermore, consuming a quarter or more of a serving of processed red meat was also associated with a 14 per cent higher risk of self-reported subjective cognitive decline (which can precede markers of cognitive decline in standard assessments) compared to minimal consumption. This risk increased by 16 per cent for those who ate one or more servings per day of unprocessed meat compared to those who ate less than half a serving.
Replacing one daily serving of processed red meat with nuts and legumes was associated with a 19 per cent lower risk of dementia, 1.37 fewer years of cognitive ageing and a 21 per cent lower risk of subjective cognitive decline.
Researchers are continuing to explore the factors linking red meat to dementia risk, particularly those involving the gut microbiome. One hypothesis is that trimethylamine N-oxide (TMAO), a by-product of bacteria-mediated meat breakdown, may increase cognitive dysfunction due to its effects on the aggregation of amyloid and tau, proteins involved in Alzheimer's disease. The saturated fat and salt content of red meat could also impair the health of brain cells.
"Dietary guidelines tend to focus on reducing the risk of chronic diseases such as heart disease and diabetes, while cognitive health is less frequently discussed, despite being linked to these conditions," said Daniel Wang, one of the study's authors. The researchers hope that the observational findings will encourage greater consideration of the connection between diet and brain health. With an ageing population, dementia represents a growing challenge.