These results, observed in participants followed for more than 40 years, once again underline that replacing the proteins in processed red meat with plant proteins (nuts, legumes, fish) can reduce this risk by up to 20%.
One of the authors, Dr. Daniel Wang, of Brigham and Women’s Hospital, a founding member of the Mass General Brigham health system, recalls that: “dietary recommendations tend to focus on reducing the risks of chronic diseases such as heart disease and diabetes, and to neglect cognitive health, which is nevertheless linked to these diseases.”
This observation is essential with the aging of populations and the simultaneous increase in the prevalence of dementia.
The study followed 133,771 participants – from the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS) -, aged on average 49 years at baseline, of whom 11,173 were diagnosed with dementia. Analysis of health data reveals that:
- participants consuming an average of a quarter or more of a daily serving of processed red meat (about two slices of bacon, a slice and a half of bologna, or a hot dog), vs. a minimal amount, had a 13% increased risk of dementia, after taking into account numerous clinical, demographic and lifestyle factors – including family history of dementia;
- these same participants obtain lower scores on cognitive tests;
- their cognitive aging accelerates by approximately 1.6 years per average daily serving of processed meat consumed each day;
- self-reported subjective cognitive decline, a predictive marker of clinical cognitive decline, is also associated with consumption of processed or unprocessed meats (such as beef, pork, and hamburger);
- this risk of self-reported subjective cognitive decline increases by 14% with a quarter or more serving of processed meat per day;
- This risk of self-reported subjective cognitive decline increases by 16% for those who consume 1 to several daily servings of unprocessed meat.
Further research will be conducted into the factors linking red meat to dementia risk, particularly those involving the gut microbiome.
-- The Trimethylamine N-oxide (TMAO)a product of bacterial breakdown of meat, 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 may also harm brain cell health and cerebrovascular health.
Large-scale, long-term cohort studies remain essential to study dementias that can develop over several decades, understand their mechanisms and implement the right interventions.
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