Dementia: 25 grams of processed meat per day may raise relative risk
An observational study suggests there is a link between consuming 25 grams (g) of processed meat per day — which amounts to around one rasher of bacon — and a 44% higher risk of dementia.
The study also found an association between eating unprocessed red meats, such as beef, pork, and veal, and reduced risks of all-cause dementia.
A gene variant known as the APOE ε4 allele, which increases a person’s risk of dementia by 3–6 times, did not appear to affect the relationship between diet and the condition.
People with dementia have difficulties with their memory, attention, thinking, and reasoning that interfere with everyday activities. These cognitive difficulties are not part of the typical aging process.
After these adjustments, they found that each additional 25-g portion of processed meat eaten per day was associated with a 44% increase in the risk of dementia from all causes.
This intake was also associated with a 52% increased risk of Alzheimer’s disease.
By contrast, each additional 50-g portion of unprocessed meat eaten per day was linked to a 19% reduction in the risk of all-cause dementia and a 30% reduced risk of Alzheimer’s disease.
The results for unprocessed poultry and total meat consumption were not statistically significant.
Eating large amounts of processed meat was also associated with a higher risk of vascular dementia, but the link with steadily increasing daily consumption was not significant.
As expected, the researchers noted that having the APOE ε4 allele increased the risk of dementia 3–6-fold. However, it did not significantly affect the observed associations between diet and dementia.
A large body of evidence has linked consumption of processed meat to cancer. In 2015, the WHO even went so far as to define it as a carcinogen.
“Worldwide, the prevalence of dementia is increasing, and diet as a modifiable factor could play a role,” says Huifeng Zhang, a Ph.D. student at the School of Food Science and Nutrition at the University of Leeds, who was the lead researcher of the new study.
“Our research adds to the growing body of evidence linking processed meat consumption to increased risk of a range of nontransmissible diseases,” she adds.
It is important to note that the researchers have reported their results as percentage increases in the risk of developing dementia, or “relative risk.”
This is in contrast to the change in “absolute risk,” or how many extra cases there will be per 1,000 individuals, for example.
Ms. Zhang told Medical News Today that data from the UK Biobank are unsuitable for calculating absolute risk, because it is not a representative sample of the entire population.
For example, she said, it does not contain a sufficiently high proportion of individuals aged over 70 years.
The risk of dementia rises with age, so this imbalance would skew any calculation of absolute risk.
It is also worth noting that this was an observational study, so it could not prove that consuming processed meat causes dementia. It does, however, demonstrate a statistical association between the two.
“It’s always important to remember when looking at studies like this that they can’t attribute causation and [that] important confounding factors might account for apparent associations,” says Prof. Robert Howard, professor of old age psychiatry at University College London in the U.K., who was not involved in the study.
“As a doctor who works clinically with people with dementia and conducts research into potential dementia treatments, the data wouldn’t persuade me to give up my breakfast bacon,” he adds.