Eating just two slices of deli meat a day could raise your risk of dementia, a major new study suggests.
Researchers across 26 institutions combed through studies of more than 500,000 people to examine the effects of ultra-processed foods on how the brain ages.
In their review, the team found that each additional 25g of processed meat – such as deli meat, bacon and hot dogs – per day was associated with a 44 to 52 percent increased risk of dementia.
Twenty-five grams is the equivalent of two slices of deli turkey, one strip of bacon or about half a hot dog.
‘A lot of people inside and outside of science are worried about the effects that food processing and artificial food additives might have on health, but it is hard to know what reported health effects are real and which ones are not,’ Dr Owen Carmichael, study author and Director of Biomedical Imaging at Louisiana State University’s Pennington Biomedical Research Center, said.
‘This review gives us an opportunity to step back and look at all the evidence we know of that suggests that ultra-processed foods could affect the brain.
‘The bottom line is that some of the data is concerning, but there are still many unanswered questions about how these relationships work and what they mean for long-term cognitive health.’
It’s unclear exactly how preservatives added to meats during processing, such as nitrates, damage the brain, but experts believe they can trigger harmful inflammation and blood vessel damage that may undermine the connections responsible for memory.
Just two slices of deli meat per day may be associated with a higher risk of dementia, a new study suggests
Meanwhile, foods rich in antioxidants and omega-3 fatty acids – such as berries, salmon and avocado – have been shown to lower inflammation and preserve the structure and function of brain cells.
Researchers in the new review cautioned that the findings showed an association but did not prove that eating processed meat causes dementia. They said that more studies were needed.
‘Following recommendations that discourage [ultra-processed food] consumption at individual and population levels appears to be promising for promoting better brain health late in life,’ the researchers wrote.
The findings come as more than 70 percent of the US food supply is considered ultra-processed, meaning it is mostly made from industrial ingredients and preservatives rather than whole foods.
There are also seven million Americans living with dementia, a number that is expected to double by 2050.
Deli meat has been tied to a range of health consequences, including colon cancer. Experts believe this is because preservatives such as nitrates are converted into carcinogens in the body, which damage healthy cells.
The Dietary Guidelines for Americans recommend ‘significantly limiting highly processed foods,’ such as deli meats.
In the new review, published in the Annual Review of Nutrition, researchers looked at more than 170 studies that tracked the dietary habits and long-term health of over 500,000 people.
The review included studies evaluating the effect of diet on brain health and cognitive decline in both humans and animals.
The researchers found that, overall, people who consumed higher amounts of ultra-processed foods were at a higher risk of developing dementia.
Studies cited by the researchers included a paper involving more than 10,000 adults in Brazil, which found that over the course of eight years, people who consumed more than 20 percent of their daily calories from ultra-processed foods suffered from faster declines in memory and reasoning skills.
However, this effect showed up only in people who did not closely follow the MIND diet, a version of the Mediterranean diet that emphasizes berries, leafy greens, nuts, fatty fish, beans and legumes.
The team also evaluated the effect of reducing ultra-processed food consumption.
In one cited analysis using data from the UK Biobank database, mathematical modeling showed replacing 10 percent of calories from ultra-processed foods with unprocessed foods was associated with a 19 percent lower risk of dementia.
Additionally, researchers cited pooled data across multiple reviews that found people with higher ultra-processed food intake had between 22 to 53 percent higher chance of developing depression or anxiety symptoms.
Those studies revealed that brain scans linked to higher intake of fat, sugary drinks, meat and processed meat showed smaller brain volume, potentially causing damage to the brain’s mood and memory centers.
The researchers noted that a challenge in their review is separating the effects of preservatives from processing itself from added fat, sugar and salt also found in these foods.
They called for additional studies to look more closely at this relationship and said that while lowering processed meat consumption may lower dementia risk, it is not a proven prevention strategy.
