Just 10% more ultra-processed food linked to higher dementia risk

Increasing your daily consumption of ultraprocessed foods by 10% — basically the equivalent of a small bag of potato chips — may raise your risk of dementia even if you normally eat a healthy plant-rich diet, according to a new study.

“Our study showed that UPF consumption was associated with worse attention and higher dementia risk in middle-aged and older adults,” said lead author Barbara Cardoso, a senior lecturer of nutrition dietetics and food at Monash University in Melbourne, Australia.

The study could only show an association, not a direct cause and effect. However, “this association was not changed by adherence to the Mediterranean diet, indicating that this is linked to food processing rather than simply food displacement,” Cardoso said in an email.

The research is an “important addition” to the growing evidence base showing the potential harms of ultraprocessed foods on the brain, said Dr. W. Taylor Kimberly, a professor of neurology at Harvard Medical School in Boston, who was not involved in the study.

Kimberly was the senior author of a similar study published in January that found increasing ultraprocessed food intake by 10% raised the risk of cognitive impairment by 16% even if people ate mostly plants.

“Together these studies highlight that higher UPF consumption is consistently associated with poorer cognitive performance,” Kimberly said in an email.

There is a “silver lining” for people who commit to lowering their UPF intake over the long haul, Kimberly added. His study found replacing UPFs with more minimally processed and whole foods over a five- to six-year period was linked with a 12% lower risk of cognitive decline.

An April study found adults in their 50s and 60s who cut many unhealthy foods from their diet over a decade had an 11% lower risk of Alzheimer’s disease and dementia when compared with adults whose diets didn’t change.

Real versus predigested food

The award-winning Mediterranean diet, which emphasises whole grains, fruits and vegetables, beans, seeds, nuts and extra-virgin olive oil, has been shown to reduce risk for cancer, diabetes, heart disease, stroke and dementia, especially for people with two copies of the APOE4 gene, a key risk factor for Alzheimer’s disease.

Other highly respected plant-rich diets, such as the DASH diet and the MIND diet, also focus on consuming whole foods while limiting sugar, red meat and ultraprocessed foods. They too have been linked to improvements in health — blood pressure, cholesterol, diabetes and overall heart health — all of which can also improve the brain.

Ultraprocessed foods, however, contain little to no whole food. Instead, whole grains and foods are dissembled into molecules which, with the help of artificial colorings, flavorings and gluelike emulsifiers, are heated, pounded, shaped or extruded into any food a manufacturer can dream up.

Such “predigested” foods, which are often full of sugar, salt and fat, may lack critical nutrients needed for a healthy body and brain, experts say.

A 2022 study of 10,000 people found those who ate the most ultraprocessed foods had a 25% faster rate of executive function decline and a 28% faster rate of overall cognitive impairment compared with those who ate the least amount of ultraprocessed food.

Studies on the overall health dangers of eating UPFs are piling up. According to a February 2024 review of 45 studies encompassing some 10 million people, eating 10% more ultraprocessed foods raised the risk of developing or dying from dozens of adverse health conditions.

That 10% increase was considered “baseline,” and adding even more ultraprocessed foods might increase the risk, experts say.

There was strong evidence that a higher intake of ultraprocessed foods was associated with about a 50% higher risk of cardiovascular disease-related death and common mental disorders, according to the review.

Researchers also found highly suggestive evidence that eating more ultraprocessed foods raised the risk of obesity by 55%, sleep disorders by 41%, development of type 2 diabetes by 40% and the risk of depression by 20%.

Attention span and dementia risk

The new study, published in the journal Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, asked more than 2,100 Australians between the ages of 40 and 70 to complete a food diary that captured their diet over the past year. Approximately 42% of the typical Australian diet comes from ultraprocessed foods.

Participants also were asked to undergo cognitive testing to evaluate their ability to pay attention and how quickly they were able to process new information. No one had dementia at the start of the study.

“For every 10 per cent increase in ultra-processed food a person consumed, we saw a distinct and measurable drop in a person’s ability to focus,” Cardoso said via email. “In clinical terms, this translated to consistently lower scores on standardized cognitive tests measuring visual attention and processing speed.”

Attention span is the foundation for many important brain operations, such as learning and problem-solving, the study said. A direct association between UPFs and memory was not found; however, the study did estimate overall mental decline using a validated scoring tool that predicts 20-year dementia risk among middle-aged people.

Each 10% increase in daily UPF consumption was linked to an 0.24 point increase in dementia risk as measured by a scale from 0 to 7 points. Eating ultraprocessed pancakes for breakfast, chips with lunch, a bag of cookies for a snack and a pizza for dinner could quickly add up.

Removing ultraprocessed foods from your diet could reduce risk, especially if done before neurological complications set in, Cardoso said.

“Midlife is a stage that offers a key opportunity to address modifiable risk factors before neuropathological compatible with dementia changes develop,” she said.

“UPFs have been associated with negative changes in the endocrine system and the gut microbiota, and these could lead to negative neurological outcomes,” Cardoso said. “Further, UPFs have been linked to known cardiovascular risk factors for dementia, such as diabetes, hypertension, obesity and high LDL cholesterol, and as such could indirectly impact cognitive health.”

Source: CNN