A growing body of research suggests that ultra-processed foods like frozen pizzas and breakfast cereals high in sugars, fats and empty calories are bad for your health. Now, a new large-scale study presented at the 2022 Alzheimer’s Association International Conference in San Diego this week offers more evidence that people who get a high percentage of their daily calories from ultra-processed foods are also at a higher risk of cognitive decline.

A team of researchers from the University of São Paulo Medical School in Brazil followed a diverse sample of more than 10,000 Brazilians for up to 10 years. The subjects filled out food frequency questionnaires to note how often they were eating foods including: unprocessed or minimally processed ingredients (aka whole foods like fresh, dry or frozen fruits, vegetables, whole grains, meat, fish and milk that underwent minimal processing, like pasteurization); processed foods (canned fruits, artisanal bread and cheese, and salted, smoked or cured meat or fish); and ultra-processed foods (industrial formulations of processed food substances like oils, fats, sugars, starch, artificial flavors and colorings, but containing little or no whole foods). 

The subjects also took cognitive tests up to three times a year, including memory tests and word recognition tests, to monitor their cognitive functioning; aka, mental abilities such as learning, thinking, reasoning, remembering, problem-solving, decision-making and attention. They also took regular verbal fluency tests to track their executive functioning; aka the mental skills that help an individual plan, monitor and successfully meet their goals. 

The findings? Those who ate 20% or more of their daily calories from ultra-processed foods had a 28% faster rate of cognitive decline, and a 25% faster rate of executive function decline, compared to the subjects in the study who ate the least amount of processed foods. In other words, someone following a 2,000-calorie-a-day diet who consumed 400 of their daily calories from ready-to-eat frozen meals, processed meats, breakfast cereals and sugar-sweetened beverages each day saw a faster rate of cognitive decline. 

And many of us are fueling ourselves with these ultra-processed foods. The researchers noted that a whopping 58% of the calories consumed by U.S. citizens come from ultra-processed foods. We’re not alone; 56.8% of the calories consumed by British citizens, 48% of the calories consumed by Canadians, and up to 30% of the calories eaten by Brazilians also typically come from these ultra-processed foods, the researchers added. And despite the rise in plant-based alternatives (some of which are highly processed, themselves) and poultry consumption — and a dip in buying and eating unprocessed red meat — another recent report noted that Americans are still eating as much processed food as they did two decades ago, particularly deli meats, sausage, hot dogs, ham and bacon.