Ultra-processed foods have already been linked by studies to heart disease, metabolic syndrome, obesity and sleep apnea. Now a study published this week in the journal JAMA Neurology adds cognitive decline to the list of potential woes.

Researchers in Brazil followed nearly 11,000 individuals for an average of eight years, finding that limiting how much ultra-processed foods someone eats could help reduce cognitive decline in middle-aged and older adults.

They defined ultra-processed foods as “formulations of processed food substances (oils, fats, sugars, starch and protein isolates) that contain little or no whole foods and typically include flavorings, colorings, emulsifers and other cosmetic additives.”

Their examples include sweet and savory snacks, confections, breakfast cereals, ice cream, sugar-sweetened beverages, processed meats and ready-to-eat frozen meals.

The researchers noted that 58% of calories consumed in the United States come from ultra-processed foods.

Study mechanics

In three waves between 2008 and 2017, a team led by Natalia Gomes Gonçalves of the Department of Pathology at the University of Sao Paulo Medical School tracked public servants ages 34 to 74 who had been recruited in six cities across Brazil. The average age was 51.6 years and slightly more than half were women. Almost 57% had at least a bachelor’s degree.

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They found those in the top quarter of ultra-processed food consumption had a 28% faster rate of global cognitive decline and a 25% faster rate of executive function decline when compared to those in the lowest quarter of ultra-processed food consumption.

The researchers concluded that “a higher percentage of daily energy consumption of ultra-processed foods was associated with cognitive decline among adults from an ethnically diverse sample. These findings support current public health recommendations on limiting ultra-processed food consumption because of their potential to harm cognitive function.”

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The study excluded those who already had cognitive decline or were taking medications that could interfere with cognition, as well as those who regularly consumed less than 600 or more than 6,000 calories a day.

Then the researchers measured cognitive performance over time, using immediate and delayed word recall, word recognition and different fluency tests, among others. Or, as United Press International put it, “People were tested up to three times every four years, testing memory via immediate recall, late recall, and recognition word list tests from the Consortium to Establish a Registry for Alzheimer Disease.”

Other worrisome findings

The Brazilian researchers are far from the first to sound an alarm; international studies have looked at different effects of ultra-processed foods on health.

In just the last few months, three studies have released similar findings, building on other studies:

  • In September, as the Deseret News reported, studies in Italy and the United States said prepping your own meals instead of relying on ultra-processed foods could be important. They linked ultra-processed foods to certain cancers, heart disease and premature death. They also said risk increases with consumption, though both studies noted correlation, not causation.
  • In November, another group of researchers said cutting back on ultra-processed foods could reduce the symptoms from sleep apnea. That research was published in JAMA Network Open.
  • A study in The BMJ journal said adults with the “lowest quality diet” and the most ultra-processed food consumption faced the greatest risk of dying from all causes and also from cardiovascular disease.
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