Eating more ultra-processed foods may contribute to a person's overall cognitive decline, affecting their ability to process information and make decisions, a new study has found.

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“People who ate more than 20% of daily calories from processed foods had a 28% faster rate of overall cognitive decline and a 25% faster rate of executive function decline compared to people who ate less 20% of processed products,” the co-author of the study and researcher at the Department of Pathology of the Faculty of Medicine of the University of Sao Paulo, Natalia Gonçalves, told CNN.

As an indication, for a person who consumes 2000 calories per day, 20% would be the equivalent of 400 calories. This represents an order of fries with a regular size cheeseburger at McDonald's.

The results were presented Monday at an international conference of the Alzheimer's Association in San Diego. The study followed 10,000 Brazilians for a decade. The average age of the participants was 51 years old. Cognitive tests were performed at the start and end of the study.

"Further studies are needed, but the new findings are quite compelling and underscore the critical role of good nutrition on long-term brain health," said Harvard University neurology professor Rudy Tanzi.

Ultra-processed foods were defined by the researchers as "processed products of food substances (oils, fats, sugars, starch, and protein isolates) that contain little or no whole foods and typically include flavors, colors, emulsifiers and other cosmetic additives'.