Study links eating lots of ultra-processed foods daily with cognitive decline

Dec. 5 (UPI) -- An association exists between people who obtain a higher percentage of their daily energy from ultra-processed foods and suffering cognitive decline, a large study with long-term follow-up released Monday suggests.

Overall, 58% of the calories consumed in the U.S., 57% of British, 48% of Canadian and 30% of Brazilian diets come from ultra-processed foods, the scientists said.

That includes sweet and savory snacks, confectionery, breakfast cereals, ice cream, sugar-sweetened beverages, processed meats and ready-to-eat frozen meals.

Study participants at the upper end of ultra-processed food consumption -- for whom the daily energy percentage contribution of such foods was above 19.9% -- showed a 28% faster rate of global cognitive decline, and a 25% faster rate of decline in executive function -- the mental skills used every day to learn, work and manage daily life.

That's compared with people who ate no ultra-processed foods or, if they did, stayed below the 19.9% threshold over a follow-up period that averaged eight years.

The findings were published in JAMA Neurology.

While eating ultra-processed foods has been linked to an increased risk of cardiovascular disease, metabolic syndrome and obesity, few studies have investigated the association between such foods and cognitive decline in high-income countries.

So, a team of researchers led by Natalia Gomes Gonçalves, of the Department of Pathology at the University of São Paulo Medical School in São Paulo, Brazil, set about to investigate the association between ultra-processed food consumption and cognitive decline among 10, 775 participants in the Brazilian Longitudinal Study of Adult Health.

The study involved an ethnically diverse sample of public servants, ages 35 to 74, who were recruited in six Brazilian cities.

Food and drink consumption over 12 months was assessed at baseline using a standardized food frequency questionnaire. The frequency of consumption of each item was transformed into grams per day, and then foods were classified, according to the extent of industrial processing used in making them, into one of three food groups.

The first group included unprocessed or minimally processed foods, such as fresh, dry, or frozen fruits or vegetables, grains, meat, fish and milk, which had undergone minimal processing like grinding, roasting, pasteurization or freezing. It also included processed culinary ingredients, such as table sugar, oils and salt.

The second group included processed foods, including canned fruits, artisanal bread and cheese, and salted, smoked or cured meat or fish.

The third group included included ultra-processed foods. The scientists said these are formulations of several ingredients from other food groups, plus food additives not used in home preparation, "such as flavors, colors, sweeteners, emulsifiers and other substances used to disguise undesirable qualities of the final product or imitate the sensorial qualities of culinary preparations" from unprocessed or minimally processed foods.

The scientists looked at participants' cognitive performance over a median follow-up period of eight years, alongside their level of consumption of ultra-processed foods.

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.

The researchers tested people's executive function by using tools including verbal fluency tests.

"These findings support current public health recommendations on limiting ultra-processed food consumption because of their potential harm to cognitive function," the authors concluded.