New research has found that consuming ultra-processed foods – including cured meats, sugary drinks and fast food – for more than a fifth of your daily calorie intake could have a negative impact on cognitive function.

Ultra-processed foods see original produce significantly altered, with sugar, fat and salt often added. In the UK, 56.8 per cent of average daily calories come from such foods, including crisps, biscuits and chocolate.

Research has long since linked eating highly processed foods with increased risks of cancer, diabetes, obesity and cardiac disease but the latest study by University of São Paulo Medical School suggests that if 20 per cent or more of your daily diet is made up of junk food, cognitive function could also be impacted.

The research, which was presented at the 2022 Alzheimer’s Association International Conference in San Diego, asked 10,000 Brazilians, with an average age of 51, to record their eating habits for up to a decade. Researchers then looked at the results of cognitive tests – including immediate and delayed word recall, word recognition and verbal fluency – in relation to the participants’ daily diet.

The study found that men and women who ate the most ultra-processed foods saw their global cognitive function decline 28 per cent faster than those who ate a diet of non-processed food. The same group had a 25% faster rate of executive function decline compared with people who avoided processed foods in their diet.

Rudy Tanzi, professor of neurology at Harvard Medical School and director of the genetics and aging research unit at Massachusetts General Hospital in Boston, said of the study: “While in need of further study and replication, the new results are quite compelling and emphasize the critical role for proper nutrition in preserving and promoting brain health and reducing risk for brain diseases as we get older.”

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He added that ultra-processed foods “are usually very high in sugar, salt and fat, all of which promote systemic inflammation, perhaps the most major threat to healthy aging in the body and brain.

“Meanwhile, since they are convenient as a quick meal, they also replace eating food that is high in plant fiber that is important for maintaining the health and balance of the trillions of bacteria in your gut microbiome, which is particularly important for brain health and reducing risk of age-related brain diseases like Alzheimer’s disease.”

The study’s co-author, Dr. Claudia Suemoto, an assistant professor in the division of geriatrics at the University of São Paulo Medical School, said diets in the western world relied on ultra-processed foods too heavily, saying: “Fifty-eight percent of the calories consumed by United States citizens, 56.8% of the calories consumed by British citizens, and 48% of the calories consumed by Canadians come from ultra-processed foods.”

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

In June, The College of Medicine’s Chair, Dr Michael Dixon, told the Food on Prescription conference in London that the UK Government’s new food strategy paper, published on June 13th, fell ‘far short’ of what it required to improve the health of the nation – calling for a tax on foods high in sugar and salt.

Dr Dixon said the paper didn’t go far enough in addressing issues that will help reduce preventable disease and the burden on our healthcare system.

He told attendees: “The College of Medicine believes that a National Food Strategy should ensure that healthy eating is affordable and available for everyone  – enabling and supporting all of us to live as healthy lives  as possible in line with the  values of the NHS. The current strategy published today falls far short of these aspirations.

“Changing things radically will require comprehensive cultural change at a local level – it is a pity that this paper leaves out that part of Henry Dimbleby’s strategy.

“Nothing else has been shown to work, eg the five-a-day campaign made little difference, but we know Government restrictions, for example curbing smoking, can work. Why not restrict sugar and salt, which carry equally harmful effects and economic consequences? Is this a Government that cares about those who most need to eat a healthy diet?”