Ultra-processed foods and cognitive decline: unraveling the complex link

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Unhealthy diets, rich in fat and sugar, have long been linked to brain changes and cognitive impairments.

Genetics and socioeconomic factors often contribute to cognitive decline, but research increasingly suggests a poor diet as a risk factor for memory impairments and Alzheimer’s disease.

The role of ultra-processed foods, which are high in sugar, fat, salt, and artificial additives but low in nutrients and fiber, is being examined in this context.

Recent Studies

Two large-scale studies suggest that ultra-processed foods may exacerbate age-related cognitive decline and increase the risk of developing dementia.

On the other hand, another recent study found no association between the consumption of ultra-processed food and worse cognition in people over 60.

Though more research is needed, these preliminary findings underscore the importance of nutrition for brain health.

Detailed Analysis of the Studies

In a December 2022 study involving over 10,000 participants in Brazil, a slightly higher rate of cognitive decline was observed in those consuming more ultra-processed foods at the start of the study.

However, this difference was modest, and it is still unclear if it will have a meaningful effect at an individual level.

The second study involved around 72,000 participants in the UK and examined the link between ultra-processed food consumption and dementia.

Over a 10-year period, the group consuming the highest amounts of ultra-processed foods had a slightly higher rate of dementia diagnosis compared to the group consuming little to no such foods.

Criticism of the NOVA Classification

Research examining the relationship between health and ultra-processed foods often uses the NOVA classification, a system based on the type and extent of industrial food processing.

However, some nutritionists have criticized the NOVA classification for its lack of clear definitions, potentially leading to misclassification.

They argue that the health risks from consuming ultra-processed foods could be more related to the low levels of fiber and nutrients and high levels of fat, sugar, and salt, rather than the amount of processing.

Role of Diet in Brain Health

Despite the uncertainties, healthier diets, like the Mediterranean diet and ketogenic diet, are associated with better cognition in advanced age.

Both diets are rich in plant-based foods and healthy fats, while low in sugars.

They may improve cognitive function by reducing harmful inflammation and influencing the gut-brain axis – the communication between the brain and gut microbiome.

Future Research

Untangling the specific effects of individual foods on the human body is challenging.

Randomized controlled trials, while being the most reliable type of study for establishing causality, are expensive to carry out.

Many nutritional studies, including these two, have only shown correlations between ultra-processed food consumption and health, without ruling out other influencing lifestyle factors.

Lab-based studies using animals, which can control diets and activity levels, will help determine if ultra-processed foods play a key role in cognitive impairments and dementia.

As the world’s population ages and the number of older adults with dementia increases, this knowledge is crucial.

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