How ultra-processed foods may damage your long-term brain health

July 27, 2026 - 14:46

A growing pile of research now connects ultra-processed foods to a range of mental health issues, including depression, anxiety, and even dementia. Writer Helen Thomson takes a closer look at just how solid the science is behind the idea that a diet packed with these products can damage the brain.

The term ultra-processed foods covers a wide range of items, from sugary sodas and packaged snacks to frozen pizzas and chicken nuggets. These foods are typically stripped of natural fiber and nutrients, then loaded with additives, preservatives, and artificial flavors. While the link to physical problems like obesity and heart disease is well known, the effect on the brain is only now getting serious attention.

Several large-scale studies have found that people who eat the most ultra-processed foods have a significantly higher risk of developing depression. One study followed thousands of middle-aged women for over a decade and found that those with the highest intake of these foods had a 30 percent higher risk of depression compared to those who ate the least. The risk of anxiety also climbed.

The evidence for dementia is more preliminary but still concerning. A recent study of older adults showed that a 10 percent increase in ultra-processed food consumption was linked to a 25 percent faster decline in cognitive function. Researchers suspect that inflammation and damage to blood vessels in the brain play a role. These foods also tend to crowd out healthier options that protect the brain, like fruits, vegetables, and whole grains.

Some experts caution that the studies so far are mostly observational, meaning they show a connection but cannot prove cause and effect. People who eat a lot of junk food may also have other unhealthy habits. Still, the pattern is strong enough that many scientists now recommend limiting ultra-processed foods as a simple way to support both mental and physical health.