A new animal study suggests that diets low in fiber, commonly associated with highly processed foods, may contribute to memory decline in the aging brain. Researchers found that the amygdala, a small but critical brain structure involved in emotional memory (especially fear-related experiences), appears particularly vulnerable.
While the research was conducted in rats, the findings raise important questions about how modern diets may influence brain aging, cognition, and emotional regulation in humans.
The aging brain and the role of fiber
Dietary fiber is often discussed in the context of gut health and metabolism. However, fiber also plays a crucial role in the gut-brain axis, the communication network linking digestive health and neurological function.
When fiber intake is sufficient, beneficial gut bacteria produce short-chain fatty acids (SCFAs) such as butyrate. These compounds help regulate inflammation, support the blood-brain barrier, and may influence neurotransmitter balance.
In the recent study, aged rats fed a low-fiber diet showed signs of impaired memory performance, suggesting that inadequate fiber intake may accelerate certain aspects of cognitive aging.
Amygdala: a brain region sensitive to processed foods
The amygdala is responsible for processing emotional memories, particularly those linked to fear, stress, and negative experiences. It plays a key role in survival instincts and behavioral responses.
Researchers observed that low-fiber diets appeared to affect gene expression and inflammatory markers in the amygdala of aged rats. This suggests that highly processed, fiber-deficient foods may create a biological environment that makes emotional memory circuits more vulnerable over time.
Although human data are still needed, the findings reinforce concerns that highly processed diets may influence not only physical health, but also emotional and cognitive resilience.
Fiber, inflammation, and cognitive aging
One possible explanation lies in inflammation. Diets low in fiber are often associated with increased systemic inflammation and altered gut microbiota composition. Chronic inflammation has long been linked to neurodegeneration and age-related memory decline.
As we age, the brain becomes more sensitive to inflammatory stress. A diet lacking fiber may amplify this vulnerability, particularly in regions like the amygdala that are closely involved in stress and emotional processing.
Importantly, this does not mean fiber alone prevents cognitive decline. However, it may represent one modifiable dietary factor that contributes to brain health longevity.
