Junk Food Alters Gut & Intelligence

Kathy Wheddon Nutritional Therapist DipION

Researchers at Oregon State University have recently conducted a study1 suggesting that high fat, high sugar diets reduce our mental and emotional ability to ‘adapt and adjust to changing situations’. Laboratory mice were put through a host of tests such as different mazes and puzzles, to test their mental capabilities whilst following different diets with varying levels of fat and sugar. After four weeks, the mice following the high fat, high sugar diet (or the 'junk food' diet) performed significantly worse in all the tests, therefore linking this type of unhealthy diet to lowered brain function.

Gut bacteria could be the link

When considering the reasons why a high fat, high sugar diet could lead to reduced cognitive abilities, the scientists discovered a surprising link. The mice in the high fat, high sugar diet group were found to have significantly altered gut bacteria as compared to the other dietary groups.

microscopic gut bacteria

Increasingly, research is linking brain behaviour back to gut bacteria.

Kathy Magnusson, a professor at Oregon State University said that ‘’this work suggests that fat and sugar are altering your healthy bacterial systems.'' and ''It’s increasingly clear that our gut bacteria, or microbiota, can communicate with the human brain.''

This research supports earlier studies, such as one performed by the ‘Gail and Gerald Oppenheimer Family Center for Neurobiology and Stress’ that linked supplemental probiotics to better cognitive test results and an improved ability to cope with stress.

The science behind how our gut microflora affects our mood and cognitive function is still in its infancy, but it is now understood that our gut bacteria release compounds that act similarly to neurotransmitters, and these have an impact on our brain and emotions.

Additionally, you can read more about how our gut bacteria affects our mood in general, by reading my earlier blog post on ‘Psychobiotics’.

So, it seems that there is yet another good reason to look after our gut flora by limiting sugar and fat and taking a high-quality, well researched probiotic supplement. A healthy gut microbiome could lift our mood and enhance cognitive function, making you happier and more intelligent! Hooray!

For more related reading, see:

Fast food harms gut bacteria, says new experiment

Is your gut bacteria influencing your food cravings?


  1. Magnusson, K. Oregon State University (2015) 'Fat, sugar cause bacterial changes that may relate to loss of cognitive function'. Neuroscience.