December 13, 2021

How Diet Affects Mental Health

Katie Johansen

We often consider our physical health as a result of our diet, but what about our mental health? It turns out what we eat actually has a strong effect on our mental state. Unfortunately, our culture has not helped promote positive norms that support a healthy, balanced diet. Here's how diet affect mental health, and how we can change our relationship to food to promote positive mental health.

The Science Behind It

Our diet has a direct effect on our brain. Research has found that diets high in saturated fats and refined sugars weaken the brain’s ability to function properly and efficiently. Put simply, this is because the brain depends on the nutrients from our diet to “feed” the brain. Certain foods, like fruits, vegetables, and whole grains are high in vitamins and antioxidants that the brain needs to stay nourished. Conversely, highly processed foods and refined sugars contain chemicals that can enter the brain and disrupt the functioning of your brain, and ultimately negatively affect our mental states.  

Another way in which diet affects mental health is through the gut. Gut health has a major implication on mental health, mainly because of the gut microbiome. The gut microbiome, which is heavily influenced by diet, interacts with the brain and in turns affect one’s mental state. Furthermore, the gut produces the majority of the body’s neurotransmitter serotonin, which is directly related to mental disorders such as depression and anxiety. Again, research has found that diets high in processed foods and refined sugars lead to poor gut health, and often poor mental health.

The Culture Behind It  

Although the scientific evidence is important, equally as important is the role of culture. Our culture has some extremely unhealthy norms about diet and eating behaviors, particularly for women. Our culture tends to view a “healthy” diet as one that produces the ideal body type, as opposed to one that makes us feel good physically and mentally. These unhealthy standards and norms about diet are a major source of poor mental health that manifest in eating disorders, depression, anxiety, and other mental illness. Working to reverse these unhealthy thought patterns will promote positive mental health. There is great power in viewing our diet as a means to improve our physical and mental health, rather than simply our physical appearance.  

Ultimately, diet does have a major effect on mental health, and can be used as a means to improve our mental state. However, it is most important to remember that there is not one proper diet that everyone should follow. We all have individual differences and certain foods may work for some and not for others. The best way to start thinking of our diet as part of our mental well-being is to listen to your body--if you listen it will tell you what foods make you feel good and help nourish the brain.


Selhub, E. (2020). Nutritional Pyschiatry: Your Brain on Food. Harvard Health Publishing.

Firth, J., Gangswisch, J. E., Borsini, A., Wooton, R. E., & Mayer, E. A. (2020). Food and mood: how do diet and nutrition affect mental wellbeing? BMJ, doi:

Image Credit: Flickr-Ars Electronica

Katie Johansen is a psychology intern at Thaddeus Resource Center. In December 2021, Katie will be graduating from Cal Poly, San Luis Obispo with an undergraduate degree in psychology. Katie is passionate about mental health and working with underserved community members, and hopes to pursue her master's degree in clinical psychology in the near future.