Have you ever been nervous about something and felt butterflies in your stomach? Perhaps you've experienced feeling hungry after simply seeing or talking about food?
The gut-brain axis
Although they’re in different parts of the body, our brain and gut are directly linked. They communicate with each other through a number of different mechanisms, including hormones, the release of chemicals, and our autonomic nervous system. As a result, the gut is very sensitive to our emotions; particularly feelings of anger, excitement, anxiety, and sadness. But what about the other way around – how does our gut affect our brain, and ultimately our mood?
The two-way street
After following 1002 people over 12 years, researchers at the University of Newcastle, Australia, found that roughly 50% of participants with long-term symptoms of irritable bowel syndrome (IBS) had experienced anxiety before developing gut issues. IBS is defined as a condition of digestive symptoms, including bloating, abdominal pain, excess wind, diarrhoea, and constipation.
Interestingly, in this study, the other 50% of participants appeared to experience IBS symptoms first, and later developed psychological problems such as anxiety and depression. Such an observation suggests that the health of our gut may directly influence our mood and vice versa.
It’s also been shown that some people who suffer from IBS have mild gut inflammation. As a result, higher levels of cytokines (a by-product of the immune response to inflammation) can be detected in the bloodstream. High anxiety levels can further increase the level of cytokines in the blood, especially in those with pre-existing IBS
Diet and mood
The SMILES (Supporting the Modification of lifestyle in Lowered Emotional States) trial studied 166 people with moderate to severe depression over a 12 week period. Half of the participants were instructed to follow a Mediterranean style diet, while the other half received social support sessions in line with the traditional treatment of depression.
Results of this study showed that participants in the dietary intervention group experienced a much greater reduction in depressive symptoms over the three months. In addition, at the end of the trial, one-third of those in this group met the criteria for remission of major depression, compared to 8% of those who received the social support. In other words, participants who improved their diet the most experienced the most significant improvement in depression.
While there are a few interesting studies on this subject, including the role our gut microbiome may play in communicating with our brain, it’s important to remember this is still an emerging field of research. It does, however, provide an incentive to follow a healthy, balanced diet and be mindful of the impact of stressors in your life.