According to World Health Organization (WHO) estimates, depression is such a common mental health disorder that it affects approximately 5% of all adults worldwide. Countless individuals all over the world suffer from depression, which can severely impair their quality of life. While therapies and medications can help some people manage their symptoms, they are less effective for others. Could diet succeed where other methods have failed?
There are several types of depression, including major depressive disorder and persistent depressive disorder that lasts at least two years. Depression is often caused by a combination of genetic and environmental risk factors — specific stressors or conditions that act as triggers, resulting in recurrent major depressive episodes. While targeted therapy and medication help many people overcome or manage their depression symptoms, these interventions do not work equally well for everyone.
Diet has recently risen to the forefront of medical research, with experts debating the benefits and drawbacks of using dietary interventions to treat or even prevent various medical conditions. Several studies in recent years have suggested that eating a healthier diet rich in vegetables, fruit, and whole grains may help improve depression symptoms. For example, one April 2022 study from the University of Technology Sydney discovered that men aged 18-25 years improved their depression symptoms after switching to a Mediterranean diet. However, it is unknown what mediates the link between diet quality and mental health. Two studies published in Nature Communications in December 2022 investigated the relationship between gut microbiota and depression symptoms.
And this is where diet comes into play: by making certain dietary changes, we may be able to influence the abundance of certain bacterial species in the gut and, as a result, the communication between the gut and the brain, resulting in an improvement in depression symptoms. Dr. Amin is a senior research associate in the Nuffield Department of Population Health at the University of Oxford in the United Kingdom, and one of her research interests is identifying biomarkers of neuropsychiatric traits using genomic data. Dr. Amin and her colleagues analyzed data from 1,133 participants in the Rotterdam study in 2022, asking whether there was a link between the composition of the gut microbiota and experiencing symptoms of depression.
The abundance of certain bacteria, particularly those of the Eggerthella genus, appeared to be linked to an increase in depression symptoms. The researchers explain in their study that these bacteria are involved in the synthesis of certain neurotransmitters, or chemical messengers, the activity of which may be involved in the expression of depression symptoms. Glutamate, butyrate, serotonin, and gamma amino butyric acid are the chemicals involved (GABA). Previous research has suggested that people with depression have higher levels of glutamate in their systems than those who are not depressed, whereas lower-than-usual levels of butyrate have been linked to depression symptoms in people with Parkinson's disease. Lower GABA levels have also been linked to depression.
Why might diet be important? Dr. Amin pointed out that there is only one short step between making the connection between the abundance of certain gut bacteria and symptoms of mood disorders and arguing that diet may also play a role in "feeding" or reducing the expression and severity of depression symptoms. Many substances, such as glutamate and butyrate, are synthesized by gut bacteria from a person's diet, which means that what a person eats will always influence the abundance of those substances in the human body. However, diet influences the abundance of certain bacterial species in the gut, and because some bacteria synthesize certain substances, having too many or too few of some bacterial species can also result in having too much or too little of those substances in our bodies.
Rachel Kelly stated that she felt that increasing the variety of foods in her daily diet was critical to overcoming her depression symptoms. How to Improve Your Diet to Combat Depression? Kelly and Dr. Amin both believe that by taking positive control of one's diet, people can take a step forward in combating the symptoms of depression — or even preventing it entirely. While they both acknowledge that depression is a complex condition with multiple causes, they contend that dietary interventions can be a simple, self-empowering way to improve mental health. Importantly, unlike some of the most commonly used antidepressant medications, such as selective serotonin reuptake inhibitors, a healthy diet does not come with a list of possible side effects. At the same time, Rachel Kelly emphasized that when it comes to combating depression symptoms, diet should only be one of several approaches. She emphasized that there are numerous other things people can do to feel more like themselves.
ZDS DMO II Marie-Claire Gaas, RND
References:
1. In Conversation: Can diet help improve depression symptoms?
By Maria Cohut, Ph.D. on January 31, 2023 — Fact checked by Hilary Guite, FFPH, MRCGP
https://www.medicalnewstoday.com/articles/in-conversation-can-diet-help-improve-depression-symptoms
2. Depression
13 September 2021
