A new study has found that a diet high in one thing could be linked to depression after being found to trigger the condition in mice. The study in The Journal of Immunology found that a high-salt diet induces depression-like symptoms in mice by driving the production of a protein called IL 17A.
This protein has previously been identified as a contributor to depression in humans.
“This work supports dietary interventions, such as salt reduction, as a preventive measure for mental illness. It also paves the way for novel therapeutic strategies targeting IL-17A to treat depression,” said Dr Xiaojun Chen, a researcher at Nanjing Medical University who led the study. “We hope these findings encourage discussions on salt consumption guidelines,” said Dr Chen.
High-salt intake is ubiquitous in the Western diet, with fast foods often containing 100 times more salt than a home-cooked meal. Salt is already a public health concern as it is linked to cardiovascular, autoimmune, and neurodivergent diseases. Major depression disorder is also a significant public health concern with a lifetime prevalence of 15-18% and a place in the top 10 causes of death.
In this study, mice were fed a normal diet or high-salt diet for 5 weeks. After five weeks, the mice fed salt showed less interest in exploring and more inactivity in various scenarios compared to mice fed a normal diet, suggesting depression-like symptoms.
The high-salt diet increased depression-linked protein levels in the spleen, blood, and brain, correlating with anxiety - and depression-like behaviors. However, when mice that could not produce IL-17A were fed an HSD, depression-like symptoms were not observed, confirming the role of IL-17A in developing depression-like symptoms.
These findings corroborate evidence that a high ssat diet correlates strongly with more severe depression and studies in people demonstrating that low sodium intake is closely associated with good mood.
The researchers hope these findings encourage further research into immune-mediated mechanisms of depression and pave the way for novel treatments. Dr. Chen and their team plan to validate the findings in humans.