A recent study published in The Journal of Immunology reveals that a high-salt diet (HSD) triggers depression-like symptoms in mice. Researchers found that HSD boosts the production of a protein called IL-17A, which has been previously linked to depression in human studies.
Dr. Xiaojun Chen, a researcher at Nanjing Medical University and the study’s lead author, emphasized the importance of dietary changes as a preventive measure for mental health issues. “This work supports salt reduction as a strategy to prevent mental illness. It also opens the door for new treatments targeting IL-17A to combat depression,” Dr. Chen said. She added that the findings could spark conversations around revising salt consumption guidelines.
Key Immune Cells Play a Role
The study also discovered that a specific immune cell, gamma-delta T cells (γδT cells), contributes significantly to the production of IL-17A in mice consuming a high-salt diet. These cells were responsible for approximately 40% of IL-17A production. When researchers depleted these cells, the mice showed a notable reduction in depression-like symptoms, suggesting a potential avenue for new treatments.
Widespread Issue of High-Salt Intake
High-salt intake is common in the Western diet, particularly in fast foods, which often contain up to 100 times more salt than homemade meals. This excessive salt consumption is already linked to cardiovascular, autoimmune, and neurodivergent diseases. In addition, major depression disorder (MDD), which affects 15-18% of people over a lifetime, is one of the top 10 causes of death in the U.S.
Although high-salt diets have long been connected to depression, the exact mechanisms behind this link were previously unclear. This new study sheds light on how high-salt diets contribute to depression development.
Experimental Findings
In the study, mice were fed either a normal diet or a high-salt diet for five weeks, a common period for testing the effects of excessive salt intake. After five weeks, the mice on the high-salt diet showed less interest in exploring and demonstrated more inactivity, behaviors commonly associated with depression.
Building on the known role of IL-17A in depression, the researchers measured IL-17A levels in the mice. They found that HSD increased IL-17A in the spleen, blood, and brain, correlating with symptoms of anxiety and depression. When mice unable to produce IL-17A were fed a high-salt diet, they did not exhibit depression-like behaviors, confirming that IL-17A plays a key role in the development of these symptoms.
Implications for Future Research and Treatment
These findings support existing epidemiological data that shows a strong correlation between high-salt intake and more severe depression. The study also aligns with research showing that lower sodium intake is linked to improved mood.
Dr. Chen and her team are now focused on expanding these findings to human studies. They plan to further investigate how high-salt diets activate γδT17 cells, leading to increased IL-17A production, which in turn contributes to depression-like symptoms. The team hopes their work will inspire new therapies aimed at regulating IL-17A or targeting γδT cells as potential treatments for depression.
Related topics: