New Delhi: Bingeing on salty snacks isn’t just a threat to the waistline; it could also be weighing down moods. A new study conducted in China found that a high-salt diet triggered depression-like behaviour in mice, building on existing research that warns against excessive sodium intake.
The peer-reviewed study ‘High-salt diet drives depression-like behavior in mice by inducing IL-17A production’ was published in The Journal of Immunology on 22 March.
“We hope these findings encourage discussions on salt consumption guidelines,” said Dr. Xiaojun Chen, who led the study, Technology Networks reported.
While previous studies have shown that a high-salt diet can lead to bacterial infection, heart disease, and autoimmune disorders, researchers at Nanjing Medical University, China, have gone a step further, linking excessive salt intake to a negative impact on the brain. This, they said, leads to depression-like behaviour.
“Major depression disorder (MDD) is a mental health disorder caused by multiple factors and is a major cause of suicide. Major depression is also associated with increased vulnerability to other diseases such as infectious diseases, autoimmune diseases, and cancer,” wrote the researchers in the study.
The study follows a September 2024 study by scientists from Hong Kong that established a link between fast-food intake and symptoms of depression and anxiety in young adults. “The frequent intake of high-fat, -sugar, and -sodium fast foods increased depressive symptoms, while frequent high-fat fast-food intake was associated with anxiety symptoms,” observed the scientists in the study.
In India, the government has also recognised the need for dietary reforms. Through the Food Safety and Standards Authority of India (FSSAI), in 2018, it launched the Eat Right India campaign, with the aim to promote safe, healthy, and sustainable food choices. As part of its long-term vision for 2050, the initiative focuses on reducing excessive salt, sugar, and oil consumption.
What the study said
Scientists at the Nanjing Medical University used female mice aged between 8 and 12 weeks to test the impact of a high-salt diet.
Mice and rats are generally used for biomedical research because they are genetically similar to humans.
In this study, mice were housed in controlled temperatures at a pathogen and rodent-free facility. This experimental group was fed a high-salt diet, which was maintained for a period of 5 to 8 weeks to better analyse the impact.
The mice were then put under chronic stress to mimic the effects of prolonged psychological strain on depression in humans. This was done by placing them in 50ml centrifuge tubes with tiny breathing holes, restricting their movement for 4 hours each day over a period of three weeks.
The researchers used Open-field tests (OFTs) and mazes to test anxiety-like behaviour in mice who were on the high-salt diet. These mice were kept in a 50 cm x 50 cm x 50 cm box and were allowed to move freely for 5 minutes.
Analysing the movement of the mice the researchers inferred, “More time spent in the edges of the box with less time spent in the center of the box is interpreted as anxiety-like behaviour.”
Another experiment was the forced swim test, designed to evaluate the behaviour of despair. In this test, mice were placed in a glass tank filled with 20 cm of water, positioned in a way that they had no option but to swim.
Over the six-minute period, researchers closely monitored the mice, measuring the time they remained motionless. Mice on the high-salt diet exhibited prolonged immobility in the tank, where they stopped struggling to swim and simply floated—which researchers say are clear signs of behavioural despair.
On the basis of these experiments, researchers observed that a high-salt diet disrupts cellular metabolism, leading to increased production of IL-17A, a pro-inflammatory molecule, responsible for the depression-like symptoms.
“Our findings suggest that the dietary salt restriction may be a promising intervention strategy for depression,” the researchers emphasised.
Sneha Yadav is an intern with ThePrint.
(Edited by Sanya Mathur)
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