Scientists have unveiled a significant new link between the regular consumption of soft drinks and an increased risk of major depression, particularly among women. A study published in JAMA Psychiatry examined over 900 adults, with roughly half diagnosed with clinical depression and the other half without, revealing that those who consumed more soft drinks were, on average, 8% more likely to be diagnosed with major depression. The study highlighted that this association was particularly strong in women, with their risk of major depression rising by about 16%, compared to no significant connection among men. Participants self-reported their mental health symptoms and soda intake, with stool samples analyzed to assess gut bacteria.
Dr. Sharmili Edwin Thanarajah of University Hospital Frankfurt explained, “We could really show that soft drink consumption was associated with the diagnosis of depression, but also of symptom severity.” The research suggests that the gut microbiome may play a crucial role in mental health. The study found that higher levels of a gut bacterium called Eggerthella, linked to inflammation and previously associated with depression, were more common among those diagnosed with depression.
Trista Best, a registered dietitian and consultant, noted, “Soda can disrupt gut health by feeding harmful bacteria and reducing the diversity of beneficial microbes, which are essential for digestion and immune balance.” The high sugar and acid content in sodas can also irritate the gut lining, leading to long-term inflammation and bloating. When excessive sugar from soft drinks reaches the gut, it feeds bacteria like Eggerthella, throwing the gut ecosystem out of balance and promoting inflammation that can affect not only the stomach but also the brain, influencing mood and mental health. This imbalance can interfere with the production of serotonin, a neurotransmitter that helps regulate mood.
Further research on mice found that Eggerthella can lower key compounds that support gut and brain health, including tryptophan, which the body uses to produce serotonin. Good gut bacteria, on the other hand, thrive on fiber-rich foods and help produce compounds that reduce inflammation and protect the gut lining. Probiotic supplements may also contribute to improving and stabilizing mood, according to Best.
Soft drinks have long been associated with obesity, diabetes, and heart disease, but their impact on mental health is only beginning to be understood. Previous studies suggest that high sugar intake can trigger inflammation that affects brain chemistry. While the study does not prove a direct causal link between soda and depression, it adds to a growing body of evidence indicating that the gut microbiome plays a significant role in mental health. The sexual differences observed in the study suggest the need for tailored prevention and intervention strategies. Thanarajah acknowledged that soft drinks remain a major source of added sugar globally, with a daily consumption rate particularly high among children and adolescents, which is strongly linked to weight gain, obesity, diabetes, and fatty liver disease. Future studies aim to determine the clinical implications of this connection, as per JAMA Psychiatry. Fox News Digital has reached out to the researchers and the American Beverage Association for comment.