Soft Drinks Linked to Depression Through Gut Microbiota Alterations

A new study found that soft drinks may contribute to depression through gut microbiota alterations involving Eggerthella.1

“While some studies link artificially sweetened beverages to increased depression risk, our data did not show a specific effect on depressive symptoms, likely due to insufficient detail in data collection, warranting further investigation,” study investigator Sharmili Edwin Thanarajah, MD, from the department of psychiatry at University Hospital Frankfurt–Goethe University in Germany, and colleagues wrote.1

Already, research has demonstrated the link between soft drink consumption and negative mental health outcomes. One study reported that women who regularly consume soft drinks are 34% more likely to develop major depressive disorder (MDD) after 4 years.2 However, researchers had yet to fully understand how soft drink consumption relates to MDD or the mechanisms driving this link.

Investigators conducted a multicenter cohort study to examine whether drinking soft drinks was associated with MDD diagnosis and severity.1 The team also sought to assess whether changes in the gut microbiota, particularly Eggerthella and Hungatella abundance, mediated this association. Soft drinks often include additives such as artificial sweeteners (e.g., aspartame, saccharin) and preservatives (e.g., benzoates, sorbates), which may disturb the gut microbiota balance.

This study used cross-sectional data from the Marburg-Münster Affective Cohort, which had recruited patients with MDD (n = 405; 67.9% females; mean age, 36.37 years) and healthy controls (n = 527; 65.5% females, mean age, 35.33 years) aged 18 – 65 years from the general population and primary care settings between September 2014 and September 2018. Data analyses occurred between May and December 2024.1

Primary analyses used multivariable regression and analysis of variance models to assess associations between soft drink consumption and MDD diagnosis or symptom severity, adjusting for site and education. Additional models examined the relationship between MDD and Eggerthella and Hungatella abundance, adjusting for site, education, and library size. Mediation analyses evaluated whether microbiota abundance mediated the association between soft drink intake and MDD.

The study found that soft drink consumption predicted MDD diagnosis (odds ratio [OR], 1.081; 95% confidence interval [CI], 1.008 – 1.159; P =.03) and symptom severity (partial η2 [ηp2], 0.012; 95% CI, 0.004 – 0.035; P <.001). These findings had even stronger effects in women (diagnosis: OR, 1.167; 95% CI, 1.054 – 1.292, P =.003; severity: ηp2, 0.036; 95% CI, 0.011 – 0.062; P <.001).1

Among women, soft drink consumption was associated with increased Eggerthella (P =.007; ηp2, 0.017; 95% CI, 0.0002 – 0.068) but not Hungatella abundance. The mediation analyses further confirmed that Eggerthella significantly mediated the association between soft drinks and MDD (diagnosis: P =.011; severity: P =.005).1

Investigators noted that, despite the small effect sizes, the link between soft drink consumption, Eggerthella abundance, and depression may have clinical implications.

“Given the complex interaction between diet and mental health, it is not surprising that the effect of soft drinks on MDD diagnosis and depressive symptoms is rather small,” investigators wrote.1 “However, it is important to highlight that this is a widely distributed but fully avoidable risk factor.”

Investigators added that incorporating dietary assessments and nutritional counseling into depression prevention and management may help address modifiable lifestyle factors, including soft drink consumption.1 The findings also align with broader public health approaches, such as sugar-sweetened beverage taxation, school sales restrictions, and advertising regulations, aimed at reducing intake. However, most beverage taxes exclude alcoholic and artificially sweetened drinks (with exceptions such as France and Philadelphia, Pennsylvania), which may lead consumers to shift toward these alternatives.

“These findings underscore the role of diet in depression and highlight the gut microbiome as a key mediator,” investigators concluded.1 “The observed sex-specific effects suggest the need for tailored prevention and intervention strategies. Given the global rise in soft drink consumption, public health policies focused on reducing intake through taxation, education, and marketing restrictions are essential.”

References

1. Samuthpongtorn C, Nguyen LH, Okereke OI, et al. Consumption of Ultraprocessed Food and Risk of Depression. JAMA Netw Open. 2023;6(9):e2334770. Published 2023 Sep 5. doi:10.1001/jamanetworkopen.2023.34770

2. Edwin Thanarajah S, Ribeiro AH, Lee J, et al. Soft Drink Consumption and Depression Mediated by Gut Microbiome Alterations. JAMA Psychiatry. Published online September 24, 2025. doi:10.1001/jamapsychiatry.2025.2579