Sugary drinks and anxiety in adolescents: a consistent link across multiple studies

One in five young people has a mental health disorder - and diet may be part of the picture

By 2023, estimates suggested that approximately one in five children and young people had a mental health disorder, with anxiety among the most commonly reported conditions. The causes are multiple and interact in ways researchers are still working to disentangle. Diet has emerged as one candidate variable - not as a simple cause-and-effect relationship, but as part of a broader pattern of associations that is becoming difficult to ignore.

Researchers at Bournemouth University, working as part of a team led by Dr. Karim Khaled - now at Lebanese American University in Beirut - have published a systematic review in the Journal of Human Nutrition and Dietetics examining what multiple studies have found when they look at adolescent sugar-sweetened beverage consumption alongside mental health outcomes. The finding that emerges consistently: teens who drink more sugary drinks report higher rates of anxiety symptoms.

What the evidence shows

The review examined studies that measured both dietary patterns and mental health outcomes in adolescent populations through surveys and questionnaires. Beverages counted as sugar-sweetened include fizzy drinks, energy drinks, sweetened fruit juices, squashes, sweetened tea and coffee, and flavored milks. The category is broader than many people assume.

Across the studies examined, the direction of association was consistent: higher consumption of sugar-sweetened beverages correlated with more frequent or more severe anxiety symptoms. The finding held across different populations and different measurement approaches, which gives the association more credibility than any single study could provide.

"With increasing concern about adolescent nutrition, most public health initiatives have emphasised the physical consequences of poor dietary habits, such as obesity and type-2 diabetes," said Dr. Chloe Casey, Lecturer in Nutrition and co-author of the study. "However, the mental health implications of diet have been underexplored by comparison, particularly for drinks that are energy dense but low in nutrients."

The causality problem

The most important caveat in this research is one the authors state plainly: the studies they reviewed establish association, not causation. Three distinct relationships could explain the observed pattern. First, high sugary drink consumption could cause or worsen anxiety through effects on blood sugar regulation, neuroinflammation, or gut microbiome composition. Second, anxiety could drive increased sugary drink consumption, with young people reaching for sweet beverages as a coping mechanism. Third, some external factor could independently drive both - disrupted family environments, sleep disorders, or socioeconomic stress, for example, might increase both anxiety and sugary drink consumption without either causing the other.

"Whilst we may not be able to confirm at this stage what the direct cause is, this study has identified an unhealthy connection between consumption of sugary drinks and anxiety disorders in young people," Dr. Casey said. "Anxiety disorders in adolescence have risen sharply in recent years so it is important to identify lifestyle habits which can be changed to reduce the risk of this trend continuing."

Why this matters for public health strategy

The public health case for reducing adolescent consumption of sugar-sweetened beverages already rests on solid ground - the links to obesity, dental decay, and type 2 diabetes are well-established. If mental health effects are also part of the picture, even as an associated outcome rather than a confirmed causal consequence, that adds another dimension to the case for targeting these beverages in health promotion efforts.

Sugary drinks are also a particularly tractable target for intervention compared to many dietary variables. They are discrete, measurable, and subject to policy levers including taxation, school vending restrictions, and marketing regulation. Several countries have already implemented sugar-sweetened beverage taxes with documented effects on consumption patterns.

Establishing the direction of causality will require longitudinal study designs that track individuals over time, ideally with objective dietary measures rather than self-report. Randomized trials testing dietary interventions in adolescents with elevated anxiety symptoms would provide stronger causal evidence, though they face practical and ethical complexity. In the meantime, the consistent pattern identified in this review is sufficient to inform clinical conversations about diet and mental health with adolescent patients.