In a study recently published in the journal Scientific Reports, researchers carried out a longitudinal analysis of data on 87,115 people to investigate the association between the consumption of sugar-sweetened carbonated beverages and the risk of depression.
Their results indicated that beverage consumption was directly and proportionally correlated with the amount and frequency of these beverages. This association was independent of age, sex, and the presence or absence of preexisting diabetes in the study individuals.
SSCB and health
Sugar-sweetened carbonated beverages (SSCBs) are drinks with high concentrations of added sugar. SSCBs have been identified as a prime cause of obesity and have been linked with an increased risk of cardiometabolic diseases.
The negative impacts of SSCBs have been attributed to the large quantities of high-fructose corn syrup and added sugar, which increase serum triglyceride levels and dietary glycemic load, leading to insulin resistance (IR). Cross-sectional epidemiological studies have suggested that metabolic disorders, IR, and depression are linked.
‘Depression’ is an umbrella term for conditions negatively affecting an individual’s mood. It is clinically characterized by feelings of sadness and hopelessness, loss of interest in normal day-to-day activities, and heightened anxiety, all of which cause disruptions in interpersonal relationships and work, school, or social activities.
Depression is a common disorder affecting people of any age, demography, or sex, with an estimated global prevalence of 11-15%. It is a leading cause for increasing trends in disability-adjusted life years, making understanding the factors and mechanisms that contribute to depressive symptoms of critical importance.
Metabolic disorders, including obesity, have been shown to be reciprocally associated with depression. Research has confirmed that individuals with a predisposition for obesity and diabetes have a higher prevalence of depression than those with normal glucose metabolism.
Small-scale cross-sectional studies have attempted to investigate the association between SSCBs and depression. However, these have focused on the combined effects of SSCBs, glycemic status, and IR, with confounding results.
About the study
In the present study, researchers used a longitudinal study approach to investigate the association between SSCB consumption and the risk of developing depressive symptoms. Their analyses were designed to eliminate the confounding impacts of glycemic status and IR, thereby elucidating the independent effects of SSBCs.
This is the first study to measure ranges of SSBC consumption to evaluate changes in depression risk with the quantity and frequency of SSBCs consumed.
Researchers derived their clinical and echocardiographic data from the Kangbuk Samsung Health Study (KSHS), a repository of information on Korean patients who received treatment from the Kangbuk Samsung Hospital.
Researchers first included data from 136,393 working Koreans but then excluded individuals with preexisting mental health conditions and those with severe medical ailments (cancer, stroke, coronary heart disease). The remaining 87,115 individuals were included in the study between March 2011 and December 2012, with follow-up studies conducted for 5.9 years after.
Clinical and biochemical data was collected from hospital records supplemented with a health-related behavior questionnaire. The questionnaire recorded subjects’ physical activity levels via the International Physical Activity Questionnaire (IPAQ), their health behaviors (smoking, alcohol consumption), and educational status.
Fasting blood glucose was recorded at each follow-up session to evaluate subjects’ glycemic status, which researchers classified into normal glycemia, prediabetes, and diabetes mellitus (DM). This classification was based on the homeostasis model assessment-insulin resistance (HOMA-IR) model.
A semi-quantitative food frequency questionnaire (FFQ) was used to evaluate and classify subjects’ SSCB consumption, both in terms of quantity (expressed in serving sizes where one serving = 200 mL) and frequency (per week).
Subjects were categorized into five groups depending on SSCB consumption. The groups were: never/almost never; < 1 serving/week; 1 ≤ ~ < 3 serving/week; 3 ≤ ~ < 5 serving/week; and ≥ 5 serving/week).
The Center for Epidemiologic Studies Depression (CES-D) questionnaire was used to evaluate depressive symptoms per week. The questionnaire comprised 20 questions about negative/depressive feelings, with answers ranging from 0 (seldom/never) to 3 (5-7 days a week). If the total score from the CES-D questionaries was 16 or higher, the individual was classified as having depressive symptoms.
Statistical analyses involved using linear regression models to analyze continuous variables and the Cochran-Armitage trend test was used to measure categorical variables. A Cox proportional hazards model was used to adjust results for multiple covariates, including age, sex, physical activity, BMI, alcohol intake, smoking, marital status, total calorie intake, hypertension, and HOMA-IR.
The study cohort included individuals between 32 and 46 years (mean 39.5), 64.2% (55,941) of whom were male. Results revealed that 28.9% (25,246) of individuals had SSCB intakes higher than one serving per week. Of these, individuals consuming more than five servings per week depicted more elevated fasting glucose, HOMA-IR, BMI, alcohol consumption, smoking, total calorie intake, education, and hypertension prevalence than other groups.
Over almost six years of follow-up, 14.9% of participants developed depressive symptoms, predominantly from high SSCB intake groups. Statistical analyses adjusted from covariates revealed a repeating trend of proportionally increasing risk of DM with increasing SSCB consumption.
These results were mirrored across sex, BMI, and glycemic status, implying that SSCBs play an independent role in triggering depression, and are not just cofactors in the condition along with IR and obesity as previously suggested.
Results from this study support previous cross-sectional studies, which also found an association (sometimes as high as 60%) between SSCB and depression. However, those studies failed to investigate the role of SSCBs in isolation and did not employ a dose-dependent study design.
The present study is hence able to suggest plausible mechanisms of SSCB action and support further that SSCBs increase depression risk independent of preexisting metabolic derangements.
A potential explanation for these findings may be the detrimental effect of elements rich in SSCB on neurobiological [systems]. SSCB contains large [amounts] of sugar and fructose corn syrup. Laboratory evidence from rat [models] showed that high consumption of fructose during preadolescence showed increased anxiety-like behavior and depressive-like behavior in their adulthood.
Park et al. (2023)
Diets including fat and high fructose corn syrup have been shown to radically alter gut microbiota compositions, which in turn contribute to negative alterations in ventral striatal functions underlying neurobehavioral impairment.
These alternations begin at and are more prominent in young and preadult individuals, suggesting that abstinence from SSCBs in youth may help prevent future depressive symptoms.
In the present study, researchers conducted a longitudinal survey of 87,115 working Korean adults to investigate the dose-dependent association between sugar-sweetened carbonated beverages and the risk of depressive symptoms. Their results indicated that the risk of depressive symptoms increases proportionally with SSCB consumption, a trend most prominent in younger individuals.
These findings were able to delink the role of SSCB in depression from the hitherto pooled impacts of glycemic status, IR, and SSBCs. This identifies SSCBs as an independent factor in depression risk. Analyses elucidate that the effects of SSCBs are not dependent on sex, glycemic status, or DM but suggest that younger individuals might be at heightened risk from SSCB consumption than older individuals, given the gut microbial alterations that SSCBs induce and their effects on neurobehavioral impairment.
Our results may be additional evidence for the harmfulness of SSCB, supporting the policy or social campaign to limit marketing of SSCB.
Park et al. (2023)