A study published in Scientific Reports, based on longitudinal data from tens of thousands of South Korean adults, has found that increased consumption of sugary carbonated beverages is linked to a higher likelihood of depressive symptoms, irrespective of weight or blood sugar factors. While metabolic issues like obesity and insulin resistance were initially believed to be potential mechanisms, the research indicated that the association persisted even beyond these factors.
“Excessive consumption of added sugars through carbonated drinks is not just a problem in Western society,” said study author Ju Young Jung of the Kangbuk Samsung Hospital at Sungkyunkwan University. “In Asian countries like South Korea, the tendency to drink carbonated drinks instead of water is increasing along with westernization. This can cause a variety of health problems. Obesity and diabetes are just some of them. We investigated the effects of sugar-sweetened carbonated beverage consumption on mental health.”
To conduct the study, the researchers utilized data from the Kangbuk Samsung Health Study, a cohort study that collected medical data from Koreans who underwent medical health check-ups at Kangbuk Samsung Hospital. The study population initially included 136,393 participants who had completed a semi-quantitative food frequency questionnaire — which categorized the frequency and serving sizes of various foods, including sugar-sweetened carbonated beverages — and the Center for Epidemiologic Studies Depression scale.
The participants’ medical history, anthropometric measurements, and laboratory measurements were also collected. This included information on factors like alcohol consumption, smoking, exercise, physical activity levels, education, hypertension, body mass index (BMI), blood pressure (BP), fasting serum glucose, hemoglobin A1c (HbA1c), serum uric acid levels, and insulin resistance (assessed using homeostasis model assessment-insulin resistance or HOMA-IR). These were included as control variables.
The researchers excluded participants with certain medical conditions, those taking specific medications, and those with missing or incomplete data, resulting in a final eligible study population of 87,115 participants. The average age of the study participants was 39.5 years and roughly one-third consumed sugar-sweetened carbonated beverages more than once a week.
Even after account for the control variables, the researchers found a significant positive association between sugar-sweetened carbonated beverage consumption and the risk of depressive symptoms. As sugar-sweetened carbonated beverage consumption increased, the risk of depressive symptoms also increased proportionally.
“Carbonated drinks not only make you fat, but they can also cause another problem: depression. And drinking as little as one can of soda a day can make you feel depressed,” Jung told PsyPost.
“Compared to the United States, Europe, and South America, South Korea is not a country with a high consumption of carbonated beverages. Carbonated beverage consumption per person per day in the United States is known to be over 350ml, whereas in South Korea, it is less than 100ml per day. Therefore, we expected that the association between sugar-sweetened carbonated beverages and depression would not appear well in Koreans. The highest consumption group in our study only consumed more than 5 times a week (1 serving = 200ml). Surprisingly, however, even the group that consumed sugar-sweetened carbonated beverages at least once a week had a higher frequency of depressive symptoms than the group that did not drink at all.”
Several potential mechanisms might be responsible for the link between sugar-sweetened carbonated beverages and depression, including metabolic issues such as obesity, insulin resistance, and diabetes mellitus. However, the researchers noted that the study’s results indicated that the relationship between sugar-sweetened carbonated beverages and the risk of depression wasn’t solely explained by these metabolic factors.
“One of our hypotheses was that insulin resistance or high blood sugar levels could explain the association between sugar-sweetened carbonated beverages and depressive symptoms,” Jung explained. “Therefore, we further analyzed the study by distinguishing the diabetic or prediabetic group from the normal group. However, the association between depression and sugar-sweetened carbonated beverages was confirmed in all diabetes, prediabetes, and normal groups.”
Other potential mechanisms include alterations in gut microbiota, dysregulation of the stress response system, and chronic inflammation. But further research is needed to understand the underlying processes involved.
Jung also noted that “our study did not distinguish between zero-calorie beverages, which have recently been increasing in consumption. It is unclear whether zero-calorie drinks also have a strong association with depressive symptoms in Koreans.”
The study, “Longitudinal analysis for the risk of depression according to the consumption of sugar-sweetened carbonated beverage in non-diabetic and diabetic population“, was authored by Sung Keun Park, Yeongu Chung, Yoosoo Chang, Chang-Mo Oh, Jae-Hong Ryoo, and Ju Young Jung.