The study published in the Journal of Affective Disorders by researchers at Tianjin Medical University claimed that a link may exist due to sugar content in carbonated soft drinks, but warned that more research was required.
Cohort analysis
Under the study, the researchers analysed data from 3,667 participants who gave information on eating habits and emotional state as part of the Tianjin Chronic Low-grade Systemic Inflammation and Health Cohort Study. The mean age for the cohort was 42.5 years old.
7.6% of the cohort was classed as having severe to moderate depression. Depressive symptoms were assessed by the Chinese version of the Zung Self-Rating Depression Scale, whereby participants were asked to grade 20 items positively or negatively.
“The prevalence of depressive symptoms was doubled for participants who consumed over four cups of soft drink compared to those who consumed one cup a week,” said the study.
Soft drink consumption was found to be very low in comparison to Western Countries such as the US for example. Only 5% of Chinese participants in the cohort study consumed over four cups of soft drink a week, but the odds were higher for these people to report depressive symptoms.
Are the Chinese more susceptible?
The researchers said the odds were even higher for Chinese people in this cohort study than in previous studies of consumers in Western countries.
“This might be partially because the total consumption of sugar in China is relatively low comparing to the Western countries, which make the high sugar-contained soft drinks have a bigger impact on the mental health of Chinese individuals.”
The researchers said that traditional Chinese beverages such as green tea were often consumed without added sugar, unlike coffee and black tea in the Western world.
They acknowledged that unhealthy eating habits could be responsible, but even when they excluded those with high and low energy intakes there was still a correlation between soft drink consumption and depression.
Link to sugar
The authors claimed the link could be related to the sugar content.
“One possible biological explanation for the connection between soft drinks and depressive symptoms might be related to endothelia dysfunction or low-grade inflammation induced by sugar.”
The researchers said that any relation between sugar and fat and depression was still unclear, although some studies have indicated an association with sugar.
According to earlier research, soft drinks are the main source of added sugars and account for 7% of total energy intake in the American diet.
The study authors added that caffeine could be a possible culprit, but said further research was needed.
They said theirs was the first study to assess the relationship between soft drink consumption and depression among the Asian population.
Source:
Journal of Affective Disorders 172 (2015) 422–427
http://dx.doi.org/10.1016/j.jad.2014.10.026
‘Soft drink consumption is associated with depressive symptoms among adults in China’
Authors: Bin Yu et al.