Sugar-high or sugar-low? How does sugary food or drinks affect our emotions?

Sugar rush is a term often used to describe a sudden euphoria and burst of energy after consuming sugary food or drinks. Many people believe that consuming sugar can provide an immediate boost to mood and cognitive performance. Indeed, sweet taste elicits an immediate pleasant feeling as early as infancy (of humans and apes; 1). But is there really a sugar rush beyond tasting the sweetness? The latest meta-analysis (2) found that, across 20 randomized controlled trials^A, there were no effects of sugar on positive emotions on timeframes within or longer than an hour^B. Instead, sugar may bring a crash instead of a rush: higher levels of fatigue and less alertness were seen an hour after the consumption of sugar. Emerging evidence suggests linkages between regular high consumption of sugar and anxiety or depression (e.g., 3). A recent study that followed participants’ depressive symptoms and the sugar intake of thousands of adults for years further suggested that those who had a high intake of sugary food and drinks had an increased risk of developing depression (4). So, excessive sugar is not helpful to our mood^C either in the short term or long term. “Well,” you may say, “but sugar rush does happen in me! I feel happy and energized with sweet snacks and drinks.” Indeed, the above results may not generalize to every single person: there are individual differences in metabolism and sensitivity to sugar. Additionally, in daily life, other factors may have probably contributed to the mood lift that you have experienced: other ingredients in snacks (e.g., cocoa, caffeine), the social presence of others, the sensory pleasure of drinking or chewing, and the fulfilment of expectations. At the end of the day, it is fine to enjoy sugary food or drinks once in a while as part of a balanced diet. However, if your primary goal of sugar intake is mood uplift, for the sake of emotional health, it may be worth considering other ways to achieve this – say, a cup of hot and aromatic floral tea (it works without sugar!), a 5-minute stretching exercise, or a 2-minute pantry chat with colleagues if you’re in the office. Inspire others by commenting below to share YOUR favourite alternative!   This blog was written by Edmund Lo (PhD candidate, Radboud University) for RAD-blog, the blog about smoking, alcohol, drugs and diet. Footnote A: Randomized controlled trial (RCT) is a form of study design that minimizes biases (e.g., participants’ age, gender, preference for sugar, etc). Therefore, one can better infer whether sugar affected emotions with the results from RCT. B: The missing effects after one hour of ingestion are counterevidence to the hypothesis that sugar intake lifts emotions by increasing the availability of serotonin (a neurotransmitter that influences emotions), because it typically takes more than an hour for serotonin levels to change after food intake. C: Not to mention the impact of excessive sugar on physical health: it increases risks of obesity, diabetes, and cardiovascular disease (5). References

1. Steiner, J. E., Glaser, D., Hawilo, M. E., & Berridge, K. C. (2001). Comparative expression of hedonic impact: affective reactions to taste by human infants and other primates. Neuroscience & Biobehavioral Reviews, 25(1), 53-74.
2. Mantantzis, K., Schlaghecken, F., Sünram-Lea, S. I., & Maylor, E. A. (2019). Sugar rush or sugar crash? A meta-analysis of carbohydrate effects on mood. Neuroscience & Biobehavioral Reviews, 101, 45-67.
3. Zhang, X., Huang, X., Xiao, Y., Jing, D., Huang, Y., Chen, L., … & Shen, M. (2019). Daily intake of soft drinks is associated with symptoms of anxiety and depression in Chinese adolescents. Public Health Nutrition, 22(14), 2553-2560.
4. Knüppel, A., Shipley, M. J., Llewellyn, C. H., & Brunner, E. J. (2017). Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study. Scientific reports, 7(1), 1-10.
5. Malik, V. S., Popkin, B. M., Bray, G. A., Després, J. P., & Hu, F. B. (2010). Sugar-sweetened beverages, obesity, type 2 diabetes mellitus, and cardiovascular disease risk. Circulation, 121(11), 1356-1364.