How does sugar influence our brain?

Sugar - the sweet 'white gold' that comes in many forms and is now found in almost every food. Sugar makes us feel happy and provides us with readily available energy. But it is also a major cause of many diseases, including diabetes and heart disease. But what is it that makes sugar so irresistible?

Whether in sweets, fruit or even as starch in cereals, sugar seems to be everywhere - and we just can't get enough of it. In fact, per capita consumption of sugar in Germany in 2022/23 was around 33 kilograms, which is about 90 grams of sugar per day [Bundesamt für Landwirtschaft und Ernährung, 2024]. However, according to the World Health Organization, the recommended amount of sugar should be less than 50 grams per day [World Health Organization, 2015].

The influence of dopamine

Eating sugary foods activates our dopaminergic system [Liu & Bohórquez, 2022], which is responsible for motivation and reward in the brain. This leads to the release of dopamine. When we consume sugar, dopamine levels temporarily increase. The dopamine released reinforces the behaviour that led to that reward, such as eating. Dopamine also influences how hard we try to get a reward.

Immediate release of dopamine after eating sugar

A study conducted at the Max Planck Institute for Metabolism Research has shown that dopamine is released immediately after eating sugary foods, even before the food reaches the stomach. Depending on individual cravings, different amounts of dopamine are released at different times. The brains of people with a stronger craving for the high-sugar food released more dopamine immediately after eating, but less once the food had reached the stomach [Thanarajah et al., 2019].

More information about this study can be found here.

Long-lasting changes in the brain

Constant sugar consumption can make us want to eat more and more sugar. A study by the Tittgemeyer research group showed that subjects who ate a high-sugar, high-fat pudding every day for eight weeks reacted more strongly to high-sugar foods than those who ate a pudding with the same number of calories but significantly less fat and sugar. The researchers measured the activity of certain regions of the brain and found that the dopaminergic system was particularly activated in the subjects who ate the pudding with a higher fat and sugar content. The increased sugar consumption altered the neural circuits in such a way that high-sugar foods had a stronger rewarding effect on the subjects, and they rated high-sugar and high-fat foods more positively after the experiment [Thanarajah et al., 2023].

More information about this study can be found here.

References:

• Bundesanstalt für Landschaft und Ernährung (2024). Versorgungsbilanz: Weniger Zucker verbraucht. (Abgerufen am 21.05.2024)
• Liu, W. W., & Bohórquez, D. V. (2022). The neural basis of sugar preference. Nature Reviews Neuroscience, 23(10), 584-595.
• Thanarajah, S. E., Backes, H., DiFeliceantonio, A. G., Albus, K., Cremer, A. L., Hanssen, R., ... & Tittgemeyer, M. (2019). Food intake recruits orosensory and post-ingestive dopaminergic circuits to affect eating desire in humans. Cell Metabolism, 29(3), 695-706.
• Thanarajah, S. E., DiFeliceantonio, A. G., Albus, K., Kuzmanovic, B., Rigoux, L., Iglesias, S., ... & Small, D. M. (2023). Habitual daily intake of a sweet and fatty snack modulates reward processing in humans. Cell metabolism, 35(4), 571-584.
• World Health Organization (2015). Guideline: sugars intake for adults and children. World Health Organization.

This text was written by Lisa Weiher.