The dangers of excessive sugar consumption are well known (obesity, diabetes, cavities, powdered sugar everywhere). It is also widely believed that many long-term psychological symptoms (such as anxiety and poor stress management) trace their origins to early childhood trauma. Now, a new study shows that baby rats who were fed sugar soon after weaning showed similar damage to the part of the brain that deals with memory and stress as rats who suffered extreme anxiety at an early age.
The study, published in Frontiers in Molecular Neuroscience, examined four groups of newborn rats, all of which were female: one group that was fed normal food and plain water in a stress-free environment; one group that was fed normal food and supplied with sucrose water in a stress-free environment; one group that endured stress with a regular diet; and one group that endured stress while having access to the sucrose solution.
To model early life trauma or abuse in humans, the researchers created a stressful environment for the rats by giving them only minimal nesting materials in the week after their birth which, as the study's authors noted to The Conversation, “alters maternal behavior and increases anxiety in the offspring later in life.”
When the rats were 15 weeks old, their brains were examined. From The Conversation:
We found that chronic consumption of sugar in rats who were not stressed produced similar changes in the hippocampus as seen in the rats who were stressed but not drinking sugar. Early life stress exposure or sugar drinking led to lower expression of the receptor that binds the major stress hormone cortisol, which may affect the ability to recover from exposure to a stressful situation. Another gene that is important for the growth of nerves, Neurod1, was also reduced by both sugar and stress. Other genes important for the growth of nerves were investigated, and just drinking sugar from a young age was sufficient to reduce them.
The study's authors described the results as of “great concern” and “worrying,” though they added that “further work is required” to know its impact on other animals, including humans. "While it is impossible to perform such studies in humans, the brain circuits controlling stress responses and feeding are conserved across species," they wrote.