Sugar may be as damaging to the brain as intense stress
A team at the University of New South Wales in Australia found sugar is as damaging to the brain as extreme stress or abuse.
Researcher Jayanthi Maniam and profressor of pharmacology, Margaret Morris discuss their findings about sugar and said we all know that cola and lemonade aren’t great for our waistline or our dental health.
They said new study has shed light on just how much damage sugary drinks can also do to our brain. The changes we observed to the region of the brain that controls emotional behaviour and cognitive function were more extensive than those caused by extreme early life stress.
The number of traumatic events accidents, witnessing an injury, bereavement, natural disasters, physical, sexual and emotional abuse, domestic violence and being a victim of crime, a child is exposed to is associated with elevated concentrations of the major stress hormone, cortisol.
There is also evidence that childhood maltreatment is associated with reduced brain volume and that these changes may be linked to anxiety.
Looking at rats, we examined whether the impact of early life stress on the brain was exacerbated by drinking high volumes of sugary drinks after weaning. As females are more likely to experience adverse life events, we studied female Sprague-Dawley rats.
To model early life trauma or abuse, after rats were born half of the litters were exposed to limited nesting material from days two to nine after birth.
At weaning, half the rats were given unlimited to access to low-fat chow and water to drink, while their sisters were given chow, water and a 25 per cent sugar solution that they could choose to drink.
Animals exposed to early life stress were smaller at weaning, but this difference disappeared over time. Rats consuming sugar in both groups (control and stress) ate more calories over the experiment. The rats were followed until they were 15 weeks old, and then their brains were examined.
As we know that early life stress can impact mental health and function, we examined a part of the brain called the hippocampus, which is important for both memory and stress.
Four groups of rats were studied – control (no stress), control rats drinking sugar, rats exposed to stress and rats exposed to stress who drank sugar.
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 rats were exposed to high sugar intakes during development, and the impact of the sugar is worrying as it may affect brain development, although further work is required to test this.
In this study, combining sugar intake and early life stress did not produce further changes in the hippocampus, but whether this remains the case over time is unclear.