Sugar might be sweet on your palate, but too much of it is a serious health concern. We know that high levels of sugar in the blood have been shown to reduce the working memory capacity of mice, effectively making them more “stupid.” Now a new human-based study done through the Australian National University has shown that even in the high end of the “normal range” blood sugar levels can lead to shrinkage of the brain.
Consumption of refined sugar probably stands at about 60kg per person per year in Australia, that’s a lot of sugar but it does take into account sweeteners used in processed foods and soft drinks. These products contain not only sugar itself (sucrose) but other “sugars” like high fructose corn syrup which is six times sweeter than sugar and is very popular in soft drinks, particularly those manufactured in the United States.
There is a link, of course, between high blood sugar levels and type 2 diabetes. People with diabetes are also at a greater risk of developing dementia and there is a theory that it might be blood sugar levels that are causing this. To investigate whether this might be the case researchers investigated people aged 60 to 64 who had blood sugar levels in the normal range at the start of the study. The normal fasting blood sugar range is 4-6mmol/litre. The subjects had brain scans at the start of the study and then again four years later.
The results showed people with higher fasting levels at the beginning of the study, even if they were still within the normal range, were more likely to have brain shrinkage in the hippocampus and the amygdala. These are the areas of the brain involved in memory and cognitive skills.
After controlling for other factors like high blood pressure, smoking, and alcohol use the researchers were able to establish that fasting blood sugar levels at the high end of the normal range caused between six and ten per cent of brain shrinkage. Therefore even if you don’t have diabetes, blood sugar levels can still significantly impact brain function.