A rat study has shown how a diet high in fructose (from corn syrup, not the natural levels that occur in fruit) impairs brain connections and hurts memory and learning — and how omega-3 fatty acids can reduce the damage.
We know that these unnaturally high levels of fructose can hurt the brain indirectly through their role in diabetes and obesity, but this new study demonstrates that it also damages the brain directly.
In the study, two groups of rats consumed a fructose solution as drinking water for six weeks. One of these groups also received omega-3 fatty acids in the form of flaxseed oil and DHA. Both groups trained on a maze twice daily for five days before starting the experimental diet. After the six weeks of the diet, the rats were put in the maze again.
Those who didn’t receive the omega-3 oils navigated the maze much more slowly than the second group, and their brains showed a decline in synaptic activity. They also showed signs of resistance to insulin. Indications were that insulin had lost much of its power to regulate synaptic function.
It’s suggested that too much fructose could block insulin's ability to regulate how cells use and store sugar for the energy required for processing information.
It’s estimated that the average American consumes more than 40 pounds of high-fructose corn syrup per year.
The findings are consistent with research showing an association between metabolic syndrome and poorer cognitive function, and help explain the mechanism. They also support the consumption of omega-3 fatty acids as a preventative or ameliorative strategy.
 . ‘Metabolic Syndrome' in the Brain: Deficiency in Omega-3 Fatty Acid Exacerbates Dysfunctions in Insulin Receptor Signalling and Cognition. The Journal of Physiology [Internet]. 2012 ;590(10):2485 - 2499. Available from: http://jp.physoc.org/content/590/10/2485