Study: High-fructose diet sabotages learning, memory

Researchers from the University of California, Los Angeles (UCLA), have demonstrated how a diet steadily high in fructose slows the brain, hampering memory and learning, as well as how omega-3 fatty acids can counteract the disruption.

The study, published in the Journal of Physiology(May 2012, vol. 59:10, pp. 2485-2499), is the first to uncover how the sweetener influences the brain, the researchers noted in a press release.

Its findings illustrate that diet affects how people think, noted Fernando Gomez-Pinilla, a professor of neurosurgery at the David Geffen School of Medicine at UCLA and a professor of integrative biology and physiology in the UCLA College of Letters and Science. A high-fructose diet over the long term affects the brain's ability to learn and remember information, while omega-3 fatty acids can help minimize the damage.

The average American consumes more than 40 pounds of high-fructose corn syrup per year, according to the U.S. Department of Agriculture. The researchers studied two groups of rats that each consumed a fructose solution as drinking water for six weeks. The second group also received omega-3 fatty acids in the form of flaxseed oil and docosahexaenoic acid (DHA), which protects against damage to the synapses.

The animals were fed standard rat chow and trained on a maze twice daily for five days before starting the experimental diet. The UCLA team tested how well the rats were able to navigate the maze, which contained numerous holes but only one exit. The scientists placed visual landmarks in the maze to help the rats learn and remember the way.

Six weeks later, the researchers tested the rats' ability to recall the route and escape the maze.

The group of rats that received the omega-3 fatty acid-enhanced diet navigated the maze much faster than the rats that did not, Gomez-Pinilla said. In addition, the DHA-deprived rats developed signs of resistance to insulin, a hormone that controls blood sugar and regulates synaptic function in the brain. A closer look at the rats' brain tissue suggested that insulin had lost much of its power to influence the brain cells.

The researchers suspect that eating too much fructose could block insulin's ability to regulate how cells use and store sugar for the energy required for processing thoughts and emotions.