UCLA Study Finds Sugar and High Fructose Corn Syrup Can Hamper Learning

“Our find­ings illus­trate that what you eat affects how you think,” said 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. “Eating a high-fructose diet over the long term alters your brain’s abil­ity to learn and remem­ber infor­ma­tion. But adding omega-3 fatty acids to your meals can help min­i­mize the damage.”

While ear­lier research has revealed how fruc­tose harms the body through its role in dia­betes, obe­sity and fatty liver, this study is the first to uncover how the sweet­ener influ­ences the brain.

The UCLA team zeroed in on high-fructose corn syrup, an inex­pen­sive liq­uid six times sweeter than cane sugar, that is com­monly added to processed foods, includ­ing soft drinks, condi­ments, apple­sauce and baby food. The aver­age American con­sumes more than 40 pounds of high-fructose corn syrup per year, accord­ing to the U.S. Department of Agriculture.

“We’re not talk­ing about nat­u­rally occur­ring fruc­tose in fruits, which also con­tain impor­tant antiox­i­dants,” explained Gomez-Pinilla, who is also a mem­ber of UCLA’s Brain Research Institute and Brain Injury Research Center. “We’re con­cerned about high-fructose corn syrup that is added to man­u­fac­tured food prod­ucts as a sweet­ener and preservative.”

Gomez-Pinilla and study co-author Rahul Agrawal, a UCLA vis­it­ing post­doc­toral fel­low from India, 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 chem­i­cal con­nec­tions between brain cells that enable mem­ory and learning.

“DHA is essen­tial for synap­tic function—brain cells’ abil­ity to trans­mit sig­nals to one another,” Gomez-Pinilla said. “This is the mech­a­nism that makes learn­ing and mem­ory pos­si­ble. Our bod­ies can’t pro­duce enough DHA, so it must be sup­ple­mented through our diet.”

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. What they saw sur­prised them.

“The sec­ond group of rats nav­i­gated the maze much faster than the rats that did not receive omega-3 fatty acids,” Gomez-Pinilla said. “The DHA-deprived ani­mals were slower, and their brains showed a decline in synap­tic activ­ity. Their brain cells had trou­ble sig­nal­ing each other, dis­rupt­ing the rats’ abil­ity to think clearly and recall the route they’d learned six weeks earlier.”

The DHA-deprived rats also 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.

“Because insulin can pen­e­trate the blood–brain bar­rier, the hor­mone may sig­nal neu­rons to trig­ger reac­tions that dis­rupt learn­ing and cause mem­ory loss,” Gomez-Pinilla said.

He sus­pects that fruc­tose is the cul­prit behind the DHA-deficient rats’ brain dys­func­tion. 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.

“Insulin is impor­tant in the body for con­trol­ling blood sugar, but it may play a dif­fer­ent role in the brain, where insulin appears to dis­turb mem­ory and learn­ing,” he said. “Our study shows that a high-fructose diet harms the brain as well as the body. This is some­thing new.”

Gomez-Pinilla, a native of Chile and an exer­cise enthu­si­ast who prac­tices what he preaches, advises peo­ple to keep fruc­tose intake to a min­i­mum and swap sug­ary desserts for fresh berries and Greek yogurt, which he keeps within arm’s reach in a small refrig­er­a­tor in his office. An occa­sional bar of dark choco­late that hasn’t been processed with a lot of extra sweet­ener is fine too, he said.

Still plan­ning to throw cau­tion to the wind and indulge in a hot-fudge sun­dae? Then also eat foods rich in omega-3 fatty acids, like salmon, wal­nuts and flaxseeds, or take a daily DHA cap­sule. Gomez-Pinilla rec­om­mends one gram of DHA per day.

“Our find­ings sug­gest that con­sum­ing DHA reg­u­larly pro­tects the brain against fructose’s harm­ful effects,” said Gomez-Pinilla. “It’s like sav­ing money in the bank. You want to build a reserve for your brain to tap when it requires extra fuel to fight off future diseases.”

Source: University of California – Los Angeles Health Sciences Release