Though we may not have fully come to terms with it, in theory we know that high-fructose corn syrup (HFCS) is an adversary of health. Lots of work has been done looking at the effect of fructose on weight, liver function, diabetes risk, and even the growth of cancer cells. But not much has looked at the role of fructose in brain function, until now.
Researchers have just reported that among the list of bodily ills that fructose contributes to, it may also “make you dumb.” Luckily, eating a diet rich in the healthy omega-3 fatty acids seems to counteract this phenomenon.
In the new study, UCLA researchers had mice spend a few days learning to navigate a maze. Then some of the mice ate diets rich in omega-3 fatty acids or deficient in them; some mice also drank a fructose solution in the place of their regular drinking water. After six weeks on their respective diets, the team put the mice back in the maze to see how well they recalled it.
The mice who had eaten omega-3-deficient diets were slower at completing the maze than the ones who ate diets rich in omega-3s. Those who drank the fructose solution instead of water were the worst-off of all when it came to their cognitive capabilities.
The mice also had important differences in how their bodies – and brains – were metabolizing sugar and functioning overall. The mice who had eaten diets without omega-3s had higher triglyceride levels as well as higher glucose and insulin levels. In fact the mice seemed to enter a state of insulin resistance (a precursor to diabetes), but this too was reversed by the addition of omega-3s.
Perhaps most interesting was the fact that the brains of mice without omega-3s showed a decrease in synaptic activity, the means by which brain cells “talk” to one another and which is critical in learning and memory. “The DHA-deprived animals were slower,” said study author Fernando Gomez-Pinilla, “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.”
Insulin influences not only blood sugar, but it also affects the ways in which brain cells function. So being in a state of insulin-resistance might be what’s behind the problems in brain function. Gomez-Pinilla suggests that fructose might somehow block insulin’s effect on brain cells, and specifically how it signals neurons to store and release the sugar that is needed for the brain to function efficiently – and for us to think crisply and clearly.
The study also points to the fact that metabolic syndrome, which is plaguing so many Americans these days, can also adversely affect our cognitive abilities.
The important thing to remember is that not all fructose is created equal. “We’re not talking about naturally occurring fructose in fruits, which also contain important antioxidants,” explained Gomez-Pinilla. “We’re more concerned about the fructose in high-fructose corn syrup, which is added to manufactured food products as a sweetener and preservative.”
Luckily, omega-3s seem to counteract the effect of fructose in part, although it’s probably a good idea to cut down on highly processed, high-fructose foods in the first place. And since our bodies are not very good producers of DHA and EPA, taking in the healthy fatty acids through diet or supplements may also be wise. The best sources of DHA/EPA are cold-water fish like tuna and salmon, and for the vegetarians out there, these forms may also be found in seaweed and algae (in small amounts), or in concentrated seaweed/algae supplements. Gomez recommends consuming about one gram of DHA every day.
The bottom line is that omega-3s may protect our brains – not just now, but in the years to come. “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.”