Cramming for a work project or school exam?
Beware … it appears that sweet foods and drinks can give Jack (or Jill) a duller brain.
If the results of a rat study apply to people – which seems likely – you'd be smart to go easy on sweet things and use omega-3s to shield your brain against the ones you can't resist.
The long-chain omega-3 fatty acids found in human cells and fish (DHA and EPA) are essential to our survival and to optimal health.
And it's increasingly clear that these omega-3s can also help reduce the damage caused by the standard American diet.
For several years, a California-based team's been examining the effects of junky, American-style diets on rats' brains.
The group's mission and main thesis are expressed on their UCLA NeuroLife Lab website:
“Our approach is to harness the power of diet and exercise to prevent or cure neurological and psychiatric disorders … the proper management of lifestyle habits can arm us with the brainpower necessary to fortify cognitive reserve and battle various brain and spinal cord diseases.”
Their prior findings in rats suggest that the standard American diet reduces the brain's “plasticity” … the cluster of characteristics that support our capacity for learning, memory, and recovery.
Loss of plasticity dulls the brain while making it more vulnerable to lifestyle-induced damage and less able to recover from injuries of physical or metabolic origin.
These investigations have been led by Fernando Gomez-Pinilla, Ph.D., professor of neurosurgery, integrative biology, and physiology at UCLA.
As Gomez-Pinilla's UCLA team wrote four years ago, “… [fast food] diet[s] impose a risk factor to the molecular machinery in charge of maintaining neuronal [brain] function ...” (Wu A et al. 2008).
The UCLA scientists hypothesize that exercise and diets high in omega-3s and food-borne antioxidants can also help people maintain brain plasticity.
Now, they've published another encouraging rat study … one with implications for the opposite roles of dietary sugars and omega-3s in people.
UCLA study tests omega-3 DHA against sugary brain damage
The new rat study from UCLA is the first to show how a diet high in fructose slows the brain, hampering memory and learning … and that omega-3 DHA can counteract the disruption (Agrawal R, Gomez-Pinilla F 2012).
The findings, albeit from research in animals, should be of interest to people, since they suggest that indulging in soda and sweets routinely for as little as six weeks may blunt your brain.
“Our findings illustrate that what you eat affects how you think,” said Gomez-Pinilla. “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” (UCLA 2012).
“[Omega-3] 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” (UCLA 2012).
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 focused on high-fructose corn syrup (HFCS), which is ubiquitous in processed foods, soft drinks, condiments, sauces, dressings, and even baby food ... which explains why the average American consumes more than 40 pounds of HFCS annually.
are full of fructose
It's important to stress that cane sugar (white or brown) and high-fructose corn syrup (HFCS) consist of equal parts fructose and glucose … with little or no evidence than cane sugar is any healthier than HFCS.
However, focusing too much on high-fructose corn syrup (HFCS) can be a deceptive distraction from the evils of excessive intake of any and all sources of fructose.
Heart and metabolic risks are tied to excess intake of any and all caloric sweeteners … from honey and agave or maple syrups to cane sugar and high-fructose corn syrup (HFCS): see “Sugar Takes Another Heart-Health Hit.”
Note: Compared with HFCS, cane sugar and other natural sweeteners contain just as much fructose … see our sidebar, “All sweeteners are full of fructose”, which covers some of the unique adverse effects of HFCS.
Omega-3 DHA blunted sugar-induced brain damage
All of the animals were fed standard rat chow and trained on a maze twice daily for five days.
Then the authors divided the rats into two groups – Control and Omega-3.
For six weeks, both groups got fructose in their drinking water but were fed a different diet:
*The supplemented chow contained 0.5% flaxseed oil and 1.2% DHA. Flaxseed oil contains the short-chain omega-3 called ALA, very little of which gets converted to DHA, so it's not clear why the researchers included it.
The UCLA team tested how well the rats were able to navigate a maze that contained numerous holes and visual landmarks but only one exit.
Six weeks later, the researchers tested the rats' ability to recall the route and escape the maze.
What they saw supported the hypothesis that omega-3 DHA may help reduce the brain-dulling effects of sugar.
“The second [omega-3-supplemented] group of rats navigated the maze much faster than the rats that did not receive omega-3 fatty acids,” Gomez-Pinilla said. (UCLA 2012)
He added, “The [omega-3] 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” (UCLA 2012).
Fructose also raised rat's insulin resistance
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. (UCLA 2012)
He suspects that this special effect of fructose was a key culprit behind the DHA-deficient rats' brain dysfunctions and consequent problems remembering the maze pattern.
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” (UCLA 2012).
UCLA researchers offer brainy diet advice
Gomez-Pinilla advises people to keep fructose intake to a minimum and swap sugary desserts for fresh berries and Greek yogurt, which he keeps in a small refrigerator in his office.
An occasional bar of dark chocolate that hasn't been made without a lot of sugar is fine too, he said.
(Look for bars containing at least 70% cocoa solids … the more the better, to reduce the proportion of sugar and maximize the amount of antioxidant-rich cocoa.)
To make it safer to enjoy sweets in moderation, Gomez-Pinilla urges people to routinely eat foods rich in omega-3 DHA, like salmon, or take a daily omega-3 fish oil capsule … he recommends getting enough fish oil to provide 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 ...” (UCLA 2012)
The UCLA study was funded by the National Institute of Neurological Disorders and Stroke. Gomez-Pinilla's lab will next examine the role of diet in recovery from brain trauma.
Agrawal R, Gomez-Pinilla F. 'Metabolic syndrome' in the brain: deficiency in omega-3 fatty acid exacerbates dysfunctions in insulin receptor signalling and cognition. J Physiol. 2012 May 15;590(Pt 10):2485-99. Epub 2012 Apr 2. Accessed at http://jp.physoc.org/content/early/2012/03/31/jphysiol.2012.230078.abstract
Heinrichs SC. Dietary omega-3 fatty acid supplementation for optimizing neuronal structure and function. Mol Nutr Food Res. 2010 Apr;54(4):447-56. Review.
Rayssiguier Y, Gueux E, Nowacki W, Rock E, Mazur A. High fructose consumption combined with low dietary magnesium intake may increase the incidence of the metabolic syndrome by inducing inflammation. Magnes Res. 2006 Dec;19(4):237-43. Review.
University of California Los Angeles (UCLA). Sugar makes you stupid: UCLA study shows high-fructose diet sabotages learning, memory. May 15, 2012. Accessed at http://www.eurekalert.org/pub_releases/2012-05/uoc--smy051512.php
Wu A, Ying Z, Gomez-Pinilla F. Docosahexaenoic acid dietary supplementation enhances the effects of exercise on synaptic plasticity and cognition. Neuroscience. 2008 Aug 26;155(3):751-9. Epub 2008 Jun 17.
Wu A, Ying Z, Gomez-Pinilla F. Dietary omega-3 fatty acids normalize BDNF levels, reduce oxidative damage, and counteract learning disability after traumatic brain injury in rats. J Neurotrauma. 2004 Oct;21(10):1457-67.
Wu A, Ying Z, Gomez-Pinilla F. The salutary effects of DHA dietary supplementation on cognition, neuroplasticity, and membrane homeostasis after brain trauma. J Neurotrauma. 2011 Oct;28(10):2113-22. Epub 2011 Oct 4.