Not so sweet news: Your candy cravings could be stifling your brain power

'Sugar coma' affecting cognitive function could be a real thing says science

'Sugar coma' affecting cognitive function could be a real thing says science

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As you digest another year and muddle through some post-holiday malaise while easing back into regular life, you may also be digesting an assortment of leftover holiday sweets. Tempting tupperwares of shortbread cookies and peppermint bark seem to punctuate every home and work surface this time of year. What's one more indulgence, right? Aside from torpedoing your resolution to eat better this year, all of that sugar could be making you a little, um, derpy.

If you've a mind to stay sharpish this year, new research out of the University of Otago in New Zealand suggests that you drop that snickerdoodle — the sugar blast it promises likely isn't doing your brain any favours. Cognitive function was found to be measurably impaired by glucose and sucrose. More specifically, scientists were able to establish two marked correlations to higher blood glucose: a reduced attention span and a diminished mental response time.  

While measuring their blood sugar levels, scientists had 49 subjects consume various beverages high in glucose, sucrose (think a packet of white table sugar), fructose (think sugar from fruit), or an artificial sweetener (think sucralose). Once the sweet drinks were downed, researchers then administered three tests that measured cognitive performance. The first analyzed response time, the second rated arithmetic prowess, and the last was a Stroop test. Printing the word "red" in bright green font and then asking a sugar addled reader to tell you what colour the letters are is a common measure of the Stroop effect. It's a processing delay that occurs when a human brain is presented with potentially conflicting information. It isn't easy to say green when you're reading red even if you're firing sugar-free on all cylinders — the interference of the opposing data is a real noodle-buster. At least for my noodle.   

Still, when it came to brain function, the tests found little favour with glucose and sucrose consumption. Not so with artificial sweeteners or fructose. Consider here that 100% of the carbs we eat are turned into glucose or fructose in the body. But fructose, unlike glucose, won't cross the blood-brain barrier to affect cognition. And the tests results were clear: subjects who'd guzzled down glucose or sucrose-heavy bevies were typically out performed by those who's tossed back the fructose or sucralose concoctions. So reach for a crisp apple if you're feeling peckish come 3:30 and not a chewy white chocolate chip macadamia nut affair (well, do your best anyway).

Dr Mei Peng, lead author of the study, says that the much joked about tendency to go semi-comatose after a high-carb feed is very much measurable, at least as far a mental dexterity is concerned. She told media her research "suggests that the 'sugar coma' — with regards to glucose — is indeed a real phenomenon, where levels of attention seem to decline after consumption of glucose-containing sugar." The fated carb crash.

A professor in the Department of Food Science at Otago, Peng admits she's "fascinated by how our senses influence our behaviour and affect our everyday lives." Most crucial for her is "how sugar consumption might change the way our brains work." How on you are in that afternoon meeting could be a direct function of how many chocolate covered peanut clusters you've just choked down. May that bolster your new year's resolution if it's a dietary endeavour.

Conflictingly, prior research has shown that sugar could bolster memory, at least in the short term. Like most nutritional science, it's new and complex. The brain loves fuel, particularly sugar, which previous research has found to be beneficial to keeping it puttering along. The brain also happens to be a really needy organ — the neediest of the lot, in fact — its fuel cut alone is an amazing 20% of the everything you eat. It needs sugar fuel. But this new study could point to kind of cognitive clogging when too much of the wrong kind of sugar is ingested.

Peng is adamant that her study is a preliminary one and more research is needed to solidify our understanding of sugar on the brain.  

Still, Peng's research isn't the first to point to sugar as something that stymies our noggins. A daily dowsing of the teen brain in sugary soda pop was shown to drown memory. Sugar, at least in teenage rats, caused inflammation in their hippocampus (or memory centre) and negatively affected their maze-solving skills. While a rat study does not a human correlation make, sugar is already a well-known inflammatory in humans. So, you know, sugar-free food for thought.  

Putting down the crueler will prove to be an uphill battle. We're hardwired to love the sugary stuff as soon as it hits our taste buds. If the evidence provided by an indulgent and satiating eyeroll isn't enough, consider that evolutionary science provides some data. "In the case of sweetness perception, we have evolved to favour this taste," says Peng. Sweetness is often linked to a higher caloric intake — great for survival when food is scarce but less ideal when all you've been hunting is Boston cream doughnuts.    

So go easy on the leftover sweets if you can swing it. It'll at least increase your chances of getting the new date right and save you from scratching out 2017 on your first few cheques this year.


Marc Beaulieu is a Montreal writer, producer, performer, professional host and mental health advocate whose one true love is weird news.