Sugar as Brain Food



This isn’t great news for dieters, but sometimes sugar can be a good thing. Roy Baumeister, a psychologist at Florida State University, had subjects perform a mentally taxing task – watching a video while being careful to ignore random words scrolling across the bottom of the screen. (Apparently, it takes quite a bit of concentration to NOT look at the scrolling words.) Then, the subjects were given a drink of lemonade and asked to perform another cognitively demanding task, choose an apartment based on descriptions of various options.

The catch was that some subjects drank lemonade made with real sugar, and others had lemonade made with Splenda, a sugar substitute without nutritional value. The performance differences on the apartment task were surprising.

Baumeister reported that the students who received the sugar-free lemonade were significantly more likely to choose impulsively and make poor decisions on the apartment task. He attributed this to the exhaustion of the prefrontal cortex in all subjects. The subjects who got the sugar were able to better restore function to that area of the brain. (Fifteen minutes was allowed to elapse after consuming the lemonade to permit the sugar to reach the brain.)

According to Jonah Lehrer, who reports on this work in How We Decide,

This research can also help explain why we get cranky when we’re hungry and tired: the brain is less able to suppress the negative emotions sparked by small annoyances. A bad mood is really just a run-down prefrontal cortex.

As a sugar-avoider, I find this research interesting. Maybe in addition to the caffeine in my black coffee and Coke Zero, a little shot of sugar now and them might keep my brain sharper. Add this finding to the work I described in Diet Drinks Don’t Fool the Brain, and it’s enough to make one go back to The Real Thing.

(Shutterstock image)

  1. Dennis Van Staalduinen says

    Wow, I’m going to go load up on pere Halloween Candy. Thanks NeuroMarketing!

  2. Darius says

    Eating sugar isn’t the only way to get enough glucose to the brain. You could eat a fruit, a natural juice… perhaps a cake. Or you could eat large amounts of pasta.

  3. Alecco says

    Sugar is good only for 20 minutes because it triggers insulin response. After that the glucose levels in blood crash usually below normal.

  4. Patricio says

    You have to be careful when you present partial findings such as this one, they can be very misleading. As Alecco said, sugar is only good for 20 minutes among other bad things that come from eating sugar. The pre-frontal cortex gets its energy from Oxygen. A much better source of oxygen is water. Staying hydrated is one of the best things you can do for your overall energy levels. As for caffeine, the “sharpness” you perceive by the rush of the caffeine has little to do with an increase in your mental ability. Caffeine activates the adrenal glands which release cortisol into the bloodstream. That triggers a flight response in the brain. This draws the energy from the pre-frontal cortex to activate the areas in the brain that are responsible for your flight response. Yes, caffeine picks you up, but it doesn’t help you in better decision making.

  5. Karen, Graphics Designer says

    I was actually avoiding sugars because my Dad is diabetic and I’m afraid of being one as well. Maybe I was taking it too seriously. I never though sugar could be a brain food. I need to share this post…thanks.

    1. Roger Dooley says

      I wouldn’t get carried away, Karen. The fact that sugar provides a short-lived cognitive boost for a tired brain doesn’t make it good for you!


  6. stephanie says

    This study is flawed. The group that did more poorly could have done so not because they didn’t get sugar, but because they were negatively effected by having Splenda.

  7. Teri says

    I found this blog because I googled sugar and brain – I noticed that on a very sugary day recently, my memory was sharper, my mood was better and overall I felt much, much better. My ‘day of donuts’ will not be repeated, but I will think twice about low-carbing and get on the bike instead.

  8. M.D. says

    I believe this post should be modified to ensure people are not getting the wrong message. Yes, your brain runs on sugar, but there is no need to “overload” on sugar to make your brain work. When the body prioritizes where glucose goes, the brain is always first priority. It is only in instances of starvation when our bodies use ketones (from fat) as an energy source instead. And lastly, research has shown people with diabetes (which means the glucose can’t go into cells), cognitive function declines. I would NOT emphasize eating sugar, especially when the glycemic index (spikes in blood glucose depending on the level of sugar in food) suggests people’s energy spike for a very quick moment of time and crash right after.

  9. Colby Lemon says

    The conclusion of this article should be that diet drinks might as well be water, in that they have essentially no nutritional value. Readers shouldn’t take away the message that sugar “feeds your brain”. They should take away the message that glucose feeds your brain. Sugar has glucose, but so does almost any food. And sugar has a lot of fructose, which is of zero use to your brain or any other organ. Dieters certainly should not be told that sugar (i.e. sucrose, or HFCS) are sometimes good for you, they should be told that eating (some) food is necessary to fuel your brain.

  10. Alicia says

    Do I need to eat more sugar to be smarter?

    No that’s not the message.How about getting diabet?

    I thing you should eat as much as you need,don’t have to overestimate the power of sugar for the brain.

  11. David H says

    “There are other reasons not to use sugar to boost cognition. The effective dose range is rather narrow, with too much glucose impairing, rather than enhancing, cognitive functions. How much is best? That varies with people’s metabolism and with the amount of glucose in their brains when they ingest it.” – Read more here

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