Is Processed Fructose Stealing Your Smarts?

By Michael A. Smith, MD

A new study from UCLA (University of California, Los Angeles) shows that what you eat can influence how you think.

Specifically, the researchers were worried about all of the fructose in the American diet. They reported that eating a diet heavy in processed fructose over the long term alters your brain’s ability to learn and remember information.

Let’s start by looking at fructose itself. What is it, and is it ever okay to eat it?

Fructose is a Natural Fruit Sugar

Fructose in its natural form is called fruit sugar. It’s a simple sugar found in many plants and is one of the three dietary monosaccharides, along with glucose and galactose. These simple sugars are absorbed directly into the bloodstream during digestion and can be used for immediate cellular energy.

From plant sources, fructose is found naturally in honey, tree and vine fruits, flowers, berries and most root vegetables. In plants, fructose may be present naturally as the monosaccharide or as a component of sucrose.

Here’s the point we’re trying to make: Fructose in its natural form is not the problem. In nature, sugars can be found in foods that are also rich in antioxidants and fiber. And those accompanying nutrients can help minimize the impact of natural sugar.

The UCLA researchers agree with us. They said, “We're less concerned about naturally occurring fructose in fruits, which also contain important antioxidants. We're more concerned about the fructose in high-fructose corn syrup, which is added to manufactured food products as a sweetener and preservative."1

So, yes, natural sources of fructose are okay. It’s the all of the fructose found in processed foods and syrups that is causing the problem. The stuff is literally everywhere.

Processed Fructose Lowers Brain Power

UCLA researchers studied two groups of rats that each consumed a fructose solution as drinking water for six weeks. Some of the rats were also given flaxseed oil concentrated with the omega-3 fat, DHA (docosahexaenoic acid). The researchers wanted to measure the impact of high dietary fructose (like what we get in syrups and processed foods) on brain function and whether or not DHA could counter any negative effects.1

Why DHA? Because research is showing that this omega-3 fat in particular is essential for healthy brain and nerve cell connections. And the more brain cell connections you have, the better your memory and problem solving prowess will be.

The rats were tested using a standard maze with visual landmarks before administering the fructose solution or fructose/DHA solution. Six weeks later, after administering the solutions, they were tested again using the same maze. Here’s what the researchers found:1

  • The fructose-only rats were slower and their brains showed a decline in synaptic activity (that’s the level of activation between brain cells). Their brain cells had more trouble signaling each other, disrupting the rats’ ability to think clearly and recall the route they had learned six weeks earlier.
  • The fructose-only rats developed signs of insulin resistance, a hallmark of type 2 diabetes. The UCLA scientists suspect that high doses of fructose can block insulin’s ability to regulate how cells use and store sugar for energy.
  • The fructose/DHA rats completed the maze significantly faster than the rats given fructose only.
This study, funded by the National Institute of Neurological Disorders and Stroke, concluded that high intake of fructose from processed sources may increase the risk of memory loss and cognitive decline.

Now, let’s be fair and balanced here. This was a rat study that looked at fructose from no particular source. But we do agree with the researchers’ statement that natural fructose found in fruits is better for you because it comes with antioxidants and fiber. Fructose found in sugary drinks and almost all processed foods is devoid of those additional nutrients and probably has an overall negative effect on your health.

So, what do you think about fructose, specifically processed fructose? Do you agree with the National Corn Growers Association that it’s perfectly safe and no different from table sugar?


  1. J Physiol. 2012 May 15;590(Pt 10):2485-99. Epub 2012 Apr 2.


Anonymous said...

I agree all the way! Common sense. Look back when I used to drink soda all the time and my memory was so much cloudy. And now that elimated sugary drinks my memory function has improved dramatically. Haha. ;)

Andy Haros

Andy25 said...

Also I know a youngster who drinks soft drinks every day and he's overweight and has man boobs at the age of 17 and is rather hyper too.

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